1
|
Study of High-Transverse-Momentum Higgs Boson Production in Association with a Vector Boson in the qqbb Final State with the ATLAS Detector. PHYSICAL REVIEW LETTERS 2024; 132:131802. [PMID: 38613283 DOI: 10.1103/physrevlett.132.131802] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2023] [Accepted: 02/26/2024] [Indexed: 04/14/2024]
Abstract
This Letter presents the first study of Higgs boson production in association with a vector boson (V=W or Z) in the fully hadronic qqbb final state using data recorded by the ATLAS detector at the LHC in proton-proton collisions at sqrt[s]=13 TeV and corresponding to an integrated luminosity of 137 fb^{-1}. The vector bosons and Higgs bosons are each reconstructed as large-radius jets and tagged using jet substructure techniques. Dedicated tagging algorithms exploiting b-tagging properties are used to identify jets consistent with Higgs bosons decaying into bb[over ¯]. Dominant backgrounds from multijet production are determined directly from the data, and a likelihood fit to the jet mass distribution of Higgs boson candidates is used to extract the number of signal events. The VH production cross section is measured inclusively and differentially in several ranges of Higgs boson transverse momentum: 250-450, 450-650, and greater than 650 GeV. The inclusive signal yield relative to the standard model expectation is observed to be μ=1.4_{-0.9}^{+1.0} and the corresponding cross section is 3.1±1.3(stat)_{-1.4}^{+1.8}(syst) pb.
Collapse
|
2
|
Measurement of the Centrality Dependence of the Dijet Yield in p+Pb Collisions at sqrt[s_{NN}]=8.16 TeV with the ATLAS Detector. PHYSICAL REVIEW LETTERS 2024; 132:102301. [PMID: 38518341 DOI: 10.1103/physrevlett.132.102301] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/04/2023] [Revised: 11/07/2023] [Accepted: 12/04/2023] [Indexed: 03/24/2024]
Abstract
ATLAS measured the centrality dependence of the dijet yield using 165 nb^{-1} of p+Pb data collected at sqrt[s_{NN}]=8.16 TeV in 2016. The event centrality, which reflects the p+Pb impact parameter, is characterized by the total transverse energy registered in the Pb-going side of the forward calorimeter. The central-to-peripheral ratio of the scaled dijet yields, R_{CP}, is evaluated, and the results are presented as a function of variables that reflect the kinematics of the initial hard parton scattering process. The R_{CP} shows a scaling with the Bjorken x of the parton originating from the proton, x_{p}, while no such trend is observed as a function of x_{Pb}. This analysis provides unique input to understanding the role of small proton spatial configurations in p+Pb collisions by covering parton momentum fractions from the valence region down to x_{p}∼10^{-3} and x_{Pb}∼4×10^{-4}.
Collapse
|
3
|
Search for New Phenomena in Two-Body Invariant Mass Distributions Using Unsupervised Machine Learning for Anomaly Detection at sqrt[s]=13 TeV with the ATLAS Detector. PHYSICAL REVIEW LETTERS 2024; 132:081801. [PMID: 38457710 DOI: 10.1103/physrevlett.132.081801] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/10/2023] [Accepted: 12/13/2023] [Indexed: 03/10/2024]
Abstract
Searches for new resonances are performed using an unsupervised anomaly-detection technique. Events with at least one electron or muon are selected from 140 fb^{-1} of pp collisions at sqrt[s]=13 TeV recorded by ATLAS at the Large Hadron Collider. The approach involves training an autoencoder on data, and subsequently defining anomalous regions based on the reconstruction loss of the decoder. Studies focus on nine invariant mass spectra that contain pairs of objects consisting of one light jet or b jet and either one lepton (e,μ), photon, or second light jet or b jet in the anomalous regions. No significant deviations from the background hypotheses are observed. Limits on contributions from generic Gaussian signals with various widths of the resonance mass are obtained for nine invariant masses in the anomalous regions.
Collapse
|
4
|
Observation of WZγ Production in pp Collisions at sqrt[s]=13 TeV with the ATLAS Detector. PHYSICAL REVIEW LETTERS 2024; 132:021802. [PMID: 38277610 DOI: 10.1103/physrevlett.132.021802] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/29/2023] [Revised: 09/30/2023] [Accepted: 11/08/2023] [Indexed: 01/28/2024]
Abstract
This Letter reports the observation of WZγ production and a measurement of its cross section using 140.1±1.2 fb^{-1} of proton-proton collision data recorded at a center-of-mass energy of 13 TeV by the ATLAS detector at the Large Hadron Collider. The WZγ production cross section, with both the W and Z bosons decaying leptonically, pp→WZγ→ℓ^{'}^{±}νℓ^{+}ℓ^{-}γ (ℓ^{(^{'})}=e, μ), is measured in a fiducial phase-space region defined such that the leptons and the photon have high transverse momentum and the photon is isolated. The cross section is found to be 2.01±0.30(stat)±0.16(syst) fb. The corresponding standard model predicted cross section calculated at next-to-leading order in perturbative quantum chromodynamics and at leading order in the electroweak coupling constant is 1.50±0.06 fb. The observed significance of the WZγ signal is 6.3σ, compared with an expected significance of 5.0σ.
Collapse
|
5
|
Identifying opportunities for prevention of adverse outcomes following female genital fistula repair: protocol for a mixed-methods study in Uganda. Reprod Health 2024; 21:2. [PMID: 38178156 PMCID: PMC10768188 DOI: 10.1186/s12978-023-01732-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2023] [Accepted: 12/28/2023] [Indexed: 01/06/2024] Open
Abstract
BACKGROUND Female genital fistula is a traumatic debilitating injury, frequently caused by prolonged obstructed labor, affecting between 500,000-2 million women in lower-resource settings. Vesicovaginal fistula causes urinary incontinence, and other morbidity may occur during fistula development. Women with fistula are stigmatized, limit social and economic engagement, and experience psychiatric morbidity. Improved surgical access has reduced fistula consequences yet post-repair risks impacting quality of life and well-being include fistula repair breakdown or recurrence and ongoing or changing urine leakage or incontinence. Limited evidence on risk factors contributing to adverse outcomes hinders interventions to mitigate adverse events. This study aims to quantify these adverse risks and inform clinical and counseling interventions to optimize women's health and quality of life following fistula repair through: identifying predictors and characteristics of post-repair fistula breakdown and recurrence (Objective 1) and post-repair incontinence (Objective 2), and to identify feasible and acceptable intervention strategies (Objective 3). METHODS This mixed-methods study incorporates a prospective cohort of women with successful vesicovaginal fistula repair at approximately 12 fistula repair centers in Uganda (Objectives 1-2) followed by qualitative inquiry among key stakeholders (Objective 3). Cohort participants will have a baseline visit at the time of surgery followed by data collection at 2 weeks, 6 weeks, 3 months and quarterly thereafter for 3 years. Primary predictors to be evaluated include patient-related factors, fistula-related factors, fistula repair-related factors, and post-repair behaviors and exposures, collected via structured questionnaire at all data collection points. Clinical exams will be conducted at baseline, 2 weeks post-surgery, and for outcome confirmation at symptom development. Primary outcomes are fistula repair breakdown or fistula recurrence and post-repair incontinence. In-depth interviews will be conducted with cohort participants (n ~ 40) and other key stakeholders (~ 40 including family, peers, community members and clinical/social service providers) to inform feasibility and acceptability of recommendations. DISCUSSION Participant recruitment is underway. This study is expected to identify key predictors that can directly improve fistula repair and post-repair programs and women's outcomes, optimizing health and quality of life. Furthermore, our study will create a comprehensive longitudinal dataset capable of supporting broad inquiry into post-fistula repair health. Trial Registration ClinicalTrials.gov Identifier: NCT05437939.
Collapse
|
6
|
Combined Measurement of the Higgs Boson Mass from the H→γγ and H→ZZ^{*}→4ℓ Decay Channels with the ATLAS Detector Using sqrt[s]=7, 8, and 13 TeV pp Collision Data. PHYSICAL REVIEW LETTERS 2023; 131:251802. [PMID: 38181336 DOI: 10.1103/physrevlett.131.251802] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2023] [Accepted: 11/06/2023] [Indexed: 01/07/2024]
Abstract
A measurement of the mass of the Higgs boson combining the H→ZZ^{*}→4ℓ and H→γγ decay channels is presented. The result is based on 140 fb^{-1} of proton-proton collision data collected by the ATLAS detector during LHC run 2 at a center-of-mass energy of 13 TeV combined with the run 1 ATLAS mass measurement, performed at center-of-mass energies of 7 and 8 TeV, yielding a Higgs boson mass of 125.11±0.09(stat)±0.06(syst)=125.11±0.11 GeV. This corresponds to a 0.09% precision achieved on this fundamental parameter of the Standard Model of particle physics.
Collapse
|
7
|
Search for Dark Photons in Rare Z Boson Decays with the ATLAS Detector. PHYSICAL REVIEW LETTERS 2023; 131:251801. [PMID: 38181367 DOI: 10.1103/physrevlett.131.251801] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2023] [Accepted: 10/11/2023] [Indexed: 01/07/2024]
Abstract
A search for events with a dark photon produced in association with a dark Higgs boson via rare decays of the standard model Z boson is presented, using 139 fb^{-1} of sqrt[s]=13 TeV proton-proton collision data recorded by the ATLAS detector at the Large Hadron Collider. The dark boson decays into a pair of dark photons, and at least two of the three dark photons must each decay into a pair of electrons or muons, resulting in at least two same-flavor opposite-charge lepton pairs in the final state. The data are found to be consistent with the background prediction, and upper limits are set on the dark photon's coupling to the dark Higgs boson times the kinetic mixing between the standard model photon and the dark photon, α_{D}ϵ^{2}, in the dark photon mass range of [5, 40] GeV except for the ϒ mass window [8.8, 11.1] GeV. This search explores new parameter space not previously excluded by other experiments.
Collapse
|
8
|
Observation of Single-Top-Quark Production in Association with a Photon Using the ATLAS Detector. PHYSICAL REVIEW LETTERS 2023; 131:181901. [PMID: 37977601 DOI: 10.1103/physrevlett.131.181901] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2023] [Revised: 08/03/2023] [Accepted: 08/09/2023] [Indexed: 11/19/2023]
Abstract
This Letter reports the observation of single top quarks produced together with a photon, which directly probes the electroweak coupling of the top quark. The analysis uses 139 fb^{-1} of 13 TeV proton-proton collision data collected with the ATLAS detector at the Large Hadron Collider. Requiring a photon with transverse momentum larger than 20 GeV and within the detector acceptance, the fiducial cross section is measured to be 688±23(stat) _{-71}^{+75}(syst) fb, to be compared with the standard model prediction of 515_{-42}^{+36} fb at next-to-leading order in QCD.
Collapse
|
9
|
Factors associated with reintegration trajectory following female genital fistula surgery in Uganda. AJOG GLOBAL REPORTS 2023; 3:100261. [PMID: 37719642 PMCID: PMC10502369 DOI: 10.1016/j.xagr.2023.100261] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/19/2023] Open
Abstract
BACKGROUND A female genital fistula, primarily caused by prolonged obstructed labor or after cesarean delivery in resource-limited countries, affects 500,000 to 2,000,000 women worldwide. Fistula is preventable with timely access to high-quality obstetrical care. Access to surgical repair of a female genital fistula has greatly increased over time. However, research surrounding postrepair reintegration, the process of returning to an individual's normal life, remains limited, and further efforts are needed to understand the factors shaping women's ability to rebuild their relationships and lives following repair. OBJECTIVE This study aimed to characterize the 12-month reintegration trajectory after female genital fistula repair by participant sociodemographic and clinical characteristics. STUDY DESIGN This study analyzed quantitative survey and medical record data of women (N=60) participating in a longitudinal cohort study assessing recovery after genital fistula repair in Uganda, with baseline and 4 quarterly follow-up assessments in 12 months. The primary outcome of reintegration was assessed using a 19-item postfistula repair reintegration instrument (range, 0-100) where a higher score represents better reintegration. Predictors of interest included parity and living children, quality of life, depressive symptoms at baseline, self-esteem, stigma, trauma, physical symptoms, and social support. We described participant baseline characteristics using means and proportions and estimated a series of mixed-effects linear regression models, including interactions of characteristics with time to understand how these characteristics influence reintegration trajectory in the 12 months after repair. RESULTS The participants' physical and psychosocial morbidities at baseline were high; more than 80% of participants reported fistula-related physical symptoms, 82% of participants described their general health as poor, and measures of self-esteem, overall social support, and overall quality of life were low. The mean reintegration score at baseline was 33 (standard deviation, 20), which increased to 78 (standard deviation, 19) at 12 months after fistula repair. The participant sociodemographic characteristics statistically associated with reintegration included any living children (β, 1.08; 95% confidence interval, -0.08 to 2.23). Moreover, psychosocial factors significantly affected reintegration with steeper trajectories for women with depressive symptoms (β, 0.89; 95% confidence interval, 0.02-1.75) or women experiencing internalized stigma (β, 0.05; 95% confidence interval, -0.00 to 0.11) and less steep for those with higher self-esteem (β, -0.11; 95% confidence interval, -0.24 to 0.01), overall social support (β, -0.06; 95% confidence interval, -0.12 to -0.01), and partner support (β, -0.21; 95% confidence interval, -0.35 to -0.07). CONCLUSION Understanding the prominent factors associated with differences in reintegration trajectories across the year after genital fistula surgery has the potential to inform interventions that mitigate challenges and improve women's postrepair recovery experiences.
Collapse
|
10
|
Author Correction: A detailed map of Higgs boson interactions by the ATLAS experiment ten years after the discovery. Nature 2023; 623:E5. [PMID: 37853131 PMCID: PMC10620074 DOI: 10.1038/s41586-023-06248-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2023]
|
11
|
Measurement of Suppression of Large-Radius Jets and Its Dependence on Substructure in Pb+Pb Collisions at sqrt[s_{NN}]=5.02 TeV with the ATLAS Detector. PHYSICAL REVIEW LETTERS 2023; 131:172301. [PMID: 37955510 DOI: 10.1103/physrevlett.131.172301] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/16/2023] [Revised: 05/11/2023] [Accepted: 09/18/2023] [Indexed: 11/14/2023]
Abstract
This letter presents a measurement of the nuclear modification factor of large-radius jets in sqrt[s_{NN}]=5.02 TeV Pb+Pb collisions by the ATLAS experiment. The measurement is performed using 1.72 nb^{-1} and 257 pb^{-1} of Pb+Pb and pp data, respectively. The large-radius jets are reconstructed with the anti-k_{t} algorithm using a radius parameter of R=1.0, by reclustering anti-k_{t} R=0.2 jets, and are measured over the transverse momentum (p_{T}) kinematic range of 158
Collapse
|
12
|
Measurement of the Sensitivity of Two-Particle Correlations in pp Collisions to the Presence of Hard Scatterings. PHYSICAL REVIEW LETTERS 2023; 131:162301. [PMID: 37925689 DOI: 10.1103/physrevlett.131.162301] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/03/2023] [Revised: 06/18/2023] [Accepted: 08/09/2023] [Indexed: 11/07/2023]
Abstract
A key open question in the study of multiparticle production in high-energy pp collisions is the relationship between the "ridge"-i.e., the observed azimuthal correlations between particles in the underlying event that extend over all rapidities-and hard or semihard scattering processes. In particular, it is not known whether jets or their soft fragments are correlated with particles in the underlying event. To address this question, two-particle correlations are measured in pp collisions at sqrt[s]=13 TeV using data collected by the ATLAS experiment at the LHC, with an integrated luminosity of 15.8 pb^{-1}, in two different configurations. In the first case, charged particles associated with jets are excluded from the correlation analysis, while in the second case, correlations are measured between particles within jets and charged particles from the underlying event. Second-order flow coefficients, v_{2}, are presented as a function of event multiplicity and transverse momentum. These measurements show that excluding particles associated with jets does not affect the measured correlations. Moreover, particles associated with jets do not exhibit any significant azimuthal correlations with the underlying event, ruling out hard processes contributing to the ridge.
Collapse
|
13
|
Observation of an Excess of Dicharmonium Events in the Four-Muon Final State with the ATLAS Detector. PHYSICAL REVIEW LETTERS 2023; 131:151902. [PMID: 37897770 DOI: 10.1103/physrevlett.131.151902] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/19/2023] [Revised: 05/31/2023] [Accepted: 08/11/2023] [Indexed: 10/30/2023]
Abstract
A search is made for potential ccc[over ¯]c[over ¯] tetraquarks decaying into a pair of charmonium states in the four muon final state using proton-proton collision data at sqrt[s]=13 TeV, corresponding to an integrated luminosity of 140 fb^{-1} recorded by the ATLAS experiment at LHC. Two decay channels, J/ψ+J/ψ→4μ and J/ψ+ψ(2S)→4μ, are studied. Backgrounds are estimated based on a hybrid approach involving Monte Carlo simulations and data-driven methods. Statistically significant excesses with respect to backgrounds dominated by the single parton scattering are seen in the di-J/ψ channel consistent with a narrow resonance at 6.9 GeV and a broader structure at lower mass. A statistically significant excess is also seen in the J/ψ+ψ(2S) channel. The fitted masses and decay widths of the structures are reported.
Collapse
|
14
|
Observation of the γγ→ττ Process in Pb+Pb Collisions and Constraints on the τ-Lepton Anomalous Magnetic Moment with the ATLAS Detector. PHYSICAL REVIEW LETTERS 2023; 131:151802. [PMID: 37897746 DOI: 10.1103/physrevlett.131.151802] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/03/2022] [Accepted: 07/07/2022] [Indexed: 10/30/2023]
Abstract
This Letter reports the observation of τ-lepton-pair production in ultraperipheral lead-lead collisions Pb+Pb→Pb(γγ→ττ)Pb and constraints on the τ-lepton anomalous magnetic moment a_{τ}. The dataset corresponds to an integrated luminosity of 1.44 nb^{-1} of LHC Pb+Pb collisions at sqrt[s_{NN}]=5.02 TeV recorded by the ATLAS experiment in 2018. Selected events contain one muon from a τ-lepton decay, an electron or charged-particle track(s) from the other τ-lepton decay, little additional central-detector activity, and no forward neutrons. The γγ→ττ process is observed in Pb+Pb collisions with a significance exceeding 5 standard deviations and a signal strength of μ_{ττ}=1.03_{-0.05}^{+0.06} assuming the standard model value for a_{τ}. To measure a_{τ}, a template fit to the muon transverse-momentum distribution from τ-lepton candidates is performed, using a dimuon (γγ→μμ) control sample to constrain systematic uncertainties. The observed 95% confidence-level interval for a_{τ} is -0.057
Collapse
|
15
|
Contraceptive preferences and adoption following female genital fistula surgery in Uganda: a mixed-methods study. Reprod Health 2023; 20:121. [PMID: 37598146 PMCID: PMC10439586 DOI: 10.1186/s12978-023-01663-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2023] [Accepted: 08/07/2023] [Indexed: 08/21/2023] Open
Abstract
BACKGROUND Female genital fistula, largely caused by prolonged obstructed labour, is treated by surgical repair. Preventing pregnancy for a minimum period post-repair is recommended to ensure adequate healing and optimize post-repair outcomes. METHODS We examined contraceptive preferences and use among Ugandan fistula patients (n = 60) in the year following genital fistula surgery using mixed-methods. Sexual activity, contraceptive use and pregnancy status were recorded quarterly for 12 months after surgery. In-depth interviews among purposively selected participants (n = 30) explored intimate relationships, sexual experiences, reproductive intentions, and contraceptive use. RESULTS Median participant age was 28 years and almost half (48%) were married or living with partners. Counselling was provided to 97% of participants on delaying sexual intercourse, but only 59% received counselling on contraception. Sexual activity was reported by 32% after 6 months and 50% after 12 months. Eighty-three percent reported not trying for pregnancy. Among sexually active participants, contraceptive use was low at baseline (36%) but increased to 73% at 12 months. Six (10%) women became pregnant including two within 3 months post-repair. Interview participants who desired children immediately were young, had fewer children, experienced stillbirth at fistula development, and felt pressure from partners. Women adopted contraception to fully recover from fistula surgery and avoid adverse outcomes. Others simply preferred to delay childbearing. Reasons cited for not adopting contraception included misconceptions related to their fertility and to contraceptive methods and insufficient or unclear healthcare provider advice on their preferred methods. CONCLUSIONS A high proportion of patients were not counselled by healthcare providers on contraception. Provision of comprehensive patient-centred contraceptive counselling at the time of fistula surgery and beyond is important for patients to optimize healing from fistula and minimize recurrence, as well as to meet their own reproductive preferences.
Collapse
|
16
|
Strong Constraints on Jet Quenching in Centrality-Dependent p+Pb Collisions at 5.02 TeV from ATLAS. PHYSICAL REVIEW LETTERS 2023; 131:072301. [PMID: 37656838 DOI: 10.1103/physrevlett.131.072301] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/03/2022] [Revised: 10/04/2022] [Accepted: 11/17/2022] [Indexed: 09/03/2023]
Abstract
Jet quenching is the process of color-charged partons losing energy via interactions with quark-gluon plasma droplets created in heavy-ion collisions. The collective expansion of such droplets is well described by viscous hydrodynamics. Similar evidence of collectivity is consistently observed in smaller collision systems, including pp and p+Pb collisions. In contrast, while jet quenching is observed in Pb+Pb collisions, no evidence has been found in these small systems to date, raising fundamental questions about the nature of the system created in these collisions. The ATLAS experiment at the Large Hadron Collider has measured the yield of charged hadrons correlated with reconstructed jets in 0.36 nb^{-1} of p+Pb and 3.6 pb^{-1} of pp collisions at 5.02 TeV. The yields of charged hadrons with p_{T}^{ch}>0.5 GeV near and opposite in azimuth to jets with p_{T}^{jet}>30 or 60 GeV, and the ratios of these yields between p+Pb and pp collisions, I_{pPb}, are reported. The collision centrality of p+Pb events is categorized by the energy deposited by forward neutrons from the struck nucleus. The I_{pPb} values are consistent with unity within a few percent for hadrons with p_{T}^{ch}>4 GeV at all centralities. These data provide new, strong constraints that preclude almost any parton energy loss in central p+Pb collisions.
Collapse
|
17
|
Search for Heavy Neutral Leptons in Decays of W Bosons Using a Dilepton Displaced Vertex in sqrt[s]=13 TeV pp Collisions with the ATLAS Detector. PHYSICAL REVIEW LETTERS 2023; 131:061803. [PMID: 37625051 DOI: 10.1103/physrevlett.131.061803] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2022] [Accepted: 08/08/2022] [Indexed: 08/27/2023]
Abstract
A search for a long-lived, heavy neutral lepton (N) in 139 fb^{-1} of sqrt[s]=13 TeV pp collision data collected by the ATLAS detector at the Large Hadron Collider is reported. The N is produced via W→Nμ or W→Ne and decays into two charged leptons and a neutrino, forming a displaced vertex. The N mass is used to discriminate between signal and background. No signal is observed, and limits are set on the squared mixing parameters of the N with the left-handed neutrino states for the N mass range 3 GeV
Collapse
|
18
|
Test of CP Invariance in Higgs Boson Vector-Boson-Fusion Production Using the H→γγ Channel with the ATLAS Detector. PHYSICAL REVIEW LETTERS 2023; 131:061802. [PMID: 37625052 DOI: 10.1103/physrevlett.131.061802] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/05/2022] [Accepted: 02/03/2023] [Indexed: 08/27/2023]
Abstract
A test of CP invariance in Higgs boson production via vector-boson fusion has been performed in the H→γγ channel using 139 fb^{-1} of proton-proton collision data at sqrt[s]=13 TeV collected by the ATLAS detector at the LHC. The optimal observable method is used to probe the CP structure of interactions between the Higgs boson and electroweak gauge bosons, as described by an effective field theory. No sign of CP violation is observed in the data. Constraints are set on the parameters describing the strength of the CP-odd component in the coupling between the Higgs boson and the electroweak gauge bosons in two effective field theory bases: d[over ˜] in the HISZ basis and c_{HW[over ˜]} in the Warsaw basis. The results presented are the most stringent constraints on CP violation in the coupling between Higgs and weak bosons. The 95% C.L. constraint on d[over ˜] is derived for the first time and the 95% C.L. constraint on c_{HW[over ˜]} has been improved by a factor of 5 compared to the previous measurement.
Collapse
|
19
|
Identifying Opportunities for Prevention of Adverse Outcomes Following Female Genital Fistula Repair: Protocol for a Mixed-Methods Study in Uganda. RESEARCH SQUARE 2023:rs.3.rs-2879899. [PMID: 37205399 PMCID: PMC10187434 DOI: 10.21203/rs.3.rs-2879899/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Background Female genital fistula is a traumatic debilitating injury, frequently caused by prolonged obstructed labor, affecting between 500,000-2 million women in lower-resource settings. Vesicovaginal fistula causes urinary incontinence. Other gynecologic, neurologic and orthopedic morbidity may occur during fistula development. Women with fistula are stigmatized; limit engagement in social, economic, or religious activities; and report high psychiatric morbidity. Improved global surgical access has reduced fistula consequences yet post-repair risks impacting quality of life and well-being include fistula repair breakdown or recurrence and ongoing or changing urine leakage or incontinence. Limited evidence on risk factors contributing to adverse outcomes hinders interventions to mitigate adverse events, protecting health and quality of life after surgery. This study seeks to identify predictors and characteristics of post-repair fistula breakdown and recurrence (Aim 1) and post-repair incontinence (Aim 2), and to identify feasible and acceptable intervention strategies (Aim 3). Methods This mixed-methods study incorporates a prospective cohort study of women with successful vesicovaginal fistula repair at approximately 12 fistula repair centers and affiliated care sites in Uganda (Aims 1-2) followed by qualitative inquiry among key stakeholders (Aim 3). Cohort participants will have a baseline visit at the time of surgery followed by data collection at 2 weeks, 6 weeks, 3 months and quarterly thereafter for 3 years. Primary predictors to be evaluated include patient-related factors, fistula-related factors, fistula repair-related factors, and post-repair behaviors and exposures, collected via structured questionnaire at all data collection points. Clinical exams will be conducted at baseline, 2 weeks post-surgery, and for outcome confirmation at symptom development. Primary outcomes are fistula repair breakdown or fistula recurrence and post-repair incontinence. In-depth interviews will be conducted with cohort participants (n ~ 40) and other key stakeholders (~ 40 including family, peers, community members and clinical/social service providers) to develop feasible and acceptable intervention concepts for adjustment of identified risk factors. Discussion Participant recruitment is underway. This study is expected to identify key predictors that can directly improve fistula repair and post-repair programs and women's outcomes, optimizing health and quality of life. Furthermore, our study will create a comprehensive longitudinal dataset capable of supporting broad inquiry into post-fistula repair health. Trial Registration ClinicalTrials.gov Identifier: NCT05437939.
Collapse
|
20
|
Characteristics and outcomes of patients with pelvic organ prolapse: an analysis of data from Mulago National Referral Hospital from 2007-2016. Afr Health Sci 2023; 23:410-416. [PMID: 37545968 PMCID: PMC10398439 DOI: 10.4314/ahs.v23i1.43] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/08/2023] Open
Abstract
INTRODUCTION Pelvic organ prolapse (POP) is associated with negative physical, social, psychological, and sexual experiences. There is paucity of data in low and middle income countries like Uganda. The purpose of this study was to describe clinical characteristics and outcomes of patients undergoing surgery for POP from 2007 to 2016. METHODS The study was conducted at Mulago National Referral Hospital from 2014 to 2016. We conducted a retrospective review of the urogynecology surgical records using a standardized medical record abstraction form. Data of 222 POP patients were abstracted and managed using REDCap. Analysis was performed using Stata statistical software, v14. RESULTS The mean participant age and parity was 57 years and 7 respectively. Ninety four percent of participants presented with a mass protruding from the vagina, 38% with uterine prolapse and 32% with cystocoele. Anaemia and hypertension were common comorbidities. Women underwent a variety of surgery types, and 35% experienced persistent pain post-operatively. At hospital discharge, 83% had achieved either complete resolution or improvement in their condition. CONCLUSIONS Measures encouraging presentation for care as soon as symptoms are experienced and reduction of total fertility rate will be beneficial. Patients with POP should be routinely screened for anaemia and hypertension.
Collapse
|
21
|
Feasibility and acceptability of mobile phone data collection for longitudinal follow-up among patients treated for obstetric fistula in Uganda. Health Care Women Int 2022; 43:1340-1354. [PMID: 33030977 PMCID: PMC9318213 DOI: 10.1080/07399332.2020.1825439] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2018] [Revised: 09/11/2020] [Accepted: 09/15/2020] [Indexed: 10/23/2022]
Abstract
Rapid dissemination of mobile technology provides substantial opportunity for overcoming challenges reaching rural and marginalized populations. We assessed feasibility and acceptability of longitudinal mobile data capture among women undergoing fistula surgery in Uganda (n = 60) in 2014-2015. Participants were followed for 12 months following surgery, with data captured quarterly, followed by interviews at 12 months. Participant retention was high (97%). Most respondents reported no difficulty with mobile data capture (range 93%-100%), and preferred mobile interview (88%-100%). Mobile data capture saved 1000 person-hours of transit and organizational time. Phone-based mobile data collection provided social support. Our results support this method for longitudinal studies among geographically and socially marginalized populations.
Collapse
|
22
|
Observation of WWW Production in pp Collisions at sqrt[s]=13 TeV with the ATLAS Detector. PHYSICAL REVIEW LETTERS 2022; 129:061803. [PMID: 36018638 DOI: 10.1103/physrevlett.129.061803] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/02/2022] [Accepted: 06/23/2022] [Indexed: 06/15/2023]
Abstract
This Letter reports the observation of WWW production and a measurement of its cross section using 139 fb^{-1} of proton-proton collision data recorded at a center-of-mass energy of 13 TeV by the ATLAS detector at the Large Hadron Collider. Events with two same-sign leptons (electrons or muons) and at least two jets, as well as events with three charged leptons, are selected. A multivariate technique is then used to discriminate between signal and background events. Events from WWW production are observed with a significance of 8.0 standard deviations, where the expectation is 5.4 standard deviations. The inclusive WWW production cross section is measured to be 820±100 (stat)±80 (syst) fb, approximately 2.6 standard deviations from the predicted cross section of 511±18 fb calculated at next-to-leading-order QCD and leading-order electroweak accuracy.
Collapse
|
23
|
A detailed map of Higgs boson interactions by the ATLAS experiment ten years after the discovery. Nature 2022; 607:52-59. [PMID: 35788192 PMCID: PMC9259483 DOI: 10.1038/s41586-022-04893-w] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2022] [Accepted: 05/23/2022] [Indexed: 11/16/2022]
Abstract
The standard model of particle physics1-4 describes the known fundamental particles and forces that make up our Universe, with the exception of gravity. One of the central features of the standard model is a field that permeates all of space and interacts with fundamental particles5-9. The quantum excitation of this field, known as the Higgs field, manifests itself as the Higgs boson, the only fundamental particle with no spin. In 2012, a particle with properties consistent with the Higgs boson of the standard model was observed by the ATLAS and CMS experiments at the Large Hadron Collider at CERN10,11. Since then, more than 30 times as many Higgs bosons have been recorded by the ATLAS experiment, enabling much more precise measurements and new tests of the theory. Here, on the basis of this larger dataset, we combine an unprecedented number of production and decay processes of the Higgs boson to scrutinize its interactions with elementary particles. Interactions with gluons, photons, and W and Z bosons-the carriers of the strong, electromagnetic and weak forces-are studied in detail. Interactions with three third-generation matter particles (bottom (b) and top (t) quarks, and tau leptons (τ)) are well measured and indications of interactions with a second-generation particle (muons, μ) are emerging. These tests reveal that the Higgs boson discovered ten years ago is remarkably consistent with the predictions of the theory and provide stringent constraints on many models of new phenomena beyond the standard model.
Collapse
|
24
|
Liraglutide treatment attenuates dysfunction-related changes in the cardiac and cerebral microvasculature in streptozotocin-induced diabetic rats. Cardiovasc Res 2022. [DOI: 10.1093/cvr/cvac066.234] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Abstract
Funding Acknowledgements
Type of funding sources: Foundation. Main funding source(s): Novo Nordisk
Background
Diabetes mellitus (DM) induces cardiac and cerebral microvascular dysfunction via increased glycation, oxidative stress and endothelial activation. Liraglutide, a glucagon-like peptide-1 receptor analogue, inhibited the reactive oxygen species producing enzyme NOX2 and adhesion molecules in isolated endothelial cells. Here we have studied how Liraglutide affects advanced glycation, NOX expression and inflammatory status of the cardiac and cerebral microvasculature in vivo in diabetic rats.
Methods
DM was induced in Sprague Dawley rats (n=15) via intraperitoneal streptozotocin (STZ) injection (60 mg/kg body weight). 10 control rats remained non-diabetic. From day 9 post-STZ injection, Liraglutide (200 µg/kg bodyweight; n=7) or vehicle (n=8) was injected subcutaneously daily until termination on day 29. The advanced glycation end-product N-ε-(carboxymethyl)lysine (CML), NOX2, NOX4, ICAM-1 and VCAM-1 were subsequently analysed using immunohistochemistry and quantified to compare Liraglutide treatment to placebo.
Results
DM increased CML, NOX2, ICAM-1 and VCAM-1 in the intramyocardial vasculature, although not significant for NOX2. NOX4 was not significantly increased in the ventricles and absent in the atria. In the cerebral vasculature, CML, NOX2 and NOX4 were significantly increased, but not ICAM-1 and VCAM-1. Liraglutide significantly reduced the DM-associated CML accumulation and expression of NOX2, ICAM-1 and VCAM-1 in the intramyocardial, and CML, NOX2 and NOX4 in the cerebral vasculature. Liraglutide had these effects without changing blood glucose levels or body weight.
Conclusions
Our study implies that Liraglutide protects the cardiac and cerebral microvasculature against diabetes-induced dysfunction, independent of a blood glucose lowering effect in a type 1 diabetes rat model.
Collapse
|
25
|
Search for Lepton-Flavor Violation in Z-Boson Decays with τ Leptons with the ATLAS Detector. PHYSICAL REVIEW LETTERS 2021; 127:271801. [PMID: 35061407 DOI: 10.1103/physrevlett.127.271801] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Accepted: 10/05/2021] [Indexed: 06/14/2023]
Abstract
A search for lepton-flavor-violating Z→eτ and Z→μτ decays with pp collision data recorded by the ATLAS detector at the LHC is presented. This analysis uses 139 fb^{-1} of Run 2 pp collisions at sqrt[s]=13 TeV and is combined with the results of a similar ATLAS search in the final state in which the τ lepton decays hadronically, using the same data set as well as Run 1 data. The addition of leptonically decaying τ leptons significantly improves the sensitivity reach for Z→ℓτ decays. The Z→ℓτ branching fractions are constrained in this analysis to B(Z→eτ)<7.0×10^{-6} and B(Z→μτ)<7.2×10^{-6} at 95% confidence level. The combination with the previously published analyses sets the strongest constraints to date: B(Z→eτ)<5.0×10^{-6} and B(Z→μτ)<6.5×10^{-6} at 95% confidence level.
Collapse
|
26
|
Search for New Phenomena in Final States with Two Leptons and One or No b-Tagged Jets at sqrt[s]=13 TeV Using the ATLAS Detector. PHYSICAL REVIEW LETTERS 2021; 127:141801. [PMID: 34652194 DOI: 10.1103/physrevlett.127.141801] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Accepted: 07/30/2021] [Indexed: 06/13/2023]
Abstract
A search for new phenomena is presented in final states with two leptons and one or no b-tagged jets. The event selection requires the two leptons to have opposite charge, the same flavor (electrons or muons), and a large invariant mass. The analysis is based on the full run-2 proton-proton collision dataset recorded at a center-of-mass energy of sqrt[s]=13 TeV by the ATLAS experiment at the LHC, corresponding to an integrated luminosity of 139 fb^{-1}. No significant deviation from the expected background is observed in the data. Inspired by the B-meson decay anomalies, a four-fermion contact interaction between two quarks (b, s) and two leptons (ee or μμ) is used as a benchmark signal model, which is characterized by the energy scale and coupling, Λ and g_{*}, respectively. Contact interactions with Λ/g_{*} lower than 2.0 (2.4) TeV are excluded for electrons (muons) at the 95% confidence level, still far below the value that is favored by the B-meson decay anomalies. Model-independent limits are set as a function of the minimum dilepton invariant mass, which allow the results to be reinterpreted in various signal scenarios.
Collapse
|
27
|
Search for Displaced Leptons in sqrt[s]=13 TeV pp Collisions with the ATLAS Detector. PHYSICAL REVIEW LETTERS 2021; 127:051802. [PMID: 34397238 DOI: 10.1103/physrevlett.127.051802] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/17/2020] [Revised: 03/03/2021] [Accepted: 06/11/2021] [Indexed: 06/13/2023]
Abstract
A search for charged leptons with large impact parameters using 139 fb^{-1} of sqrt[s]=13 TeV pp collision data from the ATLAS detector at the LHC is presented, addressing a long-standing gap in coverage of possible new physics signatures. Results are consistent with the background prediction. This search provides unique sensitivity to long-lived scalar supersymmetric lepton partners (sleptons). For lifetimes of 0.1 ns, selectron, smuon, and stau masses up to 720, 680, and 340 GeV, respectively, are excluded at 95% confidence level, drastically improving on the previous best limits from LEP.
Collapse
|
28
|
Abstract
Female genital fistula results in severe physical, psychological, and social sequelae. Qualitative research confirms stigma pervasiveness; however, no quantitative instrument exists to measure fistula-related stigma. We adapted an existing HIV-related stigma instrument to fistula-related stigma and assessed its reliability and validity. We recruited 60 Ugandan women seeking genital fistula surgery (December 2014-June 2015). We used exploratory factor analysis to explore the scale's latent structure and evaluated internal consistency reliability with Raykov's ρ statistic. We assessed construct validity through linear regression of stigma with quality of life, depressive symptoms and self-esteem. We retained 15 items across factors 'enacted stigma' and 'internalised stigma' (ρ = 0.960 and ρ = 0.748, respectively). Stigma was inversely associated with all quality of life domains; effect sizes were largest for environmental (enacted stigma, 0.69-point reduction) and psychological (internalised stigma, 0.67-point reduction) domains. Both stigma domains were associated positively with depressive symptoms and inversely with self-esteem, with 0.75 and 1.05-point increases in depressive symptoms and 0.45 and 0.77-point decreases in self-esteem for enacted and internalised stigma, respectively. Results suggest the reliability and validity of the adapted fistula stigma instrument. This instrument may help us understand stigma levels, compare stigma across individuals and communities, prioritise stigma-reduction strategies, and assess intervention impact.
Collapse
|
29
|
Longitudinal Flow Decorrelations in Xe+Xe Collisions at sqrt[s_{NN}]=5.44 TeV with the ATLAS Detector. PHYSICAL REVIEW LETTERS 2021; 126:122301. [PMID: 33834811 DOI: 10.1103/physrevlett.126.122301] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/14/2020] [Revised: 06/16/2020] [Accepted: 02/12/2021] [Indexed: 06/12/2023]
Abstract
The first measurement of longitudinal decorrelations of harmonic flow amplitudes v_{n} for n=2-4 in Xe+Xe collisions at sqrt[s_{NN}]=5.44 TeV is obtained using 3 μb^{-1} of data with the ATLAS detector at the LHC. The decorrelation signal for v_{3} and v_{4} is found to be nearly independent of collision centrality and transverse momentum (p_{T}) requirements on final-state particles, but for v_{2} a strong centrality and p_{T} dependence is seen. When compared with the results from Pb+Pb collisions at sqrt[s_{NN}]=5.02 TeV, the longitudinal decorrelation signal in midcentral Xe+Xe collisions is found to be larger for v_{2}, but smaller for v_{3}. Current hydrodynamic models reproduce the ratios of the v_{n} measured in Xe+Xe collisions to those in Pb+Pb collisions but fail to describe the magnitudes and trends of the ratios of longitudinal flow decorrelations between Xe+Xe and Pb+Pb. The results on the system-size dependence provide new insights and an important lever arm to separate effects of the longitudinal structure of the initial state from other early and late time effects in heavy-ion collisions.
Collapse
|
30
|
Search for Dark Matter Produced in Association with a Dark Higgs Boson Decaying into W^{±}W^{∓} or ZZ in Fully Hadronic Final States from sqrt[s]=13 TeV pp Collisions Recorded with the ATLAS Detector. PHYSICAL REVIEW LETTERS 2021; 126:121802. [PMID: 33834820 DOI: 10.1103/physrevlett.126.121802] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2020] [Accepted: 01/19/2021] [Indexed: 06/12/2023]
Abstract
Several extensions of the Standard Model predict the production of dark matter particles at the LHC. An uncharted signature of dark matter particles produced in association with VV=W^{±}W^{∓} or ZZ pairs from a decay of a dark Higgs boson s is searched for using 139 fb^{-1} of pp collisions recorded by the ATLAS detector at a center-of-mass energy of 13 TeV. The s→V(qq[over ¯])V(qq[over ¯]) decays are reconstructed with a novel technique aimed at resolving the dense topology from boosted VV pairs using jets in the calorimeter and tracking information. Dark Higgs scenarios with m_{s}>160 GeV are excluded.
Collapse
|
31
|
Medium-Induced Modification of Z-Tagged Charged Particle Yields in Pb+Pb Collisions at 5.02 TeV with the ATLAS Detector. PHYSICAL REVIEW LETTERS 2021; 126:072301. [PMID: 33666476 DOI: 10.1103/physrevlett.126.072301] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/25/2020] [Revised: 11/03/2020] [Accepted: 01/08/2021] [Indexed: 06/12/2023]
Abstract
The yield of charged particles opposite to a Z boson with large transverse momentum (p_{T}) is measured in 260 pb^{-1} of pp and 1.7 nb^{-1} of Pb+Pb collision data at 5.02 TeV per nucleon pair recorded with the ATLAS detector at the Large Hadron Collider. The Z boson tag is used to select hard-scattered partons with specific kinematics, and to observe how their showers are modified as they propagate through the quark-gluon plasma created in Pb+Pb collisions. Compared with pp collisions, charged-particle yields in Pb+Pb collisions show significant modifications as a function of charged-particle p_{T} in a way that depends on event centrality and Z boson p_{T}. The data are compared with a variety of theoretical calculations and provide new information about the medium-induced energy loss of partons in a p_{T} regime difficult to measure through other channels.
Collapse
|
32
|
Observation and Measurement of Forward Proton Scattering in Association with Lepton Pairs Produced via the Photon Fusion Mechanism at ATLAS. PHYSICAL REVIEW LETTERS 2020; 125:261801. [PMID: 33449771 DOI: 10.1103/physrevlett.125.261801] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2020] [Revised: 10/30/2020] [Accepted: 11/23/2020] [Indexed: 06/12/2023]
Abstract
The observation of forward proton scattering in association with lepton pairs (e^{+}e^{-}+p or μ^{+}μ^{-}+p) produced via photon fusion is presented. The scattered proton is detected by the ATLAS Forward Proton spectrometer, while the leptons are reconstructed by the central ATLAS detector. Proton-proton collision data recorded in 2017 at a center-of-mass energy of sqrt[s]=13 TeV are analyzed, corresponding to an integrated luminosity of 14.6 fb^{-1}. A total of 57 (123) candidates in the ee+p (μμ+p) final state are selected, allowing the background-only hypothesis to be rejected with a significance exceeding 5 standard deviations in each channel. Proton-tagging techniques are introduced for cross-section measurements in the fiducial detector acceptance, corresponding to σ_{ee+p}=11.0±2.6(stat)±1.2(syst)±0.3(lumi) and σ_{μμ+p}=7.2±1.6(stat)±0.9(syst)±0.2(lumi) fb in the dielectron and dimuon channel, respectively.
Collapse
|
33
|
Search for Heavy Resonances Decaying into a Photon and a Hadronically Decaying Higgs Boson in pp Collisions at sqrt[s]=13 TeV with the ATLAS Detector. PHYSICAL REVIEW LETTERS 2020; 125:251802. [PMID: 33416363 DOI: 10.1103/physrevlett.125.251802] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2020] [Accepted: 11/05/2020] [Indexed: 06/12/2023]
Abstract
This Letter presents a search for the production of new heavy resonances decaying into a Higgs boson and a photon using proton-proton collision data at sqrt[s]=13 TeV collected by the ATLAS detector at the LHC. The data correspond to an integrated luminosity of 139 fb^{-1}. The analysis is performed by reconstructing hadronically decaying Higgs boson (H→bb[over ¯]) candidates as single large-radius jets. A novel algorithm using information about the jet constituents in the center-of-mass frame of the jet is implemented to identify the two b quarks in the single jet. No significant excess of events is observed above the expected background. Upper limits are set on the production cross-section times branching fraction for narrow spin-1 resonances decaying into a Higgs boson and a photon in the resonance mass range from 0.7 to 4 TeV, cross-section times branching fractions are excluded between 11.6 fb and 0.11 fb at a 95% confidence level.
Collapse
|
34
|
Search for Higgs Boson Decays into a Z Boson and a Light Hadronically Decaying Resonance Using 13 TeV pp Collision Data from the ATLAS Detector. PHYSICAL REVIEW LETTERS 2020; 125:221802. [PMID: 33315463 DOI: 10.1103/physrevlett.125.221802] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Accepted: 10/09/2020] [Indexed: 06/12/2023]
Abstract
A search for Higgs boson decays into a Z boson and a light resonance in two-lepton plus jet events is performed, using a pp collision dataset with an integrated luminosity of 139 fb^{-1} collected at sqrt[s]=13 TeV by the ATLAS experiment at the CERN LHC. The resonance considered is a light boson with a mass below 4 GeV from a possible extended scalar sector or a charmonium state. Multivariate discriminants are used for the event selection and for evaluating the mass of the light resonance. No excess of events above the expected background is found. Observed (expected) 95% confidence-level upper limits are set on the Higgs boson production cross section times branching fraction to a Z boson and the signal resonance, with values in the range 17-340 pb (16_{-5}^{+6}-320_{-90}^{+130} pb) for the different light spin-0 boson mass and branching fraction hypotheses, and with values of 110 and 100 pb (100_{-30}^{+40} and 100_{-30}^{+40} pb) for the η_{c} and J/ψ hypotheses, respectively.
Collapse
|
35
|
Dijet Resonance Search with Weak Supervision Using sqrt[s]=13 TeV pp Collisions in the ATLAS Detector. PHYSICAL REVIEW LETTERS 2020; 125:131801. [PMID: 33034503 DOI: 10.1103/physrevlett.125.131801] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/07/2020] [Revised: 07/12/2020] [Accepted: 08/04/2020] [Indexed: 05/11/2023]
Abstract
This Letter describes a search for narrowly resonant new physics using a machine-learning anomaly detection procedure that does not rely on signal simulations for developing the analysis selection. Weakly supervised learning is used to train classifiers directly on data to enhance potential signals. The targeted topology is dijet events and the features used for machine learning are the masses of the two jets. The resulting analysis is essentially a three-dimensional search A→BC, for m_{A}∼O(TeV), m_{B},m_{C}∼O(100 GeV) and B, C are reconstructed as large-radius jets, without paying a penalty associated with a large trials factor in the scan of the masses of the two jets. The full run 2 sqrt[s]=13 TeV pp collision dataset of 139 fb^{-1} recorded by the ATLAS detector at the Large Hadron Collider is used for the search. There is no significant evidence of a localized excess in the dijet invariant mass spectrum between 1.8 and 8.2 TeV. Cross-section limits for narrow-width A, B, and C particles vary with m_{A}, m_{B}, and m_{C}. For example, when m_{A}=3 TeV and m_{B}≳200 GeV, a production cross section between 1 and 5 fb is excluded at 95% confidence level, depending on m_{C}. For certain masses, these limits are up to 10 times more sensitive than those obtained by the inclusive dijet search. These results are complementary to the dedicated searches for the case that B and C are standard model bosons.
Collapse
|
36
|
Abstract
Female genital fistula results in severe physical, psychological, and social sequelae. Qualitative research confirms stigma pervasiveness; however, no quantitative instrument exists to measure fistula-related stigma. We adapted an existing HIV-related stigma instrument to fistula-related stigma and assessed its reliability and validity. We recruited 60 Ugandan women seeking genital fistula surgery (December 2014-June 2015). We used exploratory factor analysis to explore the scale's latent structure and evaluated internal consistency reliability with Raykov's ρ statistic. We assessed construct validity through linear regression of stigma with quality of life, depressive symptoms and self-esteem. We retained 15 items across factors 'enacted stigma' and 'internalised stigma' (ρ = 0.960 and ρ = 0.748, respectively). Stigma was inversely associated with all quality of life domains; effect sizes were largest for environmental (enacted stigma, 0.69-point reduction) and psychological (internalised stigma, 0.67-point reduction) domains. Both stigma domains were associated positively with depressive symptoms and inversely with self-esteem, with 0.75 and 1.05-point increases in depressive symptoms and 0.45 and 0.77-point decreases in self-esteem for enacted and internalised stigma, respectively. Results suggest the reliability and validity of the adapted fistula stigma instrument. This instrument may help us understand stigma levels, compare stigma across individuals and communities, prioritise stigma-reduction strategies, and assess intervention impact.
Collapse
|
37
|
Search for heavy neutral Higgs bosons produced in association with
b
-quarks and decaying into
b
-quarks at
s=13 TeV
with the ATLAS detector. Int J Clin Exp Med 2020. [DOI: 10.1103/physrevd.102.032004] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
|
38
|
CP Properties of Higgs Boson Interactions with Top Quarks in the tt[over ¯]H and tH Processes Using H→γγ with the ATLAS Detector. PHYSICAL REVIEW LETTERS 2020; 125:061802. [PMID: 32845699 DOI: 10.1103/physrevlett.125.061802] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2020] [Accepted: 06/15/2020] [Indexed: 06/11/2023]
Abstract
A study of the charge conjugation and parity (CP) properties of the interaction between the Higgs boson and top quarks is presented. Higgs bosons are identified via the diphoton decay channel (H→γγ), and their production in association with a top quark pair (tt[over ¯]H) or single top quark (tH) is studied. The analysis uses 139 fb^{-1} of proton-proton collision data recorded at a center-of-mass energy of sqrt[s]=13 TeV with the ATLAS detector at the Large Hadron Collider. Assuming a CP-even coupling, the tt[over ¯]H process is observed with a significance of 5.2 standard deviations. The measured cross section times H→γγ branching ratio is 1.64_{-0.36}^{+0.38}(stat)_{-0.14}^{+0.17}(sys) fb, and the measured rate for tt[over ¯]H is 1.43_{-0.31}^{+0.33}(stat)_{-0.15}^{+0.21}(sys) times the Standard Model expectation. The tH production process is not observed and an upper limit on its rate of 12 times the Standard Model expectation is set. A CP-mixing angle greater (less) than 43 (-43)° is excluded at 95% confidence level.
Collapse
|
39
|
Search for Heavy Higgs Bosons Decaying into Two Tau Leptons with the ATLAS Detector Using pp Collisions at sqrt[s]=13 TeV. PHYSICAL REVIEW LETTERS 2020; 125:051801. [PMID: 32794886 DOI: 10.1103/physrevlett.125.051801] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2020] [Accepted: 06/26/2020] [Indexed: 06/11/2023]
Abstract
A search for heavy neutral Higgs bosons is performed using the LHC Run 2 data, corresponding to an integrated luminosity of 139 fb^{-1} of proton-proton collisions at sqrt[s]=13 TeV recorded with the ATLAS detector. The search for heavy resonances is performed over the mass range 0.2-2.5 TeV for the τ^{+}τ^{-} decay with at least one τ-lepton decaying into final states with hadrons. The data are in good agreement with the background prediction of the standard model. In the M_{h}^{125} scenario of the minimal supersymmetric standard model, values of tanβ>8 and tanβ>21 are excluded at the 95% confidence level for neutral Higgs boson masses of 1.0 and 1.5 TeV, respectively, where tanβ is the ratio of the vacuum expectation values of the two Higgs doublets.
Collapse
|
40
|
Measurement of the Lund Jet Plane Using Charged Particles in 13 TeV Proton-Proton Collisions with the ATLAS Detector. PHYSICAL REVIEW LETTERS 2020; 124:222002. [PMID: 32567910 DOI: 10.1103/physrevlett.124.222002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/08/2020] [Revised: 05/06/2020] [Accepted: 05/13/2020] [Indexed: 06/11/2023]
Abstract
The prevalence of hadronic jets at the LHC requires that a deep understanding of jet formation and structure is achieved in order to reach the highest levels of experimental and theoretical precision. There have been many measurements of jet substructure at the LHC and previous colliders, but the targeted observables mix physical effects from various origins. Based on a recent proposal to factorize physical effects, this Letter presents a double-differential cross-section measurement of the Lund jet plane using 139 fb^{-1} of sqrt[s]=13 TeV proton-proton collision data collected with the ATLAS detector using jets with transverse momentum above 675 GeV. The measurement uses charged particles to achieve a fine angular resolution and is corrected for acceptance and detector effects. Several parton shower Monte Carlo models are compared with the data. No single model is found to be in agreement with the measured data across the entire plane.
Collapse
|
41
|
Rehabilitation and reintegration programming adjunct to female genital fistula surgery: A systematic scoping review. Int J Gynaecol Obstet 2020; 148 Suppl 1:42-58. [PMID: 31943181 PMCID: PMC7003948 DOI: 10.1002/ijgo.13039] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
BACKGROUND Female genital fistula is associated with significant physical, psychological, and economic consequences; however, a knowledge and practice gap exists around services adjunct to fistula surgery. OBJECTIVES To examine rehabilitation and reintegration services provided adjunct to genital fistula surgery, map existing programming and outcomes, and identify areas for additional research. SEARCH STRATEGY We searched the published and grey literature from January 2000 to June 2019. Two reviewers screened articles and extracted data using standardized methods. SELECTION CRITERIA Research and programmatic articles describing service provision in addition to female genital fistula surgery were included. DATA COLLECTION AND ANALYSIS Of 3047 published articles and 2623 unpublished documents identified, 26 and 55, respectively, were analyzed. MAIN RESULTS Programming identified included combinations of health education, physical therapy, social support, psychosocial counseling, and economic empowerment, largely in sub-Saharan Africa. Improvements were noted in physical and psychosocial health. CONCLUSIONS Existing literature supports holistic fistula care through adjunct reintegration programming. Improving the evidence base requires implementing robust study designs, increasing reporting detail, and standardizing outcomes across studies. Increased financing for holistic fistula care is critical for developing and supporting programming to ensure positive outcomes.
Collapse
|
42
|
Women's experiences of fistula-related stigma in Uganda: a conceptual framework to inform stigma-reduction interventions. CULTURE, HEALTH & SEXUALITY 2020; 22:352-367. [PMID: 31035913 PMCID: PMC6821552 DOI: 10.1080/13691058.2019.1600721] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/08/2018] [Accepted: 03/25/2019] [Indexed: 05/26/2023]
Abstract
Fistula-related stigma is common. The absence of a unifying conceptual framework prevents a nuanced understanding of the nature of fistula-related stigma, comparison across contexts and the ability to contrast with other stigmas. It also hinders intervention development. We conducted in-depth interviews or focus groups with 60 women who had undergone fistula surgery 6-24 months prior at Mulago Hospital in Kampala, Uganda in 2014. Transcripts were analysed for experiences and consequences of enacted, anticipated and internalised stigma. Narratives revealed experiences with enacted stigma, including gossip, verbal abuse and social exclusion. Women also anticipated and feared stigma in the future. Internalised stigma reports revealed shame and low self-esteem: self-worth reduction, feeling disgraced and envisioning no future. Consequences included social isolation, changes to normal activities, non-disclosure and poor mental health. Refining stigma theory to specific conditions has resulted in a more nuanced understanding of stigma dimensions, manifestations, mechanisms and consequences, permitting comparison across contexts and populations and the development of stigma-reduction interventions. These lessons should be applied to fistula, acknowledging unique features: concealability, the potential for treatment, lack of community awareness and the social consequences of stillbirth. Reducing fistula-related stigma requires timely surgery and supportive care, stigma-reduction interventions and addressing the complex societal structures that perpetuate fistula.
Collapse
|
43
|
Measurement of Azimuthal Anisotropy of Muons from Charm and Bottom Hadrons in pp Collisions at sqrt[s]=13 TeV with the ATLAS Detector. PHYSICAL REVIEW LETTERS 2020; 124:082301. [PMID: 32167369 DOI: 10.1103/physrevlett.124.082301] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/05/2019] [Revised: 11/29/2019] [Accepted: 01/22/2020] [Indexed: 06/10/2023]
Abstract
The elliptic flow of muons from the decay of charm and bottom hadrons is measured in pp collisions at sqrt[s]=13 TeV using a data sample with an integrated luminosity of 150 pb^{-1} recorded by the ATLAS detector at the LHC. The muons from heavy-flavor decay are separated from light-hadron decay muons using momentum imbalance between the tracking and muon spectrometers. The heavy-flavor decay muons are further separated into those from charm decay and those from bottom decay using the distance-of-closest-approach to the collision vertex. The measurement is performed for muons in the transverse momentum range 4-7 GeV and pseudorapidity range |η|<2.4. A significant nonzero elliptic anisotropy coefficient v_{2} is observed for muons from charm decays, while the v_{2} value for muons from bottom decays is consistent with zero within uncertainties.
Collapse
|
44
|
Search for Magnetic Monopoles and Stable High-Electric-Charge Objects in 13 Tev Proton-Proton Collisions with the ATLAS Detector. PHYSICAL REVIEW LETTERS 2020; 124:031802. [PMID: 32031842 DOI: 10.1103/physrevlett.124.031802] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/27/2019] [Revised: 11/26/2019] [Indexed: 06/10/2023]
Abstract
A search for magnetic monopoles and high-electric-charge objects is presented using 34.4 fb^{-1} of 13 TeV pp collision data collected by the ATLAS detector at the LHC during 2015 and 2016. The considered signature is based upon high ionization in the transition radiation tracker of the inner detector associated with a pencil-shape energy deposit in the electromagnetic calorimeter. The data were collected by a dedicated trigger based on the tracker high-threshold hit capability. The results are interpreted in models of Drell-Yan pair production of stable particles with two spin hypotheses (0 and 1/2) and masses ranging from 200 to 4000 GeV. The search improves by approximately a factor of 5 the constraints on the direct production of magnetic monopoles carrying one or two Dirac magnetic charges and stable objects with electric charge in the range 20≤|z|≤60 and extends the charge range to 60<|z|≤100.
Collapse
|
45
|
Combined measurements of Higgs boson production and decay using up to
80 fb−1
of proton-proton collision data at
s=13 TeV
collected with the ATLAS experiment. Int J Clin Exp Med 2020. [DOI: 10.1103/physrevd.101.012002] [Citation(s) in RCA: 178] [Impact Index Per Article: 44.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
|
46
|
Observation of Electroweak Production of a Same-Sign W Boson Pair in Association with Two Jets in pp Collisions at sqrt[s]=13 TeV with the ATLAS Detector. PHYSICAL REVIEW LETTERS 2019; 123:161801. [PMID: 31702349 DOI: 10.1103/physrevlett.123.161801] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/10/2019] [Indexed: 06/10/2023]
Abstract
This Letter presents the observation and measurement of electroweak production of a same-sign W boson pair in association with two jets using 36.1 fb^{-1} of proton-proton collision data recorded at a center-of-mass energy of sqrt[s]=13 TeV by the ATLAS detector at the Large Hadron Collider. The analysis is performed in the detector fiducial phase-space region, defined by the presence of two same-sign leptons, electron or muon, and at least two jets with a large invariant mass and rapidity difference. A total of 122 candidate events are observed for a background expectation of 69±7 events, corresponding to an observed signal significance of 6.5 standard deviations. The measured fiducial signal cross section is σ^{fid}=2.89_{-0.48}^{+0.51}(stat)_{-0.28}^{+0.29}(syst) fb.
Collapse
|
47
|
Abstract
INTRODUCTION Female genital fistula is a debilitating traumatic injury, largely birth-associated, globally affecting up to 2 million women, mostly in sub-Saharan Africa. Fistula has significant physical, psychological and economic consequences. Women often face challenges in reintegrating and resuming prior roles despite successful surgery. Synthesising the evidence on services adjunct to fistula surgery and their outcomes is important for developing the evidence base for best practices and identifying research priorities. This scoping review seeks to examine the range of rehabilitation and reintegration services provided as adjunct to genital fistula surgery, map the existing programming and outcomes, and identify areas for additional research. METHODS AND ANALYSIS Our scoping review is informed by existing methodological frameworks and will be conducted in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses-ScR guidelines. The search strategy will be applied to nine biomedical, public health and social science databases. The initial search was completed on 27 September 2018. Grey literature will be identified through targeted Google searches and from organisational websites identified as relevant by the United Nations Population Fund (UNFPA) Campaign to End Fistula. We will iteratively build our search strategy through term harvesting and review, and search reference lists of reports and articles to identify additional studies. Two reviewers will independently screen titles and abstracts, followed by full-text screening of all potentially relevant articles and standardised data extraction. Articles eligible for inclusion will discuss research or programmatic efforts around service provision in adjunct to surgery among females with genital fistula. Data will be presented in summary tables accompanied by narrative description. ETHICS AND DISSEMINATION Ethics approval is not required for a scoping review. Our results can be used to inform policy, serve as support for funding and development of reintegration programmes and highlight areas for subsequent research. Results will be disseminated at relevant conferences and published in a peer-reviewed journal.
Collapse
|
48
|
P04.06 The incidence and impact of post-operative stroke in surgery for LGG. Neuro Oncol 2019. [DOI: 10.1093/neuonc/noz126.101] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Abstract
BACKGROUND: INTRODUCTION
Postoperative neurological deficits may outweigh the benefit conferred by maximal resection of gliomas. Ischemic complications are a common cause of such deficits. In this study, we evaluated the incidence of ischemic events in patients undergoing surgery for low-grade gliomas (LGG) and the long-term neurological and cognitive implications of those events.
METHODS
Between 2013–2017, 168 patients underwent surgical resection or biopsy for LGG at our center. A full dataset, including pre- and postoperative magnetic resonance imaging (MRI) and long-term clinical evaluation findings, was available in 82 patients that underwent resection, and they comprised our study cohort. We retrospectively analyzed pre- and postoperative demographic, clinical, radiological, anesthetic, and intraoperative neurophysiology data to characterize associated ischemic complications. Overall and progression-free survival, as well as functional and neurocognitive outcomes were evaluated as well.
RESULTS
The immediate postoperative MRI showed evidence of an acute ischemic stroke adjacent to the tumor resection cavity in 19 patients (23%), 13 of whom developed new neurological deficits as a result of the ischemic event. Infarcts were more common in patients undergoing surgery for a recurrent tumor, especially those involving the Sylvian fissure (p<0.05). Surgery for insular gliomas had the strongest association with postoperative infarcts (multivariate analysis: odds ratio =12.4, 95% confidence interval 2.21–69.8). There was no difference in survival between patients with or without a postoperative infarct. The median Karnofsky Performance Status was lower for the infarct group compared to the non-infarct group at 3 months after surgery (p=0.016), with a gradual significant improvement for the former over one year of follow-up (p=0.04). Immediately after surgery, 27% of the patients without infarcts and 58% of those with infarcts experienced a new motor deficit (p=0.037), decreasing to 16% (p=0.028) and 37% (p=0.001), respectively, at one year. Neurocognitive analysis findings before and 3 months after surgery were unchanged, but there was a significant decrease in naming in patients who experienced an infarct (NeuroTrax computerized battery score of 100±9 and 83±19, p=0.04 respectively). Confusion during awake craniotomy was a strong predictor of the occurrence of an ischemic stroke.
CONCLUSIONS
Intraoperative strokes are more prevalent among patients who undergo recurrent surgeries, especially procedures in the insula. Although they do not affect survival, these strokes negatively affect the patients’ activity and performance status, especially during the first 3 postoperative months, with gradual functional improvement over one year.
Collapse
|
49
|
Observation of Light-by-Light Scattering in Ultraperipheral Pb+Pb Collisions with the ATLAS Detector. PHYSICAL REVIEW LETTERS 2019; 123:052001. [PMID: 31491300 DOI: 10.1103/physrevlett.123.052001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/11/2019] [Indexed: 06/10/2023]
Abstract
This Letter describes the observation of the light-by-light scattering process, γγ→γγ, in Pb+Pb collisions at sqrt[s_{NN}]=5.02 TeV. The analysis is conducted using a data sample corresponding to an integrated luminosity of 1.73 nb^{-1}, collected in November 2018 by the ATLAS experiment at the LHC. Light-by-light scattering candidates are selected in events with two photons produced exclusively, each with transverse energy E_{T}^{γ}>3 GeV and pseudorapidity |η_{γ}|<2.4, diphoton invariant mass above 6 GeV, and small diphoton transverse momentum and acoplanarity. After applying all selection criteria, 59 candidate events are observed for a background expectation of 12±3 events. The observed excess of events over the expected background has a significance of 8.2 standard deviations. The measured fiducial cross section is 78±13(stat)±7(syst)±3(lumi) nb.
Collapse
|
50
|
Comparison of Fragmentation Functions for Jets Dominated by Light Quarks and Gluons from pp and Pb+Pb Collisions in ATLAS. PHYSICAL REVIEW LETTERS 2019; 123:042001. [PMID: 31491254 DOI: 10.1103/physrevlett.123.042001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2019] [Revised: 05/21/2019] [Indexed: 06/10/2023]
Abstract
Charged-particle fragmentation functions for jets azimuthally balanced by a high-transverse-momentum, prompt, isolated photon are measured in 25 pb^{-1} of pp and 0.49 nb^{-1} of Pb+Pb collision data at 5.02 TeV per nucleon pair recorded with the ATLAS detector at the Large Hadron Collider. The measurements are compared to predictions of Monte Carlo generators and to measurements of inclusively selected jets. In pp collisions, a different jet fragmentation function in photon-tagged events from that in inclusive jet events arises from the difference in fragmentation between light quarks and gluons. The ratios of the fragmentation functions in Pb+Pb events to that in pp events are used to explore the parton color-charge dependence of jet quenching in the hot medium. In relatively peripheral collisions, fragmentation functions exhibit a similar modification pattern for photon-tagged and inclusive jets. However, photon-tagged jets are observed to have larger modifications than inclusive jets in central Pb+Pb events.
Collapse
|