Measurement of the Lund Jet Plane Using Charged Particles in 13 TeV Proton-Proton Collisions with the ATLAS Detector

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.

AB1124 USEFULNESS OF SUPERB MICRO-VASCULAR IMAGING(SMI) TO DETECT SILENT VASCULITIC DISEASE ACTIVITY IN 2 CASES OF TAKAYASU ARTERITIS

Background:

It is important to use vascular imaging modalities such as CT, MRI and PET-CT to evaluate disease activity of Takayasu arteritis (TAK). In particular, under treatment with tocilizumab (TCZ), redsidual vasculitic disease activity may remain even if serum CRP becomes negative. Contrast-enhanced CT,MRI and PET-CT can evaluate the morphology of blood vessel walls and the distribution of lesions and vasculitic activity, but it is invasive (radiation or contract media exposure), and costly. Ultrasound is superior in terms of morphological evaluation, cost, convenience, and low invasiveness. In particular, Superb Micro-vascular Imaging(SMI) is one of the micro blood flow display methods that can be installed in the ultrasound diagnostic device Aplio series.

There are some case reports in which micro blood flow signals of the carotid artery walls were detected using SMI in Takayasu arteritis [1] [2]. Both reports indicate that SMI blood flow is a comparable indicator of disease activity as serum CRP.

Objectives:

To report the usefulness of SMI in 2 TAK patients who had negative serum CRP but had residual disease activity, leading to appropriate adjustment of treatment.

Methods:

Two TAK patients who had been newly diagnosed in our department from May 2015 to October 2018 and had received SMI to detect carotid artery wall blood flow signal were retrospectively analyzed.

Results:

Case 1

A 32-year-old woman developed neck pain, headaches, fever and she had high serum levels of CRP (8.1 mg/dl) and elevated ESR (98 mm/h). Contrast-enhanced CT showed thickening of the carotid artery, left subclavian artery and thoracic aorta and SMI detected blood flow signal in carotid artery wall. Diagnosis of TAK was made. After 2-week treatment with 1 mg/kg/day of PSL, CRP became negative but the micro blood flow in carotid arterity walls was detedted by SMI. Therefore,subcutaneous TCZ (162 mg/week)was added in combination with PSL.One year later, micro blood flow disappeared and we could judge there was no vasculitis activity (Figure A).

Before treatment starts2 weeks after starting treatmentOne year after starting treatmenttreatment-PSL 1mg/kg/day ongoingPSL 7mg/day ongoingTCZ 162 mg/week ongoingCRP(mg/dl)+ (8.1)−(0.0)−(0.0)SMI signal++−Figure 1.

A. Clinical course of Case 1

Case 2

A 17-year-old woman developed proximal upper limb pain and fever with high serum CRP levels (7.1 mg/dl) and elevated ESR (>110 mm/h), and contrast-enhanced CT showed thickening of the carotid arteries and aortic arch. Two weeks after the start of PSL (1 mg/kg/day), CRP became negative at 0.3 mg/dl, but intramural blood flow detected by SMI remained. Then subcutaneous TCZ was added. Two weeks later, CRP became negative, and the SMI blood flow also disappeared (Figure B).

Before treatment starts2 weeks after starting treatment4 weeks after starting treatmenttreatment-PSL 1mg/kg/day ongoingPSL 50 mg/day ongoingTCZ 162 mg/week addedCRP(mg/dl)+ (7.1)−(0.3)−(0.0)SMI signal++−Figure 2.

B. Clinical course of Case 2

Conclusion:

Although SMI has the limitation that it cannot evaluate deep vascular lesions such as aorta, it is neither invasive nor costly and may be a good tool for evaluation of residual vasculitis activity of TAK.

References:

[1]Sato W, Sato T, Iino T, Seki K, Watanabe H. Visualization of arterial wall vascularization using superb microvascular imaging in active-stage Takayasu arteritis.European Heart Journal - Cardiovascular Imaging. 2019;20(6):719

[2]Ito S, Tahara N, Hirakata S, et al. Signal intensity of superb micro-vascular imaging associates with the activity of vascular inflammation in Takayasu arteritis.Journal of Nuclear Cardiology:Official Publication of the American Society of Nuclear Cardiology. 2019 Mar DOI: 10.1007/s12350-019-01665-4.

Acknowledgments:

We thank Minako.Yamashita and Masahiro.setoyama for her technical assistance to conduct SMI.

Disclosure of Interests:

None declared

Effect of high ligation on survival of patients undergoing surgery for primary colorectal cancer and synchronous liver metastases

Background

Although R0 surgery is recommended for stage IV colorectal cancer, the degree of required lymphadenectomy has not been established. The aim of this study was to investigate the prognostic impact of high ligation (HL) of the feeding artery and the number of retrieved lymph nodes after R0 surgery for colorectal cancer and synchronous colorectal cancer liver metastasis (CRLM).

Methods

This was a multi‐institutional retrospective analysis of patients with colorectal cancer and synchronous CRLM who had R0 surgery between January 1997 and December 2007. Clinical and pathological features were compared in patients who underwent HL and those who had a low ligation (LL). Kaplan–Meier analysis was performed to estimate the effect of HL on overall survival (OS). The impact of several risk factors on survival was analysed using the Cox proportional hazards model.

Results

Of 549 patients, 409 (74·5 per cent) had HL. Median follow‐up was 51·4 months. HL significantly improved the 5‐year OS rate (58·2 per cent versus 49·3 per cent for LL; P = 0·017). Multivariable analysis revealed HL to be a significant prognostic factor compared with LL (5‐year mortality: hazard ratio (HR) 0·68, 95 per cent c.i. 0·51 to 0·90; P = 0·007). In subgroup analysis, the positive effect of HL on OS was greatest in patients with lymph node metastasis.

Conclusion

HL of the feeding artery was associated with improved OS in patients with colorectal cancer and synchronous CRLM after R0 surgery.

Measurement of Azimuthal Anisotropy of Muons from Charm and Bottom Hadrons in pp Collisions at sqrt[s]=13 TeV with the ATLAS Detector

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.

Search for Magnetic Monopoles and Stable High-Electric-Charge Objects in 13 Tev Proton-Proton Collisions with the ATLAS Detector

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.

Pyogenic spondylitis with acute course caused by Corynebacterium simulans

Corynebacterium simulans was first reported in 2000. Although it is a member of the normal skin flora, some cases of C. simulans infection have been reported. Other Corynebacterium spp. rarely cause chronic pyogenic spondylitis, and pyogenic spondylitis caused by C. simulans has not been reported at all. Here we report a case of acute pyogenic spondylitis due to C. simulans. A 78-year-old man with diabetes mellitus visited our hospital with a 3-day history of lower back pain and fever. Blood culture revealed C. simulans and magnetic resonance images of lumbar vertebrae showed pyogenic spondylitis. He recovered after treatment by vancomycin for 9 weeks and was discharged home. No recurrence has been observed for half a year. This is likely the first reported case of pyogenic spondylitis by C. simulans. In general, Corynebacterium spp. cause chronic pyogenic spondylitis, but this case showed an acute course.

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

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.

P1259Right atrial low voltage zone as a novel predictor of sinus node dysfunction in patients with non-paroxysmal atrial fibrillation

Background

Although sinus node dysfunction (SND) coexists with atrial fibrillation (AF) in some cases, SND in patients with Non-paroxysmal AF (Non-PAF) could not be estimated in conventional electrophysiological study.

Atrial low voltage zone (LVZ), which may be surrogate for atrial fibrosis, is although reported to present in patients with Non-PAF, the association between SND and right atrial LVZ (RA-LVZ) has not been fully evaluated. The aim of the present study was to assess the relationship between SND and RA-LVZ in patients with Non-PAF.

Method

Eighty-six Non-PAF patients underwent high density voltage mapping of right atrium (RA) during AF before ablation procedure. We defined LVZ as that with electrogram amplitude <0.1 mV in order to delineate strongly damaged area in RA. We evaluated the surface are of the RA-LVZ in Non-PAF patients with and without SND.

Results

Twenty-seven of 86 patients (31.4%) presented with SND after AF termination. There were no significant differences between patients with and without SND in variables such as age, sex, AF duration, left atrial diameter, and left ventricular ejection fraction. The mean value of RA-LVZ of all the patients was 12.1±11.4%, and RA-LVZ was significantly larger in patients with SND than in those without SND (22.8±14.6 vs 7.2±4.2%; P<0.001). In multivariate logistic regression analysis for the incidence of subsequent pacemaker implantation (PMI), only RA-LVZ was a significant predictor of subsequent PMI (odd ratio 1.306; 95% confidence interval 1.159 - 1.473; P<0.001). Receiving-operating characteristic curve for PMI following ablation procedure indicated cut-off value 10.5% for RA-LVZ with 85.2% sensitivity and 88.1% specificity (area under curve = 0.924, P<0.001). Kaplan-Meier analysis of the incidence of PMI after AF termination showed that freedom from pacemaker implantation was significantly better in patients with RA-LVA <10.5% than in those with RA-LVZ ≥10.5% (log-rank test; P<0.001).

Conclusions

Broad RA-LVZ measured during AF was strongly associated with SND and PMI after AF termination in patients with Non-PAF. Evaluation of RA-LVZ during AF could be a potential target in predicting SND requiring PMI in patients with Non-PAF.

P3718Identification of nine genes as novel susceptibility loci for early-onset ischemic stroke, intracerebral hemorrhage, or subarachnoid hemorrhage

Background

Given that substantial genetic components have been shown in ischemic stroke, intracerebral hemorrhage (ICH), and subarachnoid hemorrhage (SAH), a heritability may be higher in early-onset than late-onset individuals with these conditions. Although genome-wide association studies have identified various genes and loci significantly associated with ischemic stroke, ICH, or intracranial aneurysm mainly in European ancestry populations, genetic variants that contribute to susceptibility to these disorders in Japanese individuals remain to be identified definitively.

Purpose

The purpose of the study was to identify genetic variants that confer susceptibility to ischemic stroke, ICH, or SAH in Japanese. We have now performed exome-wide association studies (EWASs) in early-onset subjects with these conditions and corresponding controls.

Methods

A total of 6649 individuals aged ≤65 years were examined. For the EWAS of ischemic or hemorrhagic stroke, 6224 individuals (450 subjects with ischemic stroke, 5774 controls) or 6179 individuals (261 subjects with ICH, 176 subjects with SAH, 5742 controls), respectively, were examined. EWASs were performed with the use of Illumina Human Exome-12 v1.2 DNA Analysis BeadChip or Infinium Exome-24 v1.0 BeadChip. To compensate for multiple comparisons of allele frequencies with ischemic stroke, ICH, or SAH, we applied a false discovery rate (FDR) of <0.05 for statistical significance of association.

Results

The relation of allele frequencies of 31,245 single nucleotide polymorphisms (SNPs) that passed quality control to ischemic stroke was examined with Fisher's exact test, and 31 SNPs were significantly (FDR <0.05) associated with ischemic stroke. The relation of allele frequencies of 31,253 or 30,970 SNPs to ICH or SAH, respectively, was examined with Fisher's exact test, and six or two SNPs were significantly (FDR <0.05) associated with ICH or SAH, respectively. Multivariable logistic regression analysis with adjustment for age, sex, and the prevalence of hypertension and diabetes mellitus revealed that 12 SNPs were significantly [P <0.0004 (Bonferroni's correction, 0.05/124)] related to ischemic stroke. Similar analysis with adjustment for age, sex, and the prevalence of hypertension revealed that six or two SNPs were significantly [P <0.0016 (0.05/32)] related to ICH or SAH, respectively. After examination of linkage disequilibrium of identified SNPs and results of previous genome-wide association studies, we have newly identified HHIPL2, CTNNA3, LOC643770, UTP20, and TRIB3 as susceptibility loci for ischemic stroke, DNTTIP2 and FAM205A as susceptibility loci for ICH, and FAM160A1 and OR52E4 as such loci for SAH.

Conclusion

We have thus newly identified nine genes that confer susceptibility to early-onset ischemic stroke, ICH, or SAH. Determination of genotypes for the SNPs in these genes may prove informative for assessment of the genetic risk for ischemic stroke, ICH, or SAH in Japanese.

P6452Circulating human epididymis protein 4 is a novel prognostic predictor in ambulatory patients with non-ischemic dilated cardiomyopathy

Background

Myofibroblasts, which are activated fibroblasts, play an important role in interstitial fibrosis in non-ischemic dilated cardiomyopathy (NIDCM). Recently, human epididymal body protein 4 (HE4) has attracted attention as a marker specific to myofibroblasts. However, the prognostic impact of HE-4 on cardiovascular events in NIDCM patients has not been reported.

Purposes

The purpose of this study was to investigate the impact of circulating serum HE4 on the prognosis in patients with NIDCM.

Methods

Forty-four NIDCM patients underwent echocardiography, laboratory measurements, cardiac catheterization, and endomyocardial biopsy within one week under stable heart failure condition. Patients with cancer were excluded from this study. We collected blood samples from peripheral vain, ascending aorta, and coronary sinus during cardiac catheterization and measured serum HE4 level. They were divided into two groups at the median of HE4 level: High-HE4 group (HE4 >69 pmol/L); n=22, Low-HE4 group (HE4 <69 pmol/L); n=22. Cardiac composite event was defined as cardiac related deaths and hospitalization due to worsening heart failure.

Results

The mean age, left ventricular ejection fraction (LVEF), and plasma brain natriuretic peptide level were 56 years, 32%, and 205 pg/mL. Between two groups, there were no significant differences in age, gender, LVEF, left ventricular end-diastolic diameter, cardiac index, and pulmonary capillary wedge pressure. However, estimated glomerular filtration rate was significantly lower in the High-HE4 group (p=0.025). Kaplan-Meier survival analysis revealed that the High-HE group had a higher rate of cardiac composite event (p=0.011, see Figure). However, as for the pathological analysis, not only the peripheral HE4 level but also HE4 value subtracting coronary sinus from ascending aorta did not significantly correlate with collagen volume fraction in biopsy samples.

Circulating HE4 level and prognosis

Conclusion

Elevated circulating HE4 is associcated with poor prognosis in ambulatory patients with NIDCM.

P3576Histopathological validation of optical coherence tomography assessment for cholesterol crystals

Background

Cholesterol crystals (CCs) are well recognized as one of important components of advanced atherosclerotic plaques. Whilethe consensus document for intravascular optical coherence tomography (OCT) has proposed that CCs are appeared as thin, linear regions of high-signal intensity within a plaque, no study has validated CCs assessment by OCT in comparison with histopathology.

Purpose

Thepurpose of this study was to validate OCT assessments of CCs with histopathology.

Methods

A total of 27 diseased coronary artery samples (10–20 mm length) were resected from 7 randomly selected cadavers. OCT imaging was performed for the samples. Then, arterial samples were fixed in 10% formalin for ≥48 hours, decalcified and processed for standard paraffin embedding. Sections 5μm thick were sliced at the ink-marked imaging sites and stained with hematoxylin and eosin, and Masson's Trichrome. An independent pathologist blinded to the OCT results diagnosed all of the plaques. Subsequently, the OCT images were interpreted by an observer blinded to the histological results. In the OCT assessment, CCs were defined as thin, linear regions of high-signal intensity within a plaque.

Results

We obtained 27 pairs of OCT/ histopathology. CCs were diagnosed by histology in 10 (37%) of the 27 pairs. The sensitivity and specificity of OCT for detecting CCs were 60% and 94%, respectively.

Conclusion

OCT has a high specificity but modest sensitivity for detection of CCs in comparison with histopathology. CCs diagnosed with OCT would help the identification of advanced atherosclerotic plaques.

Acknowledgement/Funding

JSPS KAKENHI 17K09557

2421Immunosuppressive therapy and prognosis in biopsy-proven fulminant lymphocytic myocarditis requiring veno-arterial extracorporeal membranous oxygenation support

Background

Fulminant myocarditis is one of the fatal diseases for which effective management has not yet been established. Immunosuppressive therapy (IST) using corticosteroid has been actively applied to giant cell or eosinophilic myocarditis, there is no consensus on the efficacy of lymphocytic myocarditis, which is suspected of involving viral infection. Actually, IST for lymphocytic myocarditis is not recommended in the European Society of Cardiology guidelines, but in the Japanese Circulation Society guidelines, it is approved for use in refractory cases in the absence of curative therapy for myocarditis established.

Purpose

The purpose of this study was to explore the potential efficacy of immunosuppressive therapy on acute phase in fulminant lymphocytic myocarditis (FLM) requiring veno-arterial extracorporeal membranous oxygenation (VA-ECMO) support.

Method

We conducted CHANGE-PUMP study that was retrospectively enrolled 99 patients with fulminant myocarditis required VA-ECMO support in the Tokai area (central part of Japan) for the past 20 years. Lymphocytic myocarditis was defined by pathological category. Patients were divided into two groups depending on whether IST using corticosteroid was performed in the clinical course. Results: Sixty-six patients were pathologically diagnosed as fulminant myocarditis by endomyocardial biopsy, of which only 49 patients were FLM. IST were indicated in 8 (16%) out of 49 patients of FLM (IST group; n=8, non-IST group; n=41). Kaplan-Meier survival analysis showed a lower survival rate in the IST group than in the non-IST group (p=0.073). However, in all cases, based on our guidelines, IST was initiated after becoming refractory to MCS treatment.

Immunosupressive therapy and prognosis

Conclusion

In the retrospective analysis, biopsy-proven FLM patients with IST required VA-ECMO support had low survival rates. However, the timing of IST introduction was late and concerned. In the present era when advanced mechanical support appears and the survival rate of fulminant myocarditis is expected to improve, a multicenter prospective study is needed to establish an indication of IST in the acute phase of fulminant myocarditis.

P4470Identification of four genes as novel susceptibility loci for early-onset type 2 diabetes mellitus, metabolic syndrome, or hyperuricemia in Japanese

Background

Given that early-onset type 2 diabetes mellitus (T2DM), metabolic syndrome, and hyperuricemia have been shown to have strong genetic components, statistical power of a genetic association study may be increased by focusing on early-onset subjects with these conditions. Although genome-wide association studies have identified various genes and loci significantly associated with T2DM, metabolic syndrome, and hyperuricemia, genetic variants that contribute to predisposition to these conditions in Japanese individuals remain to be identified definitively.

Purpose

The purpose of the study was to identify genetic variants that confer susceptibility to early-onset T2DM, metabolic syndrome, or hyperuricemia in Japanese. We have now performed exome-wide association studies (EWASs) for early-onset subjects with T2DM, metabolic syndrome, or hyperuricemia and corresponding controls.

Methods

A total of 8102 individuals aged ≤65 years was enrolled in the study. The EWAS for T2DM was performed with 7407 subjects (1696 cases, 5711 controls), that for metabolic syndrome with 4215 subjects (2296 cases, 1919 controls), and that for hyperuricemia with 7919 subjects (1365 cases, 6554 controls). Single nucleotide polymorphisms (SNPs) were genotyped with Illumina Human Exome-12 DNA Analysis BeadChip or Infinium Exome-24 BeadChip arrays. The relation of allele frequencies for 31,210, 31,521, or 31,142 SNPs that passed quality control to T2DM, metabolic syndrome, or hyperuricemia, respectively, was examined with Fisher's exact test. To compensate for multiple comparisons of genotypes with T2DM, metabolic syndrome, or hyperuricemia, we applied Bonferroni's correction for statistical significance of association.

Results

The EWAS of allele frequencies revealed that four, six, or nine SNPs were significantly associated with T2DM (P<1.60 × 10–6), metabolic syndrome (P<1.59 × 10–6), or hyperuricemia (P<1.61 × 10–6), respectively. Multivariable logistic regression analysis with adjustment for age and sex revealed that three, six, or nine SNPs were significantly related to T2DM (P<0.0031), metabolic syndrome (P<0.0021), or hyperuricemia (P<0.0014). After examination of the association of identified SNPs to T2DM-, metabolic syndrome-, or hyperuricemia-related traits, linkage disequilibrium of the SNPs, and results of previous genome-wide association studies, we have newly identified ZNF860 and OR4F6 as susceptibility loci for T2DM, OR52E4 and OR4F6 for metabolic syndrome, and HERPUD2 for hyperuricemia.

Conclusion

Given that OR4F6 was significantly associated with both T2DM and metabolic syndrome, we thus newly identified four genes (ZNF860, OR4F6, OR52E4, HERPUD2) that confer susceptibility to early-onset T2DM, metabolic syndrome, or hyperuricemia. Determination of genotypes for the SNPs in these genes may prove informative for assessment of the genetic risk for T2DM, metabolic syndrome, or hyperuricemia in Japanese.

P5417Splenic volume changes as a hemodynamic parameter in advanced heart failure with left ventricular assist device

Background

The spleen has been recognized as an important organ to reserve 20–30% of the total blood volume. Generally, splenomegaly has been thought to be related to congestion. However, in the setting of hypovolemic shock or hypoxemia, it has been reported that spleen contracted and splenic volume decreased. On the other hand, in advanced heart failure (HF), the hemodynamics is characterized by both low cardiac output (LO) and systemic congestion, and patients sometimes need support of left ventricular assist device (LVAD). However, it remains unclear about the association between spleen size and hemodynamic parameters in patients with LO who need LVAD support.

Purpose

The purpose of this study was to investigate the relationship between spleen size and hemodynamic parameters in advanced HF before and after LVAD implantation.

Methods

We enrolled 12 advanced HF patients with LVAD (11 males, 45±10 years). All patients underwent blood test, echocardiography, right heart catheterization, and computed tomography (CT) before and after LVAD implantation. Spleen size was measured by CT volumetry. We excluded patients with splenic infarction, or any infections, or mean right atrial pressure (RAP) <5mmHg because of a possibility of hypovolemic status. LO was defined as CI less than 2.2L/min/m2.

Results

At pre- and post-LVAD implantation, cardiac output, cardiac index (CI), mean RAP, and mean pulmonary capillary wedge pressure were 3.1±0.6 vs. 4.9±0.9L/min, p=0.002; 1.7±0.3 vs. 2.8±0.3L/min/m2, p=0.002; 14±5 vs. 9±3mmHg, p=0.059; and 30±7 vs. 10±3mmHg, p=0.002, respectively. The serum brain natriuretic peptide level had significantly decreased (1101 [517–1446] vs 74 [35–216] pg/mL, p=0.002). In all patients, CI had increased to over 2.2L/min/m2. The splenic volume significantly increased from pre- to post-LVAD implantation (172±48 vs. 233±78mL, p=0.002) (Figure). Furthermore, all patients were divided into two groups; elevated RAP group (n=4) and non-elevated RAP group (n=8) after LVAD support. In elevated RAP group, there were no significant changes in the spleen size between pre- and post-LVAD implantation (167±45 vs. 223±111mL, p=0.068). On the other hand, in non-elevated RAP group, the spleen volume had significantly increased from pre- to post-LVAD support (172±53 vs. 231±62mL, p=0.011). In addition, there was one patient whose hemodynamic state had changed to LO again because of LVAD failure due to pump thrombosis. In this case, the splenic volume was 212mL before LVAD implantation with LO, and increased to 418mL after LVAD implantation with non-LO, although decreased to 227mL after LVAD pump failure with LO again.

Splenic volume changes

Conclusions

The spleen may change its size in order to keep cardiac output by regulating cardiac preload depending on the systemic perfusion in advanced HF with LVAD.

Acknowledgement/Funding

None

Investigations on the Genus Rhizoecus (Hemiptera: Rhizoecidae) with Description of Two New Species from South America

Neotropical species of the scale insect genus Rhizoecus Künckel d'Herculais (Hemiptera: Coccomorpha: Rhizoecidae) found in soil sample material of the Hungarian Natural History Museum were studied. Two new Rhizoecus species, Rhizoecus kontschani Kaydan and Konczné Benedicty sp. n., and Rhizoecus granaradewillinkae Kaydan and Szita sp. n., are described and illustrated based on the adult females. Also, the adult females of Rhizoecus keysensis Hambleton and Rhizoecus pseudocacticans Hambleton are illustrated. An identification key and new additional locality records for the currently known Rhizoecus species are provided.

P1581Early blood pressure reduction by intravenous vasodilators associates with acute kidney injury in patients with hypertensive acute decompensated heart failure

Background

In patients with hypertensive acute decompensated heart failure (ADHF), intravenous vasodilators are commonly used. However, little is known about optimal use in blood pressure (BP) management to avoid acute kidney injury (AKI).

Purpose

To investigate the association between systolic BP (SBP) changes in first 6 h and incidence of AKI within 48 h in patients with hypertensive ADHF.

Methods

Post-hoc analysis was performed on a prospectively enrolled cohort. We investigated 245 patients with ADHF and SBP >140 mmHg on arrival (mean age, 76 years; 40% female). We defined “SBP-fall” as maximum percent reduction in SBP 6h after intravenous treatment. AKI was defined as serum creatinine (SCr) ≥0.3 mg/dL, or urine output <0.5 mL/kg/h at 48 h.

Results

Mean SBP, SBP-fall and SCr level at arrival were 180 mmHg, 29.4%, and 1.21 mg/dL, respectively. Sixty-six patients experienced AKI. There were no significant differences in age, NYHA functional class, SBP and SCr at admission between AKI and Non-AKI group. AKI group had the greater SBP-fall compared with Non-AKI (36.7%versus 27.2%, p≤0.0001). Logistic regression analyses revealed that SBP-fall had an independent predictor of AKI (Table). In addition, SBP-fall had positive association with the number of concomitant used intravenous vasodilators in first 6 h (Figure).

Logistic regression analyses for AKI Univariate Multivariate AUC OR 95% CI P OR 95% CI P Ages, years, per 10 years 1.04 0.82–1.33 0.17 0.75 SBP at arrival, per 10 mmHg 1.01 0.93–1.11 0.77 SBP-fall, per 10% 1.49 1.22–1.81 <0.001 1.54 1.24–1.91 <0.001 HR, per 10 beat/min 1.12 1.00–1.25 0.049 1.07 0.95–1.21 0.28 COPD 2.95 1.06–8.21 0.04 3.06 0.99–9.43 0.054 SCr, per 1 mg/dL 1.40 0.83–2.37 0.21 Furosemide i.v. 1.12 0.42–2.95 0.82 Carperitide 3.22 1.69–6.13 0.0002 4.39 2.16–8.93 <0.001 NTG/ISDN i.v. 0.97 0.54–1.74 0.92 CCB i.v. 1.86 0.76–4.53 0.18 OR, odds ratio; CI, confidence interval; AUC, area under the curve; SBP, systolic blood pressure; COPD, chronic obstructive pulmonary disease; SCr, serum creatinine; i.v., intravenous; NTG, nitroglycerin; ISDN, isosorbide dinitrate; CCB, calcium channel blocker.

SBP-fall odds ration for AKI

Conclusion

In the first 6h of management for hypertensive ADHF patients, aggressive SBP reduction by the combination use of vasodilator agents predicted the incidence of AKI.

Excessive Oxidative Stress in the Synergistic Effects of Shikonin on the Hyperthermia-Induced Apoptosis

BACKGROUND

Hyperthermia (HT) has been used widely for cancer therapy, and the development of modern devices has made it more efficient. Shikonin (SHK) is a natural naphthoquinone derivative from a Chinese herb. Although the anticancer properties of SHK are evident, the underlying molecular mechanisms are not fully understood.

OBJECTIVE

In this study, the effects of combining low doses of SHK with mild HT were investigated in the U937 cell line.

METHODS

The cells were subjected to HT at 44°C for 10 min with or without SHK pretreatment, and parameters reflecting apoptosis, ROS generation and intracellular calcium elevation were evaluated by using DNA fragmentation, flow cytometry, and western blot analyses.

RESULTS

SHK 0.5 µM significantly enhanced HT-induced apoptosis as indicated by DNA fragmentation and caspase-3 activation with increased generation of ROS and elevation of intracellular calcium. The combined treatment also synergistically activated proapoptotic proteins and inactivated anti-apoptotic proteins. Furthermore, the phosphorylation of JNK and PKC- δ and the dephosphorylation of ERK and AKT were the upstream effects that may have compounded the induction of apoptosis. The modulatory effects of HT and SHK were abrogated with the employment of NAC and JNK-IN-8 by inactivating the MAPK pathway and cleavage of caspase-3. Intracellular calcium was also elevated and was found to be responsible for the induction of cell death evident by the DNA fragmentation with or without the employment of BAPTA-AM.

CONCLUSION

Conclusively, this study provides persuasive evidence that SHK in combination with HT is a propitious therapeutic way for augmentation of apoptosis and hence suggest a novel strategy for treating cancers.

Efficacy of dimethyl fumarate in Japanese multiple sclerosis patients: interim analysis of randomized, double-blind APEX study and its open-label extension

Background

Current data for the use of dimethyl fumarate (DMF) in Japanese patients with relapsing-remitting multiple sclerosis (RRMS) is limited.

Objectives

To assess the efficacy of DMF in Japanese patients with RRMS.

Methods

The phase 3, multinational APEX study (ClinicalTrials.gov identifier: NCT01838668) consisted of two parts: a 24-week double-blind part where subjects were randomized to receive DMF 240 mg or placebo twice daily in East Asian and Eastern European countries, and an open-label extension part where all subjects received DMF. The primary endpoint was the total number of new gadolinium-enhancing lesions in Weeks 12-24. In this interim analysis, we report efficacy data in the Japanese subgroup (DMF n = 56; placebo n = 58) over 72 weeks, including an extension phase.

Results

DMF reduced the total number of new gadolinium-enhancing lesions in Weeks 12-24 by 85% versus placebo (p < 0.0001). At Week 24, the annualized relapse rate was also reduced by 48% with DMF, versus placebo. DMF reduced the probability of relapse from Week 8 and was sustained. The number of gadolinium-enhancing lesions was maintained through 72 weeks.

Conclusions

DMF demonstrated sustained efficacy in this Japanese subgroup. The results were consistent with those observed in studies of DMF enrolling primarily Caucasian patients.

Observation of Light-by-Light Scattering in Ultraperipheral Pb+Pb Collisions with the ATLAS Detector

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.

Comparison of Fragmentation Functions for Jets Dominated by Light Quarks and Gluons from pp and Pb+Pb Collisions in ATLAS

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.

Preferences for health information in middle-aged Japanese workers based on health literacy levels: a descriptive study

OBJECTIVES

To describe the health information preferences in middle-aged Japanese workers based on health literacy (HL) levels and presence of medications.

STUDY DESIGN

A cross-sectional study.

METHODS

We performed a web-based questionnaire survey with Japanese workers aged below 60 years. HL was assessed using the total score of communicative skills (five items) and critical skills (four items) from the 14-item Health Literacy Scale. Regarding their health information preferences, participants were asked about the health information they wanted (four items), could easily understand (six items), or easily use (two items) and answered on a 4-point scale (strongly agree/agree/disagree/strongly disagree). The percentages of the affirmative responses (strongly agree or agree) were compared among tertiles based on the HL score.

RESULTS

We obtained data from a total of 3387 volunteers, of whom 510 participants were on either antihypertensive, lipid-lowering, or antidiabetic drugs. Compared with the high HL and middle HL groups, low HL had fewer affirmative responses to most health information items. Health information items received 70% of affirmative responses even in the low HL level. They were visually shown by figures or pictures, highlighted by colors for important points, could be read in 1-2 min, and were accessed on the Internet, regardless of the presence of medications. Additionally, the explanation for mechanisms of medications or lifestyle to prevent or improve diseases showed high affinity in all HL levels, only for those on medications.

CONCLUSIONS

This result generates a hypothesis that low HL individuals have a low interest in health information. Our data showed several possible forms of health information with high affinity based on HL levels that would help plan future population approaches.

Combination of Searches for Invisible Higgs Boson Decays with the ATLAS Experiment

Dark matter particles, if sufficiently light, may be produced in decays of the Higgs boson. This Letter presents a statistical combination of searches for H→invisible decays where H is produced according to the standard model via vector boson fusion, Z(ℓℓ)H, and W/Z(had)H, all performed with the ATLAS detector using 36.1  fb^{-1} of pp collisions at a center-of-mass energy of sqrt[s]=13  TeV at the LHC. In combination with the results at sqrt[s]=7 and 8 TeV, an exclusion limit on the H→invisible branching ratio of 0.26(0.17_{-0.05}^{+0.07}) at 95% confidence level is observed (expected).

Search for the Production of a Long-Lived Neutral Particle Decaying within the ATLAS Hadronic Calorimeter in Association with a Z Boson from pp Collisions at sqrt[s]=13 TeV

This Letter presents a search for the production of a long-lived neutral particle (Z_{d}) decaying within the ATLAS hadronic calorimeter, in association with a standard model (SM) Z boson produced via an intermediate scalar boson, where Z→ℓ^{+}ℓ^{-} (ℓ=e, μ). The data used were collected by the ATLAS detector during 2015 and 2016 pp collisions with a center-of-mass energy of sqrt[s]=13  TeV at the Large Hadron Collider and correspond to an integrated luminosity of 36.1±0.8  fb^{-1}. No significant excess of events is observed above the expected background. Limits on the production cross section of the scalar boson times its decay branching fraction into the long-lived neutral particle are derived as a function of the mass of the intermediate scalar boson, the mass of the long-lived neutral particle, and its cτ from a few centimeters to one hundred meters. In the case that the intermediate scalar boson is the SM Higgs boson, its decay branching fraction to a long-lived neutral particle with a cτ approximately between 0.1 and 7 m is excluded with a 95% confidence level up to 10% for m_{Z_{d}} between 5 and 15 GeV.

Search for doubly charged scalar bosons decaying into same-sign W boson pairs with the ATLAS detector

A search for doubly charged scalar bosons decaying into W boson pairs is presented. It uses a data sample from proton-proton collisions corresponding to an integrated luminosity of 36.1 fb - 1 collected by the ATLAS detector at the LHC at a centre-of-mass energy of 13 TeV in 2015 and 2016. This search is guided by a model that includes an extension of the Higgs sector through a scalar triplet, leading to a rich phenomenology that includes doubly charged scalar bosons H ± ± . Those bosons are produced in pairs in proton-proton collisions and decay predominantly into electroweak gauge bosons H ± ± → W ± W ± . Experimental signatures with several leptons, missing transverse energy and jets are explored. No significant deviations from the Standard Model predictions are found. The parameter space of the benchmark model is excluded at 95% confidence level for H ± ± bosons with masses between 200 and 220 GeV.

Erratum to: Measurement of the W boson polarisation in t t ¯ events from pp collisions at s = 8 TeV in the lepton + jets channel with ATLAS

[This corrects the article DOI: 10.1140/epjc/s10052-017-4819-4.].

A rare case of fetal extensive intracranial hemorrhage and whole-cerebral hypoplasia due to latent maternal vitamin K deficiency

We present here a late preterm infant with extensive brain lesions resulting from vitamin K deficiency. A female infant was born after 35 weeks of gestation by emergent cesarean section because of non-reassuring fetal status. Her mother had severe eating disorder and recurrent vomiting since early pregnancy. She was immediately intubated and ventilated because she was extremely pale, hypotonic, and non-reactive. Cerebral magnetic resonance imaging immediately after birth showed intraparenchymal hemorrhage in the left frontal lobe and cerebellum, marked cerebral edema, and cerebellar hypoplasia. Coagulation studies of the infant showed hepaplastin test <5%, prolonged PT and APTT, and a marked elevation of protein induced by vitamin K absence or antagonist-II. This case highlighted a potential risk of intracranial bleeding due to maternal vitamin K deficiency and difficulty in its prediction before delivery. Vitamin K supplementation to high risk mothers might be indispensable for preventing severe fetal vitamin K deficiency. Even when coagulation studies in mothers is normal, it is imperative to provide vitamin K supplementation for total protection.

Search for Higgs boson pair production in the γ γ W W ∗ channel using pp collision data recorded at s = 13 TeV with the ATLAS detector

Searches for non-resonant and resonant Higgs boson pair production are performed in the γ γ W W ∗ channel with the final state of γ γ ℓ ν j j using 36.1  fb - 1 of proton-proton collision data recorded at a centre-of-mass energy ofs = 13 TeV by the ATLAS detector at the Large Hadron Collider. No significant deviation from the Standard Model prediction is observed. A 95% confidence-level observed upper limit of 7.7 pb is set on the cross section for non-resonant production, while the expected limit is 5.4 pb. A search for a narrow-width resonance X decaying to a pair of Standard Model Higgs bosons HH is performed with the same set of data, and the observed upper limits on σ ( p p → X ) × B ( X → H H ) range between 40.0 and 6.1 pb for masses of the resonance between 260 and 500 GeV, while the expected limits range between 17.6 and 4.4 pb. When deriving the limits above, the Standard Model branching ratios of the H → γ γ and H → W W ∗ are assumed.

Measurement of the azimuthal anisotropy of charged particles produced in s NN = 5.02 TeV Pb+Pb collisions with the ATLAS detector

Measurements of the azimuthal anisotropy in lead-lead collisions ats NN = 5.02 TeV are presented using a data sample corresponding to 0.49nb - 1 integrated luminosity collected by the ATLAS experiment at the LHC in 2015. The recorded minimum-bias sample is enhanced by triggers for "ultra-central" collisions, providing an opportunity to perform detailed study of flow harmonics in the regime where the initial state is dominated by fluctuations. The anisotropy of the charged-particle azimuthal angle distributions is characterized by the Fourier coefficients, v 2 - v 7 , which are measured using the two-particle correlation, scalar-product and event-plane methods. The goal of the paper is to provide measurements of the differential as well as integrated flow harmonics v n over wide ranges of the transverse momentum, 0.5  < p T <  60 GeV, the pseudorapidity, | η | <  2.5, and the collision centrality 0-80%. Results from different methods are compared and discussed in the context of previous and recent measurements in Pb+Pb collisions ats NN = 2.76  TeV and 5.02  TeV . In particular, the shape of the p T dependence of elliptic or triangular flow harmonics is observed to be very similar at different centralities after scaling the v n and p T values by constant factors over the centrality interval 0-60% and the p T range 0.5  < p T <  5 GeV.

Search for electroweak production of supersymmetric particles in final states with two or three leptons at s = 13 TeV with the ATLAS detector

A search for the electroweak production of charginos, neutralinos and sleptons decaying into final states involving two or three electrons or muons is presented. The analysis is based on 36.1 fb- 1 ofs = 13  TeV proton-proton collisions recorded by the ATLAS detector at the Large Hadron Collider. Several scenarios based on simplified models are considered. These include the associated production of the next-to-lightest neutralino and the lightest chargino, followed by their decays into final states with leptons and the lightest neutralino via either sleptons or Standard Model gauge bosons; direct production of chargino pairs, which in turn decay into leptons and the lightest neutralino via intermediate sleptons; and slepton pair production, where each slepton decays directly into the lightest neutralino and a lepton. No significant deviations from the Standard Model expectation are observed and stringent limits at 95% confidence level are placed on the masses of relevant supersymmetric particles in each of these scenarios. For a massless lightest neutralino, masses up to 580 GeV are excluded for the associated production of the next-to-lightest neutralino and the lightest chargino, assuming gauge-boson mediated decays, whereas for slepton-pair production masses up to 500 GeV are excluded assuming three generations of mass-degenerate sleptons.

Operation and performance of the ATLAS Tile Calorimeter in Run 1

The Tile Calorimeter is the hadron calorimeter covering the central region of the ATLAS experiment at the Large Hadron Collider. Approximately 10,000 photomultipliers collect light from scintillating tiles acting as the active material sandwiched between slabs of steel absorber. This paper gives an overview of the calorimeter's performance during the years 2008-2012 using cosmic-ray muon events and proton-proton collision data at centre-of-mass energies of 7 and 8 TeV with a total integrated luminosity of nearly 30 fb - 1 . The signal reconstruction methods, calibration systems as well as the detector operation status are presented. The energy and time calibration methods performed excellently, resulting in good stability of the calorimeter response under varying conditions during the LHC Run 1. Finally, the Tile Calorimeter response to isolated muons and hadrons as well as to jets from proton-proton collisions is presented. The results demonstrate excellent performance in accord with specifications mentioned in the Technical Design Report.

Combination of the Searches for Pair-Produced Vectorlike Partners of the Third-Generation Quarks at sqrt[s]=13 TeV with the ATLAS Detector

A combination of the searches for pair-produced vectorlike partners of the top and bottom quarks in various decay channels (T→Zt/Wb/Ht, B→Zb/Wt/Hb) is performed using 36.1  fb^{-1} of pp collision data at sqrt[s]=13  TeV with the ATLAS detector at the Large Hadron Collider. The observed data are found to be in good agreement with the standard model background prediction in all individual searches. Therefore, combined 95% confidence-level upper limits are set on the production cross section for a range of vectorlike quark scenarios, significantly improving upon the reach of the individual searches. Model-independent limits are set assuming the vectorlike quarks decay to standard model particles. A singlet T is excluded for masses below 1.31 TeV and a singlet B is excluded for masses below 1.22 TeV. Assuming a weak isospin (T,B) doublet and |V_{Tb}|≪|V_{tB}|, T and B masses below 1.37 TeV are excluded.

Observation of Centrality-Dependent Acoplanarity for Muon Pairs Produced via Two-Photon Scattering in Pb+Pb Collisions at sqrt[s_{NN}]=5.02 TeV with the ATLAS Detector

This Letter presents a measurement of γγ→μ^{+}μ^{-} production in Pb+Pb collisions recorded by the ATLAS detector at the Large Hadron Collider at sqrt[s_{NN}]=5.02  TeV with an integrated luminosity of 0.49  nb^{-1}. The azimuthal angle and transverse momentum correlations between the muons are measured as a function of collision centrality. The muon pairs are produced from γγ through the interaction of the large electromagnetic fields of the nuclei. The contribution from background sources of muon pairs is removed using a template fit method. In peripheral collisions, the muons exhibit a strong back-to-back correlation consistent with previous measurements of muon pair production in ultraperipheral collisions. The angular correlations are observed to broaden significantly in central collisions. The modifications are qualitatively consistent with rescattering of the muons while passing through the hot matter produced in the collision.

Search for Resonant and Nonresonant Higgs Boson Pair Production in the bb[over ¯]τ^{+}τ^{-} Decay Channel in pp Collisions at sqrt[s]=13 TeV with the ATLAS Detector

A search for resonant and nonresonant pair production of Higgs bosons in the bb[over ¯]τ^{+}τ^{-} final state is presented. The search uses 36.1  fb^{-1} of pp collision data with sqrt[s]=13  TeV recorded by the ATLAS experiment at the LHC in 2015 and 2016. Decays of the τ-lepton pairs with at least one τ lepton decaying to final states with hadrons and a neutrino are considered. No significant excess above the expected background is observed in the data. The cross-section times branching ratio for nonresonant Higgs boson pair production is constrained to be less than 30.9 fb, 12.7 times the standard model expectation, at 95% confidence level. The data are also analyzed to probe resonant Higgs boson pair production, constraining a model with an extended Higgs sector based on two doublets and a Randall-Sundrum bulk graviton model. Upper limits are placed on the resonant Higgs boson pair production cross-section times branching ratio, excluding resonances X in the mass range 305  GeV<m_{X}<402  GeV in the simplified hMSSM minimal supersymmetric model for tanβ=2 and excluding bulk Randall-Sundrum gravitons G_{KK} in the mass range 325  GeV<m_{G_{KK}}<885  GeV for k/M[over ¯]_{Pl}=1.

Performance of missing transverse momentum reconstruction with the ATLAS detector using proton-proton collisions at s = 13 TeV

The performance of the missing transverse momentum ( E T miss ) reconstruction with the ATLAS detector is evaluated using data collected in proton-proton collisions at the LHC at a centre-of-mass energy of 13 TeV in 2015. To reconstruct E T miss , fully calibrated electrons, muons, photons, hadronically decaying τ -leptons , and jets reconstructed from calorimeter energy deposits and charged-particle tracks are used. These are combined with the soft hadronic activity measured by reconstructed charged-particle tracks not associated with the hard objects. Possible double counting of contributions from reconstructed charged-particle tracks from the inner detector, energy deposits in the calorimeter, and reconstructed muons from the muon spectrometer is avoided by applying a signal ambiguity resolution procedure which rejects already used signals when combining the various E T miss contributions. The individual terms as well as the overall reconstructed E T miss are evaluated with various performance metrics for scale (linearity), resolution, and sensitivity to the data-taking conditions. The method developed to determine the systematic uncertainties of the E T miss scale and resolution is discussed. Results are shown based on the full 2015 data sample corresponding to an integrated luminosity of 3.2 fb - 1 .

Measurement of colour flow using jet-pull observables in t t ¯ events with the ATLAS experiment at s = 13 TeV

Previous studies have shown that weighted angular moments derived from jet constituents encode the colour connections between partons that seed the jets. This paper presents measurements of two such distributions, the jet-pull angle and jet-pull magnitude, both of which are derived from the jet-pull angular moment. The measurement is performed in t t ¯ events with one leptonically decaying W boson and one hadronically decaying W boson, using 36.1 fb - 1 of pp collision data recorded by the ATLAS detector ats = 13 TeV delivered by the Large Hadron Collider. The observables are measured for two dijet systems, corresponding to the colour-connected daughters of the W boson and the two b-jets from the top-quark decays, which are not expected to be colour connected. To allow the comparison of the measured distributions to colour model predictions, the measured distributions are unfolded to particle level, after correcting for experimental effects introduced by the detector. While good agreement can be found for some combinations of predictions and observables, none of the predictions describes the data well across all observables.

Probing the Quantum Interference between Singly and Doubly Resonant Top-Quark Production in pp Collisions at sqrt[s]=13 TeV with the ATLAS Detector

This Letter presents a normalized differential cross-section measurement in a fiducial phase-space region where interference effects between top-quark pair production and associated production of a single top quark with a W boson and a b-quark are significant. Events with exactly two leptons (ee, μμ, or eμ) and two b-tagged jets that satisfy a multiparticle invariant mass requirement are selected from 36.1  fb^{-1} of proton-proton collision data taken at sqrt[s]=13  TeV with the ATLAS detector at the LHC in 2015 and 2016. The results are compared with predictions from simulations using various strategies for the interference. The standard prescriptions for interference modeling are significantly different from each other but are within 2σ of the data. State-of-the-art predictions that naturally incorporate interference effects provide the best description of the data in the measured region of phase space most sensitive to these effects. These results provide an important constraint on interference models and will guide future model development and tuning.