Observation of WWγ Production and Search for Hγ Production in Proton-Proton Collisions at sqrt[s]=13 TeV

The observation of WWγ production in proton-proton collisions at a center-of-mass energy of 13 TeV with an integrated luminosity of 138  fb^{-1} is presented. The observed (expected) significance is 5.6 (5.1) standard deviations. Events are selected by requiring exactly two leptons (one electron and one muon) of opposite charge, moderate missing transverse momentum, and a photon. The measured fiducial cross section for WWγ is 5.9±0.8(stat)±0.8(syst)±0.7(modeling)  fb, in agreement with the next-to-leading order quantum chromodynamics prediction. The analysis is extended with a search for the associated production of the Higgs boson and a photon, which is generated by a coupling of the Higgs boson to light quarks. The result is used to constrain the Higgs boson couplings to light quarks.

New Structures in the J/ψJ/ψ Mass Spectrum in Proton-Proton Collisions at sqrt[s]=13 TeV

A search is reported for near-threshold structures in the J/ψJ/ψ invariant mass spectrum produced in proton-proton collisions at sqrt[s]=13  TeV from data collected by the CMS experiment, corresponding to an integrated luminosity of 135  fb^{-1}. Three structures are found, and a model with quantum interference among these structures provides a good description of the data. A new structure is observed with a local significance above 5 standard deviations at a mass of 6638_{-38}^{+43}(stat)_{-31}^{+16}(syst)  MeV. Another structure with even higher significance is found at a mass of 6847_{-28}^{+44}(stat)_{-20}^{+48}(syst)  MeV, which is consistent with the X(6900) resonance reported by the LHCb experiment and confirmed by the ATLAS experiment. Evidence for another new structure, with a local significance of 4.7 standard deviations, is found at a mass of 7134_{-25}^{+48}(stat)_{-15}^{+41}(syst)  MeV. Results are also reported for a model without interference, which does not fit the data as well and shows mass shifts up to 150 MeV relative to the model with interference.

Search for Scalar Leptoquarks Produced via τ-Lepton-Quark Scattering in pp Collisions at sqrt[s]=13 TeV

The first search for scalar leptoquarks produced in τ-lepton-quark collisions is presented. It is based on a set of proton-proton collision data recorded with the CMS detector at the LHC at a center-of-mass energy of 13 TeV corresponding to an integrated luminosity of 138  fb^{-1}. The reconstructed final state consists of a jet, significant missing transverse momentum, and a τ lepton reconstructed through its hadronic or leptonic decays. Limits are set on the product of the leptoquark production cross section and branching fraction and interpreted as exclusions in the plane of the leptoquark mass and the leptoquark-τ-quark coupling strength.

Search for Inelastic Dark Matter in Events with Two Displaced Muons and Missing Transverse Momentum in Proton-Proton Collisions at sqrt[s]=13 TeV

A search for dark matter in events with a displaced nonresonant muon pair and missing transverse momentum is presented. The analysis is performed using an integrated luminosity of 138  fb^{-1} of proton-proton (pp) collision data at a center-of-mass energy of 13 TeV produced by the LHC in 2016-2018. No significant excess over the predicted backgrounds is observed. Upper limits are set on the product of the inelastic dark matter production cross section σ(pp→A^{'}→χ_{1}χ_{2}) and the decay branching fraction B(χ_{2}→χ_{1}μ^{+}μ^{-}), where A^{'} is a dark photon and χ_{1} and χ_{2} are states in the dark sector with near mass degeneracy. This is the first dedicated collider search for inelastic dark matter.

Luminosity determination using Z boson production at the CMS experiment

The measurement of Z boson production is presented as a method to determine the integrated luminosity of CMS data sets. The analysis uses proton-proton collision data, recorded by the CMS experiment at the CERN LHC in 2017 at a center-of-mass energy of 13Te V . Events with Z bosons decaying into a pair of muons are selected. The total number of Z bosons produced in a fiducial volume is determined, together with the identification efficiencies and correlations from the same data set, in small intervals of 20pb - 1 of integrated luminosity, thus facilitating the efficiency and rate measurement as a function of time and instantaneous luminosity. Using the ratio of the efficiency-corrected numbers of Z bosons, the precisely measured integrated luminosity of one data set is used to determine the luminosity of another. For the first time, a full quantitative uncertainty analysis of the use of Z  bosons for the integrated luminosity measurement is performed. The uncertainty in the extrapolation between two data sets, recorded in 2017 at low and high instantaneous luminosity, is less than 0.5%. We show that the Z boson rate measurement constitutes a precise method, complementary to traditional methods, with the potential to improve the measurement of the integrated luminosity.

Observation of the Rare Decay of the η Meson to Four Muons

A search for the rare η→μ^{+}μ^{-}μ^{+}μ^{-} double-Dalitz decay is performed using a sample of proton-proton collisions, collected by the CMS experiment at the CERN LHC with high-rate muon triggers during 2017 and 2018 and corresponding to an integrated luminosity of 101  fb^{-1}. A signal having a statistical significance well in excess of 5 standard deviations is observed. Using the η→μ^{+}μ^{-} decay as normalization, the branching fraction B(η→μ^{+}μ^{-}μ^{+}μ^{-})=[5.0±0.8(stat)±0.7(syst)±0.7(B_{2μ})]×10^{-9} is measured, where the last term is the uncertainty in the normalization channel branching fraction. This work achieves an improved precision of over 5 orders of magnitude compared to previous results, leading to the first measurement of this branching fraction, which is found to agree with theoretical predictions.

Pushing NMR sensitivity limits using dynamic nuclear polarization with closed-loop cryogenic helium sample spinning

We report a strategy to push the limits of solid-state NMR sensitivity far beyond its current state-of-the-art. The approach relies on the use of dynamic nuclear polarization and demonstrates unprecedented DNP enhancement factors for experiments performed at sample temperatures much lower than 100 K, and can translate into 6 orders of magnitude of experimental time-savings. This leap-forward was made possible thanks to the employment of cryogenic helium as the gas to power magic angle sample spinning (MAS) for dynamic nuclear polarization (DNP) enhanced NMR experiments. These experimental conditions far exceed what is currently possible and allows currently reaching sample temperatures down to 30 K while conducting experiments with improved resolution (thanks to faster spinning frequencies, up to 25 kHz) and highly polarized nuclear spins. The impressive associated gains were used to hyperpolarize the surface of an industrial catalyst as well as to hyperpolarize organic nano-assemblies (self-assembling peptides in our case), for whom structures cannot be solved using diffraction techniques. Sustainable cryogenic helium sample spinning significantly enlarges the realm and possibilities of the MAS-DNP technique and is the route to transform NMR into a versatile but also sensitive atomic-level characterization tool.

NMR in the SPINE Structural Proteomics project

This paper describes the developments, role and contributions of the NMR spectroscopy groups in the Structural Proteomics In Europe (SPINE) consortium. Focusing on the development of high-throughput (HTP) pipelines for NMR structure determinations of proteins, all aspects from sample preparation, data acquisition, data processing, data analysis to structure determination have been improved with respect to sensitivity, automation, speed, robustness and validation. Specific highlights are protonless (13)C-direct detection methods and inferential structure determinations (ISD). In addition to technological improvements, these methods have been applied to deliver over 60 NMR structures of proteins, among which are five that failed to crystallize. The inclusion of NMR spectroscopy in structural proteomics pipelines improves the success rate for protein structure determinations.

Degenerative Endometrial Changes do not Change the Functional Capacity of Immigrating Uterine Neutrophils in Mares

An endometritis model was used to investigate the influence of degenerative endometrial changes (endometrosis) on functional parameters of uterine neutrophils in the horse. Six hours after intrauterine application of recombinant human interleukin-8 (rhIL-8), the uteri of 15 mares were flushed with phosphate-buffered saline. Quantitative and qualitative flow cytometric assays were then made to determine the absolute numbers, viability, phenotype, generation of reactive oxygen species (ROS), and phagocytic activity of immigrated polymorphonuclear neutrophilic granulocytes (PMN). Recombinant hIL-8 attracted similarly high numbers of similarly viable PMN into the uteri of mares with or without degenerative endometrial changes. Compared with blood PMN, immigrated uterine neutrophils displayed significantly upregulated expression of CD11a/CD18 (LFA-1) on uterine PMN whereas major histocompatibility complex class I molecules were expressed at lower densities. The ability to phagocytose opsonized streptococci did not differ between uterine and blood PMN. However, uterine PMN displayed a higher capacity to generate ROS. On average, uterine PMN of mares with degenerative endometrial changes showed phenotypical and functional characteristics similar to those of mares with a histologically healthy endometrium. Therefore, degenerative endometrial changes per se did not reduce the functional capacity of equine uterine neutrophils in mares.

Development and comparison of in vivo and in vitro models for endometritis in cows and mares

In order to investigate pathogenic mechanisms of acute endometritis in cows and mares, we established an in vivo model in both species. Based on the results of an in vitro transmigration system, human recombinant interleukin-8 (rhIL-8; 1.25 microg per mare and 5 microg per cow in 50 ml phosphate-buffered saline) was used to attract polymorphonuclear neutrophil granulocytes (PMNs) into the uteri. Peak numbers of uterine neutrophils were attracted after 6h, in both cows and mares. On average, mares responded more sensitively than cows, with 15 times higher numbers of rhIL-8-attracted uterine neutrophils (72+/-8 x 10(7)cells). In contrast to in vitro studies, in vivo migrated neutrophils (uterine neutrophils) of both species displayed a significantly reduced MHC class I expression. Expression of the CD11a molecule was significantly enhanced on equine uterine neutrophils but downregulated on bovine cells. Compared with untreated autologous peripheral neutrophils, both uterine and in vitro migrated neutrophils showed no alteration of phagocytic capacity. The ability to generate reactive oxygen species (ROS) was significantly upregulated in bovine and equine uterine neutrophils. This was also observed after in vitro migration of equine neutrophils, whereas ROS generation by bovine neutrophils was significantly depressed. In summary, the concept of inducing endometritis directly by local application of human interleukin-8 has been reliably successful in cows and mares. The model permits the analysis of PMN migration into the uterus under defined and controlled conditions. The observed differences between cows and mares with respect to phenotypical and functional characteristics of in vivo attracted uterine cells point to species-related features of neutrophil migration. In vitro transmigrated bovine and equine cells partially differ in phenotype and function from uterine neutrophils. Therefore, the in vitro transmigration assay cannot completely represent the in vivo endometritis model described here.

Isolation and cryopreservation of functionally competent equine leucocytes

Sufficient numbers of functionally competent polymorphonuclear neutrophil granulocytes (PMN) seem to be of major importance during the course of equine endometritis. In this study, we wanted to establish a method for cryopreservation of functionally competent neutrophils for an intended local endometritis therapy in mares. The separation of leucocytes by hypotonic lysis of whole blood from clinically healthy mares was superior to the separation by dextrose sedimentation. After suspension of the cells in the cryoprotective solution [equine plasma with 5% (v/v) dimethyl sulphoxide (DMSO)], the leucocytes were frozen in liquid nitrogen. A temperature gradient with low cooling velocity (1 degree C/min between 4 and -70 degrees C) resulted in highest numbers of viable cells after thawing. Thawed PMN had a high phagocytic capacity for opsonized streptococci. Their ability to generate reactive oxygen species (ROS) after stimulation with a phorbol ester was even higher than that of freshly isolated PMN and was preserved up to 6 h after thawing. The results of this study indicate that cryopreservation of PMN may provide viable and functionally competent neutrophils for therapeutic use in mares susceptible to endometritis.

Effect of sequence length, sequence frequency, and data acquisition rate on the performance of a Hadamard transform time-of-flight mass spectrometer

Various factors influencing the performance of a Hadamard transform time-of-flight mass spectrometer (HT-TOFMS) have been investigated. Using a nitrogen corona discharge to produce an ion stream of N2+, N3+, and N4+, it is found for spectra containing only N4+ that the signal-to-noise ratio (SNR) closely approaches the value calculated from the ion background by assuming that the ion background follows a Poisson distribution. In contrast, for a more intense beam containing N2+, N3+, and N4+, the SNR is less than its theoretical value because of the appearance of discrete spikes in the mass spectrum caused by deviations in the actual modulation sequence from the ideal one. These spikes can be reduced, however, by decreasing the modulation voltage. Under these optimized conditions, the pseudo-random sequence length is varied to understand how it alters SNR, mass resolution, and scan speed. When the length of the pseudo-random sequence is doubled, the SNR increases by the square root of 2 while the time necessary to record a mass spectrum also doubles. Mass resolution can be varied between 500 and 1200 at m/z = 609 as the sequence length, modulation speed (10 MHz, 25 MHz), and acquisition rate (up to 50 MHz) are changed. Scan speeds of 6000 passes per s can be obtained using a sequence containing 4095 elements modulated at 25 MHz. The capability to tailor the HT-TOFMS to increase the scan speed and resolution with a constant 50% duty cycle makes the technique extremely appealing as a mass analyzer for measuring rapid changes in the composition of an ion stream.

Development of NMR instrumentation to achieve excitation of large bandwidths in high-resolution spectra at high field

A prototype 2.5-mm (1)H high-resolution probe for an 18.8-T (800 MHz) nuclear magnetic resonance spectrometer has been designed, together with a dedicated amplifier capable of delivering up to 1 kW of power. This probe permits a 90 degrees pulse length of 2 mus to be achieved at 300 W, corresponding to an excitation bandwidth of +/-125 kHz. Probe performances were tested on samples commonly used for this purpose as well as on protein and paramagnetic model compound samples. It is shown that this probe is useful for a wide range of applications at high magnetic field, especially in the study of systems characterized by very broad and far-shifted resonances and in experiments that require high-power radiofrequency irradiation.

Sample restriction using magnetic field gradients in high-resolution solid-state NMR

Many solid-state NMR experiments are sensitive to inhomogeneity in the radiofrequency field. We propose a method to restrict the sample volume, in magic angle spinning experiments, using a static magnetic field gradient and a selective pulse. The position of the gradient is calculated for our experimental configuration and we have simulated the effects of selective pulses to determine the excited volume. The resulting sequences are applied to a sample of sodium acetate using frequency-switched Lee-Goldburg proton-proton homonuclear dipolar decoupling. A gain of a factor of 2 on the carbon resolution is experimentally observed. Copyright 2000 Academic Press.