Measurements of differential production cross sections for a Z boson in association with jets in pp collisions at root s=8 TeV

Peer reviewe

Charged-particle nuclear modification factors in PbPb and pPb collisions at √=sNN=5.02 TeV

The spectra of charged particles produced within the pseudorapidity window |η| < 1 at √ sNN = 5.02 TeV are measured using 404 µb −1 of PbPb and 27.4 pb−1 of pp data collected by the CMS detector at the LHC in 2015. The spectra are presented over the transverse momentum ranges spanning 0.5 < pT < 400 GeV in pp and 0.7 < pT < 400 GeV in PbPb collisions. The corresponding nuclear modification factor, RAA, is measured in bins of collision centrality. The RAA in the 5% most central collisions shows a maximal suppression by a factor of 7–8 in the pT region of 6–9 GeV. This dip is followed by an increase, which continues up to the highest pT measured, and approaches unity in the vicinity of pT = 200 GeV. The RAA is compared to theoretical predictions and earlier experimental results at lower collision energies. The newly measured pp spectrum is combined with the pPb spectrum previously published by the CMS collaboration to construct the pPb nuclear modification factor, RpA, up to 120 GeV. For pT > 20 GeV, RpA exhibits weak momentum dependence and shows a moderate enhancement above unity

European cardiomyopathy pilot registry: EURObservational research programme of the European society of cardiology

Aims: Cardiomyopathies are a heterogeneous group of disorders associated with premature death due to ventricular arrhythmia or heart failure. The purpose of this study was to examine the characteristics of patients enrolled in the pilot phase of the EURObservational Research Programme (EORP) cardiomyopathy registry. Methods and results: Between 1 December 2012 and 30 November 2013, four cardiomyopathy phenotypes were studied: hypertrophic cardiomyopathy (HCM), dilated cardiomyopathy (DCM), arrhythmogenic right ventricular cardiomyopathy (ARVC), and restrictive cardiomyopathy (RCM). Twenty-seven centres in 12 countries participated; 1115 patients were enrolled. The commonest cardiomyopathy was HCM (n = 681), followed by DCM (n = 346), ARVC (n = 59), and RCM (n = 29); 423 patients (46.4% of those reported) had familial disease; and 56 (5.0%) had rare disease phenocopies. Median age at enrolment and diagnosis was 54 [interquartile range (IQR), 42-64] and 46 years (IQR, 32-58), respectively; fewer patients with ARVC and more with RCM were diagnosed in the upper age quartile (P, 0.0001). There was a male predominance for all cardiomyopathies except RCM (P = 0.0023). Most patients were in New York Heart Association functional class I (n = 813) at enrolment; 139 (12.5%) reported syncope, most frequently in ARVC (P = 0.0009). Five hundred and seven (45.5%) patients underwent cardiac magnetic resonance imaging, 117 (10.6%) endomyocardial biopsy, and 462 (41.4%) genetic testing with a causative mutation reported in 236 individuals (51.1%). 1026 patients (92.0%) were receiving drug therapy; 316 (28.3%) had received an implantable cardioverter defibrillator (highest proportion in ARVC, P, 0.0001). Conclusion: This pilot study shows that services for patients with cardiomyopathy are complex, requiring access to a large range of invasive and non-invasive investigations and involvement of multidisciplinary teams. Treatment regimens are equally multifaceted and show that patients are likely to need long-term follow-up in close liaison with expert centres. © The Author 2015

Measurements with silicon photomultipliers of dose-rate effects in the radiation damage of plastic scintillator tiles in the CMS hadron endcap calorimeter

Measurements are presented of the reduction of signal output due to radiation damage for two types of plastic scintillator tiles used in the hadron endcap (HE) calorimeter of the CMS detector. The tiles were exposed to particles produced in proton-proton (pp) collisions at the CERN LHC with a center-of-mass energy of 13 TeV, corresponding to a delivered luminosity of 50 fb-1. The measurements are based on readout channels of the HE that were instrumented with silicon photomultipliers, and are derived using data from several sources: A laser calibration system, a movable radioactive source, as well as hadrons and muons produced in pp collisions. Results from several irradiation campaigns using 60Co sources are also discussed. The damage is presented as a function of dose rate. Within the range of these measurements, for a fixed dose the damage increases with decreasing dose rate

Search for dark matter produced in association with heavy-flavor quark pairs in proton-proton collisions at √s=13TeV

A search is presented for an excess of events with heavy-flavor quark pairs (tt¯ and bb¯) and a large imbalance in transverse momentum in data from proton–proton collisions at a center-of-mass energy of 13TeV. The data correspond to an integrated luminosity of 2.2fb-1 collected with the CMS detector at the CERN LHC. No deviations are observed with respect to standard model predictions. The results are used in the first interpretation of dark matter production in tt¯ and bb¯ final states in a simplified model. This analysis is also the first to perform a statistical combination of searches for dark matter produced with different heavy-flavor final states. The combination provides exclusions that are stronger than those achieved with individual heavy-flavor final states. © 2017, CERN for the benefit of the CMS collaboration

Measurement of single-diffractive dijet production in proton–proton collisions at √s=8Te with the CMS and TOTEM experiments

Measurements are presented of the single-diffractive dijet cross section and the diffractive cross section as a function of the proton fractional momentum loss ξ and the four-momentum transfer squared t. Both processes pp→pX and pp→Xp, i.e. with the proton scattering to either side of the interaction point, are measured, where X includes at least two jets; the results of the two processes are averaged. The analyses are based on data collected simultaneously with the CMS and TOTEM detectors at the LHC in proton–proton collisions at s=8Te during a dedicated run with β∗=90m at low instantaneous luminosity and correspond to an integrated luminosity of 37.5nb-1. The single-diffractive dijet cross section σjjpX, in the kinematic region ξ&amp;lt; 0.1 , 0.03&amp;lt;|t|&amp;lt;1Ge2, with at least two jets with transverse momentum pT&amp;gt;40Ge, and pseudorapidity | η| &amp;lt; 4.4 , is 21.7±0.9(stat)-3.3+3.0(syst)±0.9(lumi)nb. The ratio of the single-diffractive to inclusive dijet yields, normalised per unit of ξ, is presented as a function of x, the longitudinal momentum fraction of the proton carried by the struck parton. The ratio in the kinematic region defined above, for x values in the range - 2.9 ≤ log 10x≤ - 1.6 , is R=(σjjpX/Δξ)/σjj=0.025±0.001(stat)±0.003(syst), where σjjpX and σjj are the single-diffractive and inclusive dijet cross sections, respectively. The results are compared with predictions from models of diffractive and nondiffractive interactions. Monte Carlo predictions based on the HERA diffractive parton distribution functions agree well with the data when corrected for the effect of soft rescattering between the spectator partons. © 2020, CERN for the benefit of the CMS and TOTEM collaborations