Measurement of electroweak production of a W boson in association with two jets in proton–proton collisions at √s=13Te

A measurement is presented of electroweak (EW) production of a W boson in association with two jets in proton–proton collisions at s=13Te. The data sample was recorded by the CMS Collaboration at the LHC and corresponds to an integrated luminosity of 35.9fb-1. The measurement is performed for the ℓνjj final state (with ℓν indicating a lepton–neutrino pair, and j representing the quarks produced in the hard interaction) in a kinematic region defined by invariant mass mjj>120Ge and transverse momenta pTj>25Ge. The cross section of the process is measured in the electron and muon channels yielding σEW(Wjj)=6.23±0.12(stat)±0.61(syst)pb per channel, in agreement with leading-order standard model predictions. The additional hadronic activity of events in a signal-enriched region is studied, and the measurements are compared with predictions. The final state is also used to perform a search for anomalous trilinear gauge couplings. Limits on anomalous trilinear gauge couplings associated with dimension-six operators are given in the framework of an effective field theory. The corresponding 95% confidence level intervals are -2.3<cWWW/Λ2<2.5Te-2, -8.8<cW/Λ2<16Te-2, and -45<cB/Λ2<46Te-2. These results are combined with the CMS EW Zjj analysis, yielding the constraint on the cW W W coupling: -1.8<cWWW/Λ2<2.0Te-2

Search for supersymmetry in electroweak production with photons and large missing transverse energy in pp collisions at root s=8TeV

Results are reported from a search for supersymmetry with gauge-mediated supersymmetry breaking in electroweak production. Final states with photons and large missing transverse energy (E-T(miss)) were examined. The data sample was collected in pp collisions at root s = 8TeV with the CMS detector at the LHC and corresponds to 7.4fb(-1). The analysis focuses on scenarios in which the lightest neutralino has bino- or wino-like components, resulting in decays to photons and gravitinos, where the gravitinos escape undetected. The data were obtained using a specially designed trigger with dedicated low thresholds, providing good sensitivity to signatures with photons, E-T(miss), and low hadronic energy. No excess of events over the standard model expectation is observed. The results are interpreted using the model of general gauge mediation. With the wino mass fixed at 10GeV above that of the bino, wino masses below 710GeV are excluded at 95% confidence level. Constraints are also set in the context of two simplified models, for which the analysis sets the lowest cross section limits on the electroweak production of supersymmetric particles. (C) 2016 The Author. Published by Elsevier B.V. This is an open access article under the CC BY license

Search for MSSM Higgs bosons decaying to μ+μ− in proton-proton collisions at s=13TeV

A search is performed for neutral non-standard-model Higgs bosons decaying to two muons in the context of the minimal supersymmetric standard model (MSSM). Proton-proton collision data recorded by the CMS experiment at the CERN Large Hadron Collider at a center-of-mass energy of 13TeVwere used, corresponding to an integrated luminosity of 35.9fb-1. The search is sensitive to neutral Higgs bosons produced via the gluon fusion process or in association with a bbquark pair. No significant deviations from the standard model expectation are observed. Upper limits at 95% confidence level are set in the context of the mmod+hand phenomenological MSSM scenarios on the parameter tanβas a function of the mass of the pseudoscalar Aboson, in the range from 130 to 600GeV. The results are also used to set a model-independent limit on the product of the branching fraction for the decay into a muon pair and the cross section for the production of a scalar neutral boson, either via gluon fusion, or in association with bquarks, in the mass range from 130 to 1000GeV

Measurement of quark- and gluon-like jet fractions using jet charge in PbPb and pp collisions at 5.02 TeV

The momentum-weighted sum of the electric charges of particles inside a jet, known as jet charge, is sensitive to the electric charge of the particle initiating the parton shower. This paper presents jet charge distributions in s NN $$\sqrt{s_{\mathrm{NN}}}$$ = 5.02 TeV lead-lead (PbPb) and proton-proton (pp) collisions recorded with the CMS detector at the LHC. These data correspond to integrated luminosities of 404 μb −1 and 27.4 pb −1 for PbPb and pp collisions, respectively. Leveraging the sensitivity of the jet charge to fundamental differences in the electric charges of quarks and gluons, the jet charge distributions from simulated events are used as templates to extract the quark- and gluon-like jet fractions from data. The modification of these jet fractions is examined by comparing pp and PbPb data as a function of the overlap of the colliding Pb nuclei (centrality). This measurement tests the color charge dependence of jet energy loss due to interactions with the quark-gluon plasma. No significant modification between different centrality classes and with respect to pp results is observed in the extracted quark- and gluon-like jet fractions.CMS Collaboration (ukupan broj autora: 2301

Study of Z boson production in pPb collisions at root S-NN=5.02 TeV

The production of Z bosons in pPb collisions at root S-NN = 5.02 TeV is studied by the CMS experiment via the electron and muon decay channels. The inclusive cross section is compared to pp collision predictions, and found to scale with the number of elementary nucleon-nucleon collisions. The differential cross sections as a function of the Z boson rapidity and transverse momentum are measured. Though they are found to be consistent within uncertainty with theoretical predictions both with and without nuclear effects, the forward-backward asymmetry suggests the presence of nuclear effects at large rapidities. These results provide new data for constraining nuclear parton distribution functions. (C) 2016 The Author. Published by Elsevier B.V

Measurement and QCD analysis of double-differential inclusive jet cross sections in pp collisions at root s=8 TeV and cross section ratios to 2.76 and 7 TeV

A measurement of the double-differential inclusive jet cross section as a function of the jet transverse momentum p(T) and the absolute jet rapidity |y| is presented. Data from LHC proton-proton collisions at root s = 8 TeV, corresponding to an integrated luminosity of 19.7 fb(-1), have been collected with the CMS detector. Jets are reconstructed using the anti-k(T) clustering algorithm with a size parameter of 0.7 in a phase space region covering jet p(T) from 74 GeV up to 2.5 TeV and jet absolute rapidity up to |y| = 3.0. The low-p(T) jet range between 21 and 74 GeV is also studied up to |y| = 4.7, using a dedicated data sample corresponding to an integrated luminosity of 5.6 pb(-1). The measured jet cross section is corrected for detector effects and compared with the predictions from perturbative QCD at next-to-leading order (NLO) using various sets of parton distribution functions (PDF). Cross section ratios to the corresponding measurements performed at 2.76 and 7 TeV are presented. From the measured double-differential jet cross section, the value of the strong coupling constant evaluated at the Z mass is alpha(S)(M-Z) = 0.1164(-0.0043)(+0.0060) , where the errors include the PDF, scale, nonperturbative effects and experimental uncertainties, using the CT10 NLO PDFs. Improved constraints on PDFs based on the inclusive jet cross section measurement are presented

Search for new physics in final states with two opposite-sign, same-flavor leptons, jets, and missing transverse momentum in pp collisions at TeV

A search is presented for physics beyond the standard model in final states with two opposite-sign, same-flavor leptons, jets, and missing transverse momentum. The data sample corresponds to an integrated luminosity of 2.3 fb(-1) of proton-proton collisions at TeV collected with the CMS detector at the LHC in 2015. The analysis uses the invariant mass of the lepton pair, searching for a kinematic edge or a resonant-like excess compatible with the Z boson mass. Both search modes use several event categories in order to increase the sensitivity to new physics. These categories are based on the rapidity of the leptons, the multiplicity of jets and b jets, the scalar sum of jet transverse momenta, and missing transverse momentum. The observations in all signal regions are consistent with the expectations from the standard model, and the results are interpreted in the context of simplified models of supersymmetry

Evaluation of Sentinel Node Biopsy in Oral Carcinomas

It is still a matter of debate whether sentinel node biopsy might replace neck dissection in patients with clinically negative neck lymph nodes who suffer from oral squamous cell carcinoma. In 30 patients (26 male, 4 female, average age 59.4 years) with oral squamous cell carcinoma we performed ultrasound guided punction of the lymph nodes which were lymphoscintigraphically seen together with histopatological analysis of the dissected node. Sentinel lymph node was seen in 93% cases. By use of lymphoscintigraphy sentinel node was verified in 23 patients. Ultrasound guided punction showed presence of regional disease in 10% of cases, whereas sentinel biopsy revealed 23 of the converted necks. Histopathological findings were positive in 33% of our patients. The results of this study revealed that sentinel biopsy did not reveal 27% of the patients with positive neck histopathology. In conclusion, sentinel node biopsy should be performed in selective cases as in some localizations it is easier to perform neck dissection in comparison to the sentinel node biopsy

Measurements of t(t)over-bar spin correlations and top quark polarization using dilepton final states in pp collisions at root s=8 TeV

Measurements of the top quark-antiquark (t (t) over bar) spin correlations and the top quark polarization are presented for t (t) over bar pairs produced in pp collisions at root s = 8 TeV. The data correspond to an integrated luminosity of 19.5 fb(-1) collected with the CMS detector at the LHC. The measurements are performed using events with two oppositely charged leptons (electrons or muons) and two or more jets, where at least one of the jets is identified as originating from a bottom quark. The spin correlations and polarization are measured from the angular distributions of the two selected leptons, both inclusively and differentially, with respect to the invariant mass, rapidity, and transverse momentum of the t (t) over bar system. The measurements are unfolded to the parton level and found to be in agreement with predictions of the standard model. A search for new physics in the form of anomalous top quark chromo moments is performed. No evidence of new physics is observed, and exclusion limits on the real part of the chromo-magnetic dipole moment and the imaginary part of the chromo-electric dipole moment are evaluated

Charged-particle nuclear modification factors in PbPb and pPb collisions at root s(NN)=5.02 TeV

The spectra of charged particles produced within the pseudorapidity window vertical bar eta vertical bar LT 1 at root s(NN) = 5 : 02 TeV are measured using 404 mu b(-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 LT p(T) LT 400 GeV in pp and 0 : 7 LT p(T) LT 400 GeV in PbPb collisions. The corresponding nuclear modification factor, R-AA, is measured in bins of collision centrality. The R-AA in the 5% most central collisions shows a maximal suppression by a factor of 7-8 in the p(T) region of 6-9 GeV. This dip is followed by an increase, which continues up to the highest p(T) measured, and approaches unity in the vicinity of p(T) = 200 GeV. The R-AA 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, R-pA, up to 120 GeV. For p(T) GT 20 GeV, R-pA exhibits weak momentum dependence and shows a moderate enhancement above unity