Search for direct pair production of supersymmetric partners to the τ lepton in proton–proton collisions at √s = 13 TeV

A search is presented for τ slepton pairs produced in proton–proton collisions at a center-of-mass energy of 13TeV. The search is carried out in events containing two τ leptons in the final state, on the assumption that each τ slepton decays primarily to a τ lepton and a neutralino. Events are considered in which each τ lepton decays to one or more hadrons and a neutrino, or in which one of the τ leptons decays instead to an electron or a muon and two neutrinos. The data, collected with the CMS detector in 2016 and 2017, correspond to an integrated luminosity of 77.2fb⁻¹. The observed data are consistent with the standard model background expectation. The results are used to set 95% confidence level upper limits on the cross section for τ slepton pair production in various models for τ slepton masses between 90 and 200GeV and neutralino masses of 1, 10, and 20GeV. In the case of purely left-handed τ slepton production and decay to a τ lepton and a neutralino with a mass of 1GeV, the strongest limit is obtained for a τ slepton mass of 125GeV at a factor of 1.14 larger than the theoretical cross section

Search for direct pair production of supersymmetric partners to the τ lepton in proton–proton collisions at s=13 TeV\sqrt{s}=13\,\text {TeV}

A search is presented for τ slepton pairs produced in proton–proton collisions at a center-of-mass energy of 13 TeV. The search is carried out in events containing two τ leptons in the final state, on the assumption that each τ slepton decays primarily to a τ lepton and a neutralino. Events are considered in which each τ lepton decays to one or more hadrons and a neutrino, or in which one of the τ leptons decays instead to an electron or a muon and two neutrinos. The data, collected with the CMS detector in 2016 and 2017, correspond to an integrated luminosity of 77.2 fb$^{-1}$. The observed data are consistent with the standard model background expectation. The results are used to set 95% confidence level upper limits on the cross section for τ slepton pair production in various models for τ slepton masses between 90 and 200 GeV and neutralino masses of 1, 10, and 20 GeV. In the case of purely left-handed τ slepton production and decay to a τ lepton and a neutralino with a mass of 1GeV, the strongest limit is obtained for a τ slepton mass of 125 GeV at a factor of 1.14 larger than the theoretical cross section

A multi-dimensional search for new heavy resonances decaying to boosted W \text{ W }{}{} W \text{ W }{}{} , W \text{ W }{}{} Z \text{ Z }{}{} , or Z \text{ Z }{}{} Z \text{ Z }{}{} boson pairs in the dijet final state at 13 TeV

A search in an all-jet final state for new massive resonances decaying to WW, WZ, or ZZ boson pairs using a novel analysis method is presented. The analysis is performed on data corresponding to an integrated luminosity of 77.3 fb$^{-1}$ recorded with the CMS experiment at the LHC at a centre-of-mass energy of 13TeV. The search is focussed on potential narrow-width resonances with masses above 1.2TeV, where the decay products of each W or Z boson are expected to be collimated into a single, large-radius jet. The signal is extracted using a three-dimensional maximum likelihood fit of the two jet masses and the dijet invariant mass, yielding an improvement in sensitivity of up to 30% relative to previous search methods. No excess is observed above the estimated standard model background. In a heavy vector tripletmodel, spin-1Z` and W` resonances with masses below 3.5 and 3.8 TeV, respectively, are excluded at 95% confidence level. In a bulk graviton model, upper limits on cross sections are set between 27 and 0.2 fb for resonance masses between 1.2 and 5.2TeV, respectively. The limits presented in this paper are the best to date in the dijet final state

Search for direct pair production of supersymmetric partners to the tau lepton in proton-proton collisions at root s=13TeV

A search is presented for t slepton pairs produced in proton-proton collisions at a center-of-mass energy of 13 TeV. The search is carried out in events containing two t leptons in the final state, on the assumption that each t slepton decays primarily to a t lepton and a neutralino. Events are considered in which each t lepton decays to one or more hadrons and a neutrino, or in which one of the t leptons decays instead to an electron or a muon and two neutrinos. The data, collected with the CMS detector in 2016 and 2017, correspond to an integrated luminosity of 77.2 fb-1. The observed data are consistent with the standard model background expectation. The results are used to set 95% confidence level upper limits on the cross section for t slepton pair production in various models for t slepton masses between 90 and 200 GeV and neutralino masses of 1, 10, and 20 GeV. In the case of purely left-handed t slepton production and decay to a t lepton and a neutralino with a mass of 1GeV, the strongest limit is obtained for a t slepton mass of 125 GeV at a factor of 1.14 larger than the theoretical cross section.Peer reviewe

Mixed higher-order anisotropic flow and nonlinear response coefficients of charged particles in PbPb collisions at S\sqrt{S}NN_{NN}=2.76 and 5.02TeV

Anisotropies in the initial energy density distribution of the quark-gluon plasma created in high energy heavy ion collisions lead to anisotropies in the azimuthal distributions of the final-state particles known as collective anisotropic flow. Fourier harmonic decomposition is used to quantify these anisotropies. The higher-order harmonics can be induced by the same order anisotropies (linear response) or by the combined influence of several lower order anisotropies (nonlinear response) in the initial state. The mixed higher-order anisotropic flow and nonlinear response coefficients of charged particles are measured as functions of transverse momentum and centrality in PbPb collisions at nucleon-nucleon center-of-mass energies $\sqrt{S}$$_{NN}$=2.76 and 5.02TeV with the CMS detector. The results are compared with viscous hydrodynamic calculations using several different initial conditions, as well as microscopic transport model calculations. None of the models provides a simultaneous description of the mixed higher-order flow harmonics and nonlinear response coefficients

Mixed higher-order anisotropic flow and nonlinear response coefficients of charged particles in PbPb collisions at root s(NN)=2.76 and 5.02 TeV

Anisotropies in the initial energy density distribution of the quark-gluon plasma created in high energy heavy ion collisions lead to anisotropies in the azimuthal distributions of the final-state particles known as collective anisotropic flow. Fourier harmonic decomposition is used to quantify these anisotropies. The higher-order harmonics can be induced by the same order anisotropies (linear response) or by the combined influence of several lower order anisotropies (nonlinear response) in the initial state. The mixed highe-rorder anisotropic flow and nonlinear response coefficients of charged particles are measured as functions of transverse momentum and centrality in PbPb collisions at nucleon-nucleon center-of-mass energies root s(NN) = 2.76 and 5.02 TeV with the CMS detector. The results are compared with viscous hydrodynamic calculations using several different initial conditions, aswell asmicroscopic transport model calculations. None of the models provides a simultaneous description of the mixed higher-order flow harmonics and nonlinear response coefficients.Peer reviewe

Search for production of four top quarks in final states with svame-sign or multiple leptons in proton-proton collisions at root s=13 TeV

The standard model (SM) production of four top quarks (tt over bar tt over ba in proton-proton collisions is studied by the CMS Collaboration. The data sample, collected during the 2016-2018 data taking of the LHC, corresponds to an integrated luminosity of 137fb-1 at a center-of-mass energy of 13TeV. The events are required to contain two same-sign charged leptons (electrons or muons) or at least three leptons, and jets. The observed and expected significances for the tt over bar tt over bar signal are respectively 2.6 and 2.7 standard deviations, and the tt over bar tt over bar cross section is measured to be 12.6-5.2+5.8fb. The results are used to constrain the Yukawa coupling of the top quark to the Higgs boson, yielding a limit of <1. 7 is the SM value of yt. They are also used to constrain the oblique parameter of the Higgs boson in an effective field theory framework, H. Limits are set on the production of a heavy scalar or pseudoscalar boson in Type-II two-Higgs-doublet and simplified dark matter models, with exclusion limits reaching 350-470GeV and 350-550GeV for scalar and pseudoscalar bosons, respectively. Upper bounds are also set on couplings of the top quark to new light particles.Peer reviewe