41.
42.
Search for a Light Charged Higgs Boson Decaying to a W Boson and a CP -Odd Higgs Boson in Final States with eμμ or μμμ in Proton-Proton Collisions at s =13 TeV
Sirunyan, A M; Tumasyan, A; Adam, W ...
Physical review letters,
07/2019, Letnik:
123, Številka:
13
Journal Article
A search for a light charged Higgs boson (H+) decaying to a W boson and a CP-odd Higgs boson (A) in final states with eμμ or μμμ is performed using data from pp collisions at s=13 TeV, recorded by ...
the CMS detector at the LHC and corresponding to an integrated luminosity of 35.9 fb-1. In this search, it is assumed that the H+ boson is produced in decays of top quarks, and the A boson decays to two oppositely charged muons. The presence of signals for H+ boson masses between 100 and 160 GeV and A boson masses between 15 and 75 GeV is investigated. No evidence for the production of the H+ boson is found. Upper limits at 95% confidence level are obtained on the combined branching fraction for the decay chain, t→bH+→bW+A→bW+μ+μ-, of 1.9×10-6 to 8.6×10-6, depending on the masses of the H+ and A bosons. These are the first limits for these decay modes of the H+ and A bosons.
več
43.
Search for W Boson Decays to Three Charged Pions
Sirunyan, A M; Tumasyan, A; Adam, W ...
Physical review letters,
07/2019, Letnik:
122, Številka:
15
Journal Article
For the first time, a search for the rare decay of the W boson to three charged pions has been performed. Proton-proton collision data recorded by the CMS experiment at a center-of-mass energy of 13 ...
TeV, corresponding to an integrated luminosity of 77.3 fb-1, have been analyzed. No significant excess is observed above the background expectation. An upper limit of 1.01×10-6 is set at 95% confidence level on the branching fraction of the W boson to three charged pions. This provides a strong motivation for theoretical calculations of this branching fraction. © 2019 CERN. for the CMS Collaboration. Published by the American Physical Society under the terms of the »https://creativecommons.org/licenses/by/4.0/» Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI. Funded by SCOAP 3 .
več
44.
Observation of Two Excited Bc+ States and Measurement of the Bc+ (2S) Mass in pp Collisions at s =13 TeV
Sirunyan, A M; Tumasyan, A; Adam, W ...
Physical review letters,
07/2019, Letnik:
122, Številka:
13
Journal Article
Signals consistent with the Bc+(2S) and Bc∗+(2S) states are observed in proton-proton collisions at s=13 TeV, in an event sample corresponding to an integrated luminosity of 143 fb-1, collected by ...
the CMS experiment during the 2015-2018 LHC running periods. These excited bc states are observed in the Bc+π+π- invariant mass spectrum, with the ground state Bc+ reconstructed through its decay to J/ψπ+. The two states are reconstructed as two well-resolved peaks, separated in mass by 29.1±1.5(stat)±0.7(syst) MeV. The observation of two peaks, rather than one, is established with a significance exceeding five standard deviations. The mass of the Bc+(2S) meson is measured to be 6871.0±1.2(stat)±0.8(syst)±0.8(Bc+) MeV, where the last term corresponds to the uncertainty in the world-average Bc+ mass. © 2019 CERN for the CMS Collaboration. Published by the American Physical Society under the terms of the »https://creativecommons.org/licenses/by/4.0/» Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.
več
45.
Observation of Single Top Quark Production in Association with a Z Boson in Proton-Proton Collisions at s =13 TeV
Sirunyan, A M; Tumasyan, A; Adam, W ...
Physical review letters,
07/2019, Letnik:
122, Številka:
13
Journal Article
The observation of single top quark production in association with a Z boson and a quark (tZq) is reported. Events from proton-proton collisions at a center-of-mass energy of 13 TeV containing three ...
charged leptons (either electrons or muons) and at least two jets are analyzed. The data were collected with the CMS detector in 2016 and 2017 and correspond to an integrated luminosity of 77.4fb-1. The increased integrated luminosity, a multivariate lepton identification, and a redesigned analysis strategy improve significantly the sensitivity of the analysis compared to previous searches for tZq production. The tZq signal is observed with a significance well over 5 standard deviations. The measured tZq production cross section is σ(pp→tZq→t?+?-q)=111±13(stat)-9+11(syst) fb, for dilepton invariant masses above 30 GeV, in agreement with the standard model expectation. © 2019 CERN.
več
46.
Search for vectorlike leptons in multilepton final states in proton-proton collisions at s =13 TeV
Sirunyan, A M; Tumasyan, A; Adam, W ...
Physical review. D,
07/2019, Letnik:
100, Številka:
5
Journal Article
A search for vectorlike leptons in multilepton final states is presented. The data sample corresponds to an integrated luminosity of 77.4 fb-1 of proton-proton collisions at a center-of-mass energy ...
of 13 TeV collected by the CMS experiment at the LHC in 2016 and 2017. Events are categorized by the multiplicity of electrons, muons, and hadronically decaying τ leptons. The missing transverse momentum and the scalar sum of the lepton transverse momenta are used to distinguish the signal from background. The observed results are consistent with the expectations from the standard model hypothesis. The existence of a vectorlike lepton doublet, coupling to the third-generation standard model leptons in the mass range of 120-790 GeV, is excluded at 95% confidence level. These are the most stringent limits yet on the production of a vectorlike lepton doublet, coupling to the third-generation standard model leptons.
več
47.
Measurement of the top quark polarization and t t spin correlations using dilepton final states in proton-proton collisions at s =13 TeV
Sirunyan, A M; Tumasyan, A; Adam, W ...
Physical review. D,
07/2019, Letnik:
100, Številka:
7
Journal Article
Measurements of the top quark polarization and top quark pair (tt) spin correlations are presented using events containing two oppositely charged leptons (e+e-, e±μ or μ+μ-) produced in proton-proton ...
collisions at a center-of-mass energy of 13 TeV. The data were recorded by the CMS experiment at the LHC in 2016 and correspond to an integrated luminosity of 35.9 fb-1. A set of parton-level normalized differential cross sections, sensitive to each of the independent coefficients of the spin-dependent parts of the tt production density matrix, is measured for the first time at 13 TeV. The measured distributions and extracted coefficients are compared with standard model predictions from simulations at next-to-leading-order (NLO) accuracy in quantum chromodynamics (QCD), and from NLO QCD calculations including electroweak corrections. All measurements are found to be consistent with the expectations of the standard model. The normalized differential cross sections are used in fits to constrain the anomalous chromomagnetic and chromoelectric dipole moments of the top quark to -0.24<CtG/Λ2<0.07 TeV-2 and -0.33<CtGI/Λ2<0.20 TeV-2, respectively, at the 95% confidence level. © 2019 CERN.
več
48.
Search for associated production of a Higgs boson and a single top quark in proton-proton collisions at s =13 TeV
Sirunyan, A M; Tumasyan, A; Adam, W ...
Physical review. D,
07/2019, Letnik:
99, Številka:
9
Journal Article
A search is presented for the production of a Higgs boson in association with a single top quark, based on data collected in 2016 by the CMS experiment at the LHC at a center-of-mass energy of 13 ...
TeV, which corresponds to an integrated luminosity of 35.9 fb-1. The production cross section for this process is highly sensitive to the absolute values of the top quark Yukawa coupling, yt; the Higgs boson coupling to vector bosons, gHVV; and, uniquely, their relative sign. Analyses using multilepton signatures, targeting H→WW, H→ττ, and H→ZZ decay modes, and signatures with a single lepton and a bb pair, targeting the H→bb decay, are combined with a reinterpretation of a measurement in the H→γγ channel to constrain yt. For a standard model-like value of gHVV, the data favor positive values of yt and exclude values of yt below about -0.9ytSM.
več
49.
Measurement of the top quark Yukawa coupling from t t kinematic distributions in the lepton+jets final state in proton-proton collisions at s =13 TeV
Sirunyan, A M; Tumasyan, A; Adam, W ...
Physical review. D,
07/2019, Letnik:
100, Številka:
7
Journal Article
Results are presented for an extraction of the top quark Yukawa coupling from top quark-antiquark (tt) kinematic distributions in the lepton plus jets final state in proton-proton collisions, based ...
on data collected by the CMS experiment at the LHC at s=13 TeV, corresponding to an integrated luminosity of 35.8 fb-1. Corrections from weak boson exchange, including Higgs bosons, between the top quarks can produce large distortions of differential distributions near the energy threshold of tt production. Therefore, precise measurements of these distributions are sensitive to the Yukawa coupling. Top quark events are reconstructed with at least three jets in the final state, and a novel technique is introduced to reconstruct the tt system for events with one missing jet. This technique enhances the experimental sensitivity in the low invariant mass region, Mtt. The data yields in Mtt, the rapidity difference |yt-yt|, and the number of reconstructed jets are compared with distributions representing different Yukawa couplings. These comparisons are used to measure the ratio of the top quark Yukawa coupling to its standard model predicted value to be 1.07-0.43+0.34 with an upper limit of 1.67 at the 95% confidence level. © 2019 CERN.
več
50.
Search for pair production of vectorlike quarks in the fully hadronic final state
Sirunyan, A M; Tumasyan, A; Adam, W ...
Physical review. D,
07/2019, Letnik:
100, Številka:
7
Journal Article
The results of two searches for pair production of vectorlike T or B quarks in fully hadronic final states are presented, using data from the CMS experiment at a center-of-mass energy of 13 TeV. The ...
data were collected at the LHC during 2016 and correspond to an integrated luminosity of 35.9 fb-1. A cut-based analysis specifically targets the bW decay mode of the T quark and allows for the reconstruction of the T quark candidates. In a second analysis, a multiclassification algorithm, the 'boosted event shape tagger,' is deployed to label candidate jets as originating from top quarks, and W, Z, and H. Candidate events are categorized according to the multiplicities of identified jets, and the scalar sum of all observed jet momenta is used to discriminate signal events from the quantum chromodynamics multijet background. Both analyses probe all possible branching fraction combinations of the T and B quarks and set limits at 95% confidence level on their masses, ranging from 740 to 1370 GeV. These results represent a significant improvement relative to existing searches in the fully hadronic final state. © 2019 CERN.
več
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