Publications
1367 results found
Tumasyan A, Adam W, Andrejkovic JW, et al., 2022, Inclusive nonresonant multilepton probes of new phenomena at root s=13 TeV, Physical Review D: Particles, Fields, Gravitation and Cosmology, Vol: 105, ISSN: 1550-2368
An inclusive search for nonresonant signatures of beyond the standard model (SM) phenomena in events with three or more charged leptons, including hadronically decaying τ leptons, is presented. The analysis is based on a data sample corresponding to an integrated luminosity of 138 fb−1 of proton-proton collisions at √s=13 TeV, collected by the CMS experiment at the LHC in 2016–2018. Events are categorized based on the lepton and b-tagged jet multiplicities and various kinematic variables. Three scenarios of physics beyond the SM are probed, and signal-specific boosted decision trees are used for enhancing sensitivity. No significant deviations from the background expectations are observed. Lower limits are set at 95% confidence level on the mass of type-III seesaw heavy fermions in the range 845–1065 GeV for various decay branching fraction combinations to SM leptons. Doublet and singlet vectorlike τ lepton extensions of the SM are excluded for masses below 1045 GeV and in the mass range 125–150 GeV, respectively. Scalar leptoquarks decaying exclusively to a top quark and a lepton are excluded below 1.12–1.42 TeV, depending on the lepton flavor. For the type-III seesaw as well as the vectorlike doublet model, these constraints are the most stringent to date. For the vectorlike singlet model, these are the first constraints from the LHC experiments. Detailed results are also presented to facilitate alternative theoretical interpretations.
Tumasyan A, Adam W, Andrejkovic JW, et al., 2022, Inclusive nonresonant multilepton probes of new phenomena at √s=13 TeV, Physical Review D, Vol: 105, Pages: 1-52, ISSN: 2470-0010
An inclusive search for nonresonant signatures of beyond the standard model (SM) phenomena in events with three or more charged leptons, including hadronically decaying τ leptons, is presented. The analysis is based on a data sample corresponding to an integrated luminosity of 138 fb−1 of proton-proton collisions at √s=13 TeV, collected by the CMS experiment at the LHC in 2016–2018. Events are categorized based on the lepton and b-tagged jet multiplicities and various kinematic variables. Three scenarios of physics beyond the SM are probed, and signal-specific boosted decision trees are used for enhancing sensitivity. No significant deviations from the background expectations are observed. Lower limits are set at 95% confidence level on the mass of type-III seesaw heavy fermions in the range 845–1065 GeV for various decay branching fraction combinations to SM leptons. Doublet and singlet vectorlike τ lepton extensions of the SM are excluded for masses below 1045 GeV and in the mass range 125–150 GeV, respectively. Scalar leptoquarks decaying exclusively to a top quark and a lepton are excluded below 1.12–1.42 TeV, depending on the lepton flavor. For the type-III seesaw as well as the vectorlike doublet model, these constraints are the most stringent to date. For the vectorlike singlet model, these are the first constraints from the LHC experiments. Detailed results are also presented to facilitate alternative theoretical interpretations.
Tumasyan A, Adam W, Ambrogi F, et al., 2022, Observation of B-s(0) mesons and measurement of the B-s(0)/B+ yield ratio in PbPb collisions at root S-NN=5.02 TeV, Modern Physics Letters B, Vol: 829, Pages: 1-25, ISSN: 0217-9849
The B0s and B+ production yields are measured in PbPb collisions at a center-of-mass energy pernucleon pair of 5.02 TeV. The data sample, collected with the CMS detector at the LHC, correspondsto an integrated luminosity of 1.7 nb−1. The mesons are reconstructed in the exclusive decay channelsB0s → J/ψ(μ+μ−)φ(K+K−) and B+ → J/ψ(μ+μ−)K+, in the transverse momentum range 7–50 GeV/cand absolute rapidity 0–2.4. The B0s meson is observed with a statistical significance in excess of fivestandard deviations for the first time in nucleus-nucleus collisions. The measurements are performed asfunctions of the transverse momentum of the B mesons and of the PbPb collision centrality. The ratioof production yields of B0s and B+ is measured and compared to theoretical models that include quarkrecombination effects.
Tumasyan A, Adam W, Andrejkovic JW, et al., 2022, Analysis of the CP structure of the Yukawa coupling between the Higgs boson and tau leptons in proton-proton collisions at root s=13 TeV, The Journal of High Energy Physics, Vol: 2022, Pages: 1-67, ISSN: 1029-8479
The first measurement of the CP structure of the Yukawa coupling between the Higgs boson and τ leptons is presented. The measurement is based on data collected in proton-proton collisions at s√ = 13 TeV by the CMS detector at the LHC, corresponding to an integrated luminosity of 137 fb−1. The analysis uses the angular correlation between the decay planes of τ leptons produced in Higgs boson decays. The effective mixing angle between CP-even and CP-odd τ Yukawa couplings is found to be −1 ± 19°, compared to an expected value of 0 ± 21° at the 68.3% confidence level. The data disfavour the pure CP-odd scenario at 3.0 standard deviations. The results are compatible with predictions for the standard model Higgs boson.
Adam W, Bergauer T, Damanakis K, et al., 2022, Beam test performance of a prototype module with Short Strip ASICs for the CMS HL-LHC tracker upgrade, JOURNAL OF INSTRUMENTATION, Vol: 17, ISSN: 1748-0221
Tumasyan A, Adam W, Andrejkovic JW, et al., 2022, Observation of B<SUP>0</SUP>→ψ(2S)K<sub>S</sub><SUP>0</SUP>π<SUP>+</SUP>π<SUP>-</SUP> and B<sub>s</sub><SUP>0</SUP>→ψ(2S)K<sub>S</sub><SUP>0</SUP> decays, Publisher: SPRINGER
Tumasyan A, Adam W, Andrejkovic JW, et al., 2022, Measurement of the production cross section for Z plus b jets in proton-proton collisions at ?s=13 TeV, Physical Review D: Particles, Fields, Gravitation and Cosmology, Vol: 105, ISSN: 1550-2368
The measurement of the cross section for the production of a Z boson, decaying to dielectrons or dimuons, in association with at least one bottom quark jet is performed with proton-proton collision data at √s=13 TeV. The data sample corresponds to an integrated luminosity of 137 fb−1, collected by the CMS experiment at the LHC during 2016–2018. The integrated cross sections for Z+≥1 b jet and Z+≥2 b jets are reported for the electron, muon, and combined channels. The fiducial cross sections in the combined channel are 6.52±0.04(stat)±0.40(syst)±0.14(theo) pb for Z+≥1 b jet and 0.65±0.03(stat)±0.07(syst)±0.02(theo) pb for Z+≥2 b jets. The differential cross section distributions are measured as functions of various kinematic observables that are useful for precision tests of perturbative quantum chromodynamics predictions. The ratios of integrated and differential cross sections for Z+≥2b jets and Z+≥1 b jet processes are also determined. The value of the integrated cross section ratio measured in the combined channel is 0.100±0.005(stat)±0.007(syst)±0.003(theo). All measurements are compared with predictions from various event generators.
Tumasyan A, Adam W, Andrejkovic JW, et al., 2022, Measurement of the production cross section for Z+b jets in proton-proton collisions at √s=13 TeV, Physical Review D, Vol: 105, Pages: 1-34, ISSN: 2470-0010
The measurement of the cross section for the production of a Z boson, decaying to dielectrons or dimuons, in association with at least one bottom quark jet is performed with proton-proton collision data at √s=13 TeV. The data sample corresponds to an integrated luminosity of 137 fb−1, collected by the CMS experiment at the LHC during 2016–2018. The integrated cross sections for Z+≥1 b jet and Z+≥2 b jets are reported for the electron, muon, and combined channels. The fiducial cross sections in the combined channel are 6.52±0.04(stat)±0.40(syst)±0.14(theo) pb for Z+≥1 b jet and 0.65±0.03(stat)±0.07(syst)±0.02(theo) pb for Z+≥2 b jets. The differential cross section distributions are measured as functions of various kinematic observables that are useful for precision tests of perturbative quantum chromodynamics predictions. The ratios of integrated and differential cross sections for Z+≥2b jets and Z+≥1 b jet processes are also determined. The value of the integrated cross section ratio measured in the combined channel is 0.100±0.005(stat)±0.007(syst)±0.003(theo). All measurements are compared with predictions from various event generators.
Tumasyan A, Adam W, Andrejkovic JW, et al., 2022, Observation of B 0 → ψ (2S)K S 0 π + π - and B s 0 → ψ (2S)K S 0 decays, Eur Phys J C Part Fields, Vol: 82, ISSN: 1434-6044
Using a data sample of s√=13TeV proton-proton collisions collected by the CMS experiment at the LHC in 2017 and 2018 with an integrated luminosity of 103~fb−1, the B0s→ψ(2S)K0S and B0→ψ(2S)K0Sπ+π− decays are observed with significances exceeding 5 standard deviations. The resulting branching fraction ratios, measured for the first time, correspond to B(B0s→ψ(2S)K0S)/B(B0→ψ(2S)K0S)=(3.33±0.69(stat)±0.11(syst)±0.34(fs/fd))×10−2 and B(B0→ψ(2S)K0Sπ+π−)/B(B0→ψ(2S)K0S)=0.480±0.013(stat)±0.032(syst), where the last uncertainty in the first ratio is related to the uncertainty in the ratio of production cross sections of B0s and B0 mesons, fs/fd.
Tumasyan A, Adam W, Andrejkovic JW, et al., 2022, Search for invisible decays of the Higgs boson produced via vector boson fusion in proton-proton collisions at √s=13 TeV, Physical Review D, Vol: 105, Pages: 1-36, ISSN: 2470-0010
A search for invisible decays of the Higgs boson produced via vector boson fusion (VBF) has been performed with 101 fb−1 of proton-proton collisions delivered by the LHC at √s=13 TeV and collected by the CMS detector in 2017 and 2018. The sensitivity to the VBF production mechanism is enhanced by constructing two analysis categories, one based on missing transverse momentum and a second based on the properties of jets. In addition to control regions with Z and W boson candidate events, a highly populated control region, based on the production of a photon in association with jets, is used to constrain the dominant irreducible background from the invisible decay of a Z boson produced in association with jets. The results of this search are combined with all previous measurements in the VBF topology, based on data collected in 2012 (at √s=8 TeV), 2015, and 2016, corresponding to integrated luminosities of 19.7, 2.3, and 36.3 fb−1, respectively. The observed (expected) upper limit on the invisible branching fraction of the Higgs boson is found to be 0.18 (0.10) at the 95% confidence level, assuming the standard model production cross section. The results are also interpreted in the context of Higgs-portal models.
Tumasyan A, Adam W, Andrejkovic JW, et al., 2022, Search for single production of a vector-like T quark decaying to a top quark and a Z boson in the final state with jets and missing transverse momentum at root s=13 TeV, The Journal of High Energy Physics, Vol: 2022, Pages: 1-49, ISSN: 1029-8479
A search is presented for single production of a vector-like T quark with charge 2/3 e, in the decay channel featuring a top quark and a Z boson, with the top quark decaying hadronically and the Z boson decaying to neutrinos. The search uses data collected by the CMS experiment in proton-proton collisions at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 137 fb−1 recorded at the CERN LHC in 2016–2018. The search is sensitive to a T quark mass between 0.6 and 1.8 TeV with decay widths ranging from negligibly small up to 30% of the T quark mass. Reconstruction strategies for the top quark are based on the degree of Lorentz boosting of its final state. At 95% confidence level, the upper limit on the product of the cross section and branching fraction for a T quark of small decay width varies between 15 and 602 fb, depending on its mass. For a T quark with decay widths between 10 and 30% of its mass, this upper limit ranges between 16 and 836 fb. For most of the studied range, the results provide the best limits to date. This is the first search for single T quark production based on the full Run 2 data set of the LHC.
Tumasyan A, Adam W, Andrejkovic JW, et al., 2022, Measurement of the inclusive and differential t(t)over-bar gamma cross sections in the dilepton channel and effective field theory interpretation in proton-proton collisions at root s=13 TeV, The Journal of High Energy Physics, Vol: 2022, Pages: 1-59, ISSN: 1029-8479
The production cross section of a top quark pair in association with a photon is measured in proton-proton collisions in the decay channel with two oppositely charged leptons (e±μ∓, e+e−, or μ+μ−). The measurement is performed using 138 fb−1 of proton-proton collision data recorded by the CMS experiment at s√ = 13 TeV during the 2016–2018 data-taking period of the CERN LHC. A fiducial phase space is defined such that photons radiated by initial-state particles, top quarks, or any of their decay products are included. An inclusive cross section of 175.2 ± 2.5(stat) ± 6.3(syst) fb is measured in a signal region with at least one jet coming from the hadronization of a bottom quark and exactly one photon with transverse momentum above 20 GeV. Differential cross sections are measured as functions of several kinematic observables of the photon, leptons, and jets, and compared to standard model predictions. The measurements are also interpreted in the standard model effective field theory framework, and limits are found on the relevant Wilson coefficients from these results alone and in combination with a previous CMS measurement of the tt¯γ production process using the lepton+jets final state.
Scandale W, Arduini G, Assmann R, et al., 2022, Feasibility of crystal-assisted collimation in the CERN accelerator complex, INTERNATIONAL JOURNAL OF MODERN PHYSICS A, Vol: 37, ISSN: 0217-751X
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Tumasyan A, Adam W, Andrejkovic JW, et al., 2022, Search for higgsinos decaying to two Higgs bosons and missing transverse momentum in proton-proton collisions at root s=13 TeV, The Journal of High Energy Physics, Vol: 2022, Pages: 1-65, ISSN: 1029-8479
Results are presented from a search for physics beyond the standard model in proton-proton collisions at s√ = 13 TeV in channels with two Higgs bosons, each decaying via the process H → bb¯¯¯, and large missing transverse momentum. The search uses a data sample corresponding to an integrated luminosity of 137 fb−1 collected by the CMS experiment at the CERN LHC. The search is motivated by models of supersymmetry that predict the production of neutralinos, the neutral partners of the electroweak gauge and Higgs bosons. The observed event yields in the signal regions are found to be consistent with the standard model background expectations. The results are interpreted using simplified models of supersymmetry. For the electroweak production of nearly mass-degenerate higgsinos, each of whose decay chains yields a neutralino (χ∼01) that in turn decays to a massless goldstino and a Higgs boson, (χ∼01) masses in the range 175 to 1025 GeV are excluded at 95% confidence level. For the strong production of gluino pairs decaying via a slightly lighter (χ∼02) to H and a light (χ∼01), gluino masses below 2330 GeV are excluded.
Tumasyan A, Adam W, Andrejkovic JW, et al., 2022, Search for heavy resonances decaying to a pair of Lorentz-boosted Higgs bosons in final states with leptons and a bottom quark pair at root s=13 TeV, The Journal of High Energy Physics, Vol: 2022, Pages: 1-61, ISSN: 1029-8479
A search for new heavy resonances decaying to a pair of Higgs bosons (HH) in proton-proton collisions at a center-of-mass energy of 13 TeV is presented. Data were collected with the CMS detector at the LHC in 2016–2018, corresponding to an integrated luminosity of 138 fb−1. Resonances with a mass between 0.8 and 4.5 TeV are considered using events in which one Higgs boson decays into a bottom quark pair and the other into final states with either one or two charged leptons. Specifically, the single-lepton decay channel HH→bb¯¯¯WW∗→bb¯¯¯ℓvqq¯¯¯′ and the dilepton decay channels HH→bb¯¯¯WW∗→bb¯¯¯ℓvℓv and HH→bb¯¯¯ττ→bb¯¯¯ℓvvℓvv are examined, where ℓ in the final state corresponds to an electron or muon. The signal is extracted using a two-dimensional maximum likelihood fit of the H→bb¯¯¯ jet mass and HH invariant mass distributions. No significant excess above the standard model expectation is observed in data. Model-independent exclusion limits are placed on the product of the cross section and branching fraction for narrow spin-0 and spin-2 massive bosons decaying to HH. The results are also interpreted in the context of radion and bulk graviton production in models with a warped extra spatial dimension. The results provide the most stringent limits to date for X → HH signatures with final-state leptons and at some masses provide the most sensitive limits of all X → HH searches.
Sirunyan AM, Tumasyan A, Adam W, et al., 2022, Search for new physics in dijet angular distributions using proton-proton collisions at √<i>s</i> = 13TeV and constraints on dark matter and other models (vol 78, 789, 2018), EUROPEAN PHYSICAL JOURNAL C, Vol: 82, ISSN: 1434-6044
Tumasyan A, Adam W, Andrejkovic JW, et al., 2022, Search for electroweak production of charginos and neutralinos in proton-proton collisions at root s=13 TeV, The Journal of High Energy Physics, Vol: 2022, Pages: 1-73, ISSN: 1029-8479
A direct search for electroweak production of charginos and neutralinos is presented. Events with three or four leptons, with up to two hadronically decaying τ leptons, or two same-sign light leptons are analyzed. The data sample consists of 137 fb−1 of proton-proton collisions with a center of mass energy of 13 TeV, recorded with the CMS detector at the LHC. The results are interpreted in terms of several simplified models. These represent a broad range of production and decay scenarios for charginos and neutralinos. A parametric neural network is used to target several of the models with large backgrounds. In addition, results using orthogonal search regions are provided for all the models, simplifying alternative theoretical interpretations of the results. Depending on the model hypotheses, charginos and neutralinos with masses up to values between 300 and 1450 GeV are excluded at 95% confidence level.
Tumasyan A, Adam W, Andrejkovic JW, et al., 2022, Measurement of the inclusive tt¯ production cross section in proton-proton collisions at s√ = 5.02 TeV, The Journal of High Energy Physics, Vol: 2022, Pages: 1-38, ISSN: 1029-8479
The top quark pair production cross section is measured in proton-proton collisions at a center-of-mass energy of 5.02 TeV. The data were collected in a special LHC low-energy and low-intensity run in 2017, and correspond to an integrated luminosity of 302 pb−1. The measurement is performed using events with one electron and one muon of opposite charge, and at least two jets. The measured cross section is 60.7 ± 5.0 (stat) ± 2.8 (syst) ± 1.1 (lumi) pb. A combination with the result in the single lepton + jets channel, based on data collected in 2015 at the same center-of-mass energy and corresponding to an integrated luminosity of 27.4 pb−1, is then performed. The resulting measured value is 63.0 ± 4.1 (stat) ± 3.0 (syst+lumi) pb, in agreement with the standard model prediction of 66.8+2.9−3.1 pb.
Tumasyan A, Adam W, Andrejkovic JW, et al., 2022, Precision measurement of the W boson decay branching fractions in proton-proton collisions at ? s=13 TeV, Physical Review D: Particles, Fields, Gravitation and Cosmology, Vol: 105, Pages: 1-31, ISSN: 1550-2368
The leptonic and inclusive hadronic decay branching fractions of the W boson are measured using proton-proton collision data collected at √s=13 TeV by the CMS experiment at the CERN LHC, corresponding to an integrated luminosity of 35.9 fb−1. Events characterized by the production of one or two W bosons are selected and categorized based on the multiplicity and flavor of reconstructed leptons, the number of jets, and the number of jets identified as originating from the hadronization of b quarks. A binned maximum likelihood estimate of the W boson branching fractions is performed simultaneously in each event category. The measured branching fractions of the W boson decaying into electron, muon, and tau lepton final states are (10.83±0.10)%, (10.94±0.08)%, and (10.77±0.21)%, respectively, consistent with lepton flavor universality for the weak interaction. The average leptonic and inclusive hadronic decay branching fractions are estimated to be (10.89±0.08)% and (67.32±0.23)%, respectively. Based on the hadronic branching fraction, three standard model quantities are subsequently derived: the sum of squared elements in the first two rows of the Cabibbo–Kobayashi–Maskawa (CKM) matrix ∑ij|Vij|2=1.984±0.021, the CKM element |Vcs|=0.967±0.011, and the strong coupling constant at the W boson mass scale, αS(m2W)=0.095±0.033.
Tumasyan A, Adam W, Andrejkovic JW, et al., 2022, Measurement of the inclusive t(t)over-bar production cross section in proton-proton collisions at root s=5.02 TeV, The Journal of High Energy Physics, Pages: 1-38, ISSN: 1029-8479
The top quark pair production cross section is measured in proton-proton collisions at a center-of-mass energy of 5.02 TeV. The data were collected in a special LHC low-energy and low-intensity run in 2017, and correspond to an integrated luminosity of 302 pb−1. The measurement is performed using events with one electron and one muon of opposite charge, and at least two jets. The measured cross section is 60.7 ± 5.0 (stat) ± 2.8 (syst) ± 1.1 (lumi) pb. A combination with the result in the single lepton + jets channel, based on data collected in 2015 at the same center-of-mass energy and corresponding to an integrated luminosity of 27.4 pb−1, is then performed. The resulting measured value is 63.0 ± 4.1 (stat) ± 3.0 (syst+lumi) pb, in agreement with the standard model prediction of 66.8+2.9−3.1 pb.
Sirunyan AM, Tumasyan A, Adam W, et al., 2022, Measurement of exclusive Υ photoproduction from protons in pPb collisions at √s<sub>NN</sub> = 5.02 TeV (vol 79, 277, 2019), EUROPEAN PHYSICAL JOURNAL C, Vol: 82, ISSN: 1434-6044
Tumasyan A, Adam W, Andrejkovic JW, et al., 2022, Search for heavy resonances decaying to ZZ or ZW and axion-like particles mediating nonresonant ZZ or ZH production at root s=13 TeV, The Journal of High Energy Physics, Vol: 2022, Pages: 1-49, ISSN: 1029-8479
A search has been performed for heavy resonances decaying to ZZ or ZW and for axion-like particles (ALPs) mediating nonresonant ZZ or ZH production, in final states with two charged leptons (ℓ = e, μ) produced by the decay of a Z boson, and two quarks produced by the decay of a Z, W, or Higgs boson H. The analysis is sensitive to resonances with masses in the range 450 to 2000 GeV. Two categories are defined corresponding to the merged or resolved reconstruction of the hadronically decaying boson. The search is based on data collected during 2016–2018 by the CMS experiment at the LHC in proton-proton collisions at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 138 fb−1. No significant excess is observed in the data above the standard model background expectation. Upper limits on the production cross section of heavy, narrow spin-2 and spin-1 resonances are derived as functions of the resonance mass, and exclusion limits on the production of bulk graviton particles and W′ bosons are calculated in the framework of the warped extra dimensions and heavy vector triplet models, respectively. In addition, upper limits on the ALP-mediated diboson production cross section and ALP couplings to standard model particles are obtained in the framework of linear and chiral effective field theories. These are the first limits on nonresonant ALP-mediated ZZ and ZH production obtained by the LHC experiments.
Tumasyan A, Adam W, Andrejkovic JW, et al., 2022, Search for supersymmetry in final states with two or three soft leptons and missing transverse momentum in proton-proton collisions at root s=13 TeV, The Journal of High Energy Physics, Vol: 2022, Pages: 1-58, ISSN: 1029-8479
A search for supersymmetry in events with two or three low-momentum leptons and missing transverse momentum is performed. The search uses proton-proton collisions at s√ = 13 TeV collected in the three-year period 2016–2018 by the CMS experiment at the LHC and corresponding to an integrated luminosity of up to 137 fb−1. The data are found to be in agreement with expectations from standard model processes. The results are interpreted in terms of electroweakino and top squark pair production with a small mass difference between the produced supersymmetric particles and the lightest neutralino. For the electroweakino interpretation, two simplified models are used, a wino-bino model and a higgsino model. Exclusion limits at 95% confidence level are set on χ∼02/χ∼±1 masses up to 275 GeV for a mass difference of 10 GeV in the wino-bino case, and up to 205(150) GeV for a mass difference of 7.5 (3) GeV in the higgsino case. The results for the higgsino are further interpreted using a phenomenological minimal supersymmetric standard model, excluding the higgsino mass parameter μ up to 180 GeV with the bino mass parameter M1 at 800 GeV. In the top squark interpretation, exclusion limits are set at top squark masses up to 540 GeV for four-body top squark decays and up to 480 GeV for chargino-mediated decays with a mass difference of 30 GeV.
Sirunyan AM, Tumasyan A, Adam W, et al., 2022, Measurement of the top quark mass with lepton+jets final states using pp collisions at √<i>s</i> = 13TeV (vol 78, 891, 2018), EUROPEAN PHYSICAL JOURNAL C, Vol: 82, ISSN: 1434-6044
Tumasyan A, Adam W, Andrejkovic JW, et al., 2022, Search for long-lived particles decaying into muon pairs in proton-proton collisions at root s=13 TeV collected with a dedicated high-rate data stream, The Journal of High Energy Physics, Vol: 2022, Pages: 1-45, ISSN: 1029-8479
A search for long-lived particles decaying into muon pairs is performed using proton-proton collisions at a center-of-mass energy of 13 TeV, collected by the CMS experiment at the LHC in 2017 and 2018, corresponding to an integrated luminosity of 101 fb−1. The data sets used in this search were collected with a dedicated dimuon trigger stream with low transverse momentum thresholds, recorded at high rate by retaining a reduced amount of information, in order to explore otherwise inaccessible phase space at low dimuon mass and nonzero displacement from the primary interaction vertex. No significant excess of events beyond the standard model expectation is found. Upper limits on branching fractions at 95% confidence level are set on a wide range of mass and lifetime hypotheses in beyond the standard model frameworks with the Higgs boson decaying into a pair of long-lived dark photons, or with a long-lived scalar resonance arising from a decay of a b hadron. The limits are the most stringent to date for substantial regions of the parameter space. These results can be also used to constrain models of displaced dimuons that are not explicitly considered in this paper.
Tumasyan A, Adam W, Andrejkovic JW, et al., 2022, Search for a right-handed W boson and a heavy neutrino in proton-proton collisions at root s=13 TeV, The Journal of High Energy Physics, Vol: 2022, Pages: 1-43, ISSN: 1029-8479
A search is presented for a right-handed W boson (WR) and a heavy neutrino (N), in a final state consisting of two same-flavor leptons (ee or μμ) and two quarks. The search is performed with the CMS experiment at the CERN LHC using a data sample of proton-proton collisions at a center-of-mass energy of 13 TeV corresponding to an integrated luminosity of 138 fb−1. The search covers two regions of phase space, one where the decay products of the heavy neutrino are merged into a single large-area jet, and one where the decay products are well separated. The expected signal is characterized by an excess in the invariant mass distribution of the final-state objects. No significant excess over the standard model background expectations is observed. The observations are interpreted as upper limits on the product of WR production cross sections and branching fractions assuming that couplings are identical to those of the standard model W boson. For N masses mN equal to half the WR mass mWR (mN = 0.2 TeV), mWR is excluded at 95% confidence level up to 4.7 (4.8) and 5.0 (5.4) TeV for the electron and muon channels, respectively. This analysis provides the most stringent limits on the WR mass to date.
Tumasyan A, Adam W, Andrejkovic JW, et al., 2022, Search for a heavy resonance decaying into a top quark and a W boson in the lepton plus jets final state at root s=13 TeV, The Journal of High Energy Physics, Vol: 2022, Pages: 1-43, ISSN: 1029-8479
A search for a heavy resonance decaying into a top quark and a W boson in proton-proton collisions at s√ = 13 TeV is presented. The data analyzed were recorded with the CMS detector at the LHC and correspond to an integrated luminosity of 138 fb−1. The top quark is reconstructed as a single jet and the W boson, from its decay into an electron or muon and the corresponding neutrino. A top quark tagging technique based on jet clustering with a variable distance parameter and simultaneous jet grooming is used to identify jets from the collimated top quark decay. The results are interpreted in the context of two benchmark models, where the heavy resonance is either an excited bottom quark b∗ or a vector-like quark B. A statistical combination with an earlier search by the CMS Collaboration in the all-hadronic final state is performed to place upper cross section limits on these two models. The new analysis extends the lower range of resonance mass probed from 1.4 down to 0.7 TeV. For left-handed, right-handed, and vector-like couplings, b∗ masses up to 3.0, 3.0, and 3.2 TeV are excluded at 95% confidence level, respectively. The observed upper limits represent the most stringent constraints on the b∗ model to date.
Tumasyan A, Adam W, Bergauer T, et al., 2022, Search for low-mass dilepton resonances in Higgs boson decays to four-lepton final states in proton-proton collisions at root s=13 TeV, European Physical Journal C: Particles and Fields, Vol: 82, ISSN: 1124-1861
A search for low-mass dilepton resonances in Higgs boson decays is conducted in the four-lepton final state. The decay is assumed to proceed via a pair of beyond the standard model particles, or one such particle and a Z boson. The search uses proton–proton collision data collected with the CMS detector at the CERN LHC, corresponding to an integrated luminosity of 137fb−1, at a center-of-mass energy s√=13TeV. No significant deviation from the standard model expectation is observed. Upper limits at 95% confidence level are set on model-independent Higgs boson decay branching fractions. Additionally, limits on dark photon and axion-like particle production, based on two specific models, are reported.
Sirunyan AM, Tumasyan A, Adam W, et al., 2022, Search for heavy Higgs bosons decaying to a top quark pair in proton-proton collisions at √<i>s</i> = 13 TeV (vol 04, 171, 2020), JOURNAL OF HIGH ENERGY PHYSICS, ISSN: 1029-8479
Tumasyan A, Adam W, Andrejkovic JW, et al., 2022, Study of dijet events with large rapidity separation in proton-proton collisions at root s=2.76 TeV, The Journal of High Energy Physics, Vol: 2022, Pages: 1-46, ISSN: 1029-8479
The cross sections for inclusive and Mueller-Navelet dijet production are measured as a function of the rapidity separation between the jets in proton-proton collisions at s√ = 2.76 TeV for jets with transverse momentum pT > 35 GeV and rapidity |y| < 4.7. Various dijet production cross section ratios are also measured. A veto on additional jets with pT > 20 GeV is introduced to improve the sensitivity to the effects of the Balitsky-Fadin-Kuraev-Lipatov (BFKL) evolution. The measurement is compared with the predictions of various Monte Carlo models based on leading-order and next-to-leading-order calculations including the Dokshitzer-Gribov-Lipatov-Altarelli-Parisi leading-logarithm (LL) parton shower as well as the LL BFKL resummation.
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