Publications
1367 results found
Tumasyan A, Adam W, Andrejkovic JW, et al., 2023, Search for narrow resonances in the Formula Presented-tagged dijet mass spectrum in proton-proton collisions at Formula Presented, Physical Review D, Vol: 108, ISSN: 2470-0010
A search is performed for narrow resonances decaying to final states of two jets, with at least one jet originating from a b quark, in proton-proton collisions at s = 13 TeV . The data set corresponds to an integrated luminosity of 138 fb - 1 collected with the CMS detector at the LHC. Jets originating from energetic b hadrons are identified through a b -tagging algorithm that utilizes a deep neural network or the presence of a muon inside a jet. The invariant mass spectrum of jet pairs is well described by a smooth parametrization and no evidence for the production of new particles is observed. Upper limits on the production cross section are set for excited b quarks and other resonances decaying to dijet final states containing b quarks. These limits exclude at 95% confidence level models of Z ′ bosons with masses from 1.8 TeV to 2.4 TeV and of excited b quarks with masses from 1.8 TeV to 4.0 TeV. This is the most stringent exclusion of excited b quarks to date.
Tumasyan A, Adam W, Andrejkovic JW, et al., 2023, Search for CP violation in t t ¯ H and tH production in multilepton channels in proton-proton collisions at √s = 13 TeV, Journal of High Energy Physics, Vol: 2023
The charge-parity (CP) structure of the Yukawa interaction between the Higgs (H) boson and the top quark is measured in a data sample enriched in the t t ¯ H and tH associated production, using 138 fb −1 of data collected in proton-proton collisions at s = 13 TeV by the CMS experiment at the CERN LHC. The study targets events where the H boson decays via H → WW or H → ττ and the top quarks decay via t → Wb: the W bosons decay either leptonically or hadronically, and final states characterized by the presence of at least two leptons are studied. Machine learning techniques are applied to these final states to enhance the separation of CP -even from CP -odd scenarios. Two-dimensional confidence regions are set on κ t and κ~ t, which are respectively defined as the CP -even and CP -odd top-Higgs Yukawa coupling modifiers. No significant fractional CP -odd contributions, parameterized by the quantity | fCPHtt | are observed; the parameter is determined to be | fCPHtt | = 0.59 with an interval of (0.24, 0.81) at 68% confidence level. The results are combined with previous results covering the H → ZZ and H → γγ decay modes, yielding two- and one-dimensional confidence regions on κ t and κ~ t, while | fCPHtt | is determined to be | fCPHtt | = 0.28 with an interval of | fCPHtt | < 0.55 at 68% confidence level, in agreement with the standard model CP -even prediction of | fCPHtt | = 0. [Figure not available: see fulltext.].
Tumasyan A, Adam W, Andrejkovic JW, et al., 2023, Search for direct pair production of supersymmetric partners of τ leptons in the final state with two hadronically decaying τ leptons and missing transverse momentum in proton-proton collisions at Formula Presented, Physical Review D, Vol: 108, ISSN: 2470-0010
A search for the direct production of a pair of τ sleptons, the supersymmetric partners of τ leptons, is presented. Each τ slepton is assumed to decay to a τ lepton and the lightest supersymmetric particle (LSP), which is assumed to be stable and to not interact in the detector, leading to an imbalance in the total reconstructed transverse momentum. The search is carried out in events identified as containing two τ leptons, each decaying to one or more hadrons and a neutrino, and significant transverse momentum imbalance. In addition to scenarios in which the τ sleptons decay promptly, the search also addresses scenarios in which the τ sleptons have sufficiently long lifetimes to give rise to nonprompt τ leptons. The data were collected in proton-proton collisions at a center-of-mass energy of 13 TeV at the CERN LHC with the CMS detector in 2016-2018, and correspond to an integrated luminosity of 138 fb - 1 . No significant excess is seen with respect to standard model expectations. Upper limits on cross sections for the pair production of τ sleptons are obtained in the framework of simplified models. In a scenario in which the τ sleptons are superpartners of left-handed τ leptons, and each undergoes a prompt decay to a τ lepton and a nearly massless LSP, τ slepton masses between 115 and 340 GeV are excluded. In a scenario in which the lifetime of the τ sleptons corresponds to c τ 0 = 0.1 mm , where τ 0 represents the mean proper lifetime of the τ slepton, masses between 150 and 220 GeV are excluded.
Tumasyan A, Adam W, Andrejkovic JW, et al., 2023, Measurements of Higgs boson production in the decay channel with a pair of τ leptons in proton–proton collisions at √s=13 TeV, European Physical Journal C, Vol: 83, ISSN: 1434-6044
Measurements of Higgs boson production, where the Higgs boson decays into a pair of τ leptons, are presented, using a sample of proton-proton collisions collected with the CMS experiment at a center-of-mass energy of [InlineEquation not available: see fulltext.], corresponding to an integrated luminosity of 138 fb-1 . Three analyses are presented. Two are targeting Higgs boson production via gluon fusion and vector boson fusion: a neural network based analysis and an analysis based on an event categorization optimized on the ratio of signal over background events. These are complemented by an analysis targeting vector boson associated Higgs boson production. Results are presented in the form of signal strengths relative to the standard model predictions and products of cross sections and branching fraction to τ leptons, in up to 16 different kinematic regions. For the simultaneous measurements of the neural network based analysis and the analysis targeting vector boson associated Higgs boson production signal strengths are found to be 0.82 ± 0.11 for inclusive Higgs boson production, 0.67 ± 0.19 (0.81 ± 0.17) for the production mainly via gluon fusion (vector boson fusion), and 1.79 ± 0.45 for vector boson associated Higgs boson production.
Tumasyan A, Adam W, Bergauer T, et al., 2023, Search for CP violating top quark couplings in pp collisions at √s = 13 TeV, Journal of High Energy Physics, Vol: 2023
Results are presented from a search for CP violation in top quark pair production, using proton-proton collisions at a center-of-mass energy of 13 TeV. The data used for this analysis consist of final states with two charged leptons collected by the CMS experiment, and correspond to an integrated luminosity of 35.9 fb−1. The search uses two observables, O1 and O3, which are Lorentz scalars. The observable O1 is constructed from the four-momenta of the charged leptons and the reconstructed top quarks, while O3 consists of the four-momenta of the charged leptons and the b quarks originating from the top quarks. Asymmetries in these observables are sensitive to CP violation, and their measurement is used to determine the chromoelectric dipole moment of the top quark. The results are consistent with the expectation from the standard model. [Figure not available: see fulltext.].
Tumasyan A, Adam W, Andrejkovic JW, et al., 2023, Search for nonresonant Higgs boson pair production in the four leptons plus twob jets final state in proton-proton collisions at √s=13 TeV, JOURNAL OF HIGH ENERGY PHYSICS, ISSN: 1029-8479
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- Citations: 1
Tumasyan A, Adam W, Andrejkovic JW, et al., 2023, Search for CP violation using t (t)over-bar events in the lepton plus jets channel in pp collisions at √s=13 TeV, JOURNAL OF HIGH ENERGY PHYSICS, ISSN: 1029-8479
Tumasyan A, Adam W, Andrejkovic JW, et al., 2023, Search for top squarks in the four-body decay mode with single lepton final states in proton-proton collisions at √s=13 TeV, JOURNAL OF HIGH ENERGY PHYSICS, ISSN: 1029-8479
Tumasyan A, Collaboration TCMS, Adam W, et al., 2023, Observation of electroweak W<SUP>+</SUP>W<SUP>-</SUP> pair production in association with two jets in proton-proton collisions at √s=13 TeV, PHYSICS LETTERS B, Vol: 841, ISSN: 0370-2693
Rossi R, Esposito L, Pesaresi M, et al., 2023, Track reconstruction and analysis of particle interactions in short bent crystals, Journal of Instrumentation, Vol: 18
Measurements of the interaction of positively charged particles with bent crystals were obtained by developing a new and consolidated analysis method, for the use of UA9 collaboration. The method was deployed to characterize crystals with a length of a few mm along the beam direction and a bending angle in the order of 10 μrad to 100 μrad, typically exploited in the CERN accelerators. To assess their properties and quality, the crystals have been investigated in the Super Proton Synchrotron North Area with a beam of mixed hadrons at 180 GeV. The UA9 telescopic tracker has been used to collect the data. Some of them are used in the present study to describe and validate the applied data-analysis methodology.
Tumasyan A, Adam W, Andrejkovic JW, et al., 2023, Search for Higgs boson decays to a Z boson and a photon in proton-proton collisions at √s=13 TeV, JOURNAL OF HIGH ENERGY PHYSICS, ISSN: 1029-8479
Tumasyan A, Adam W, Andrejkovic JW, et al., 2023, Search for heavy resonances and quantum black holes in eμ, eτ, and μτ final states in proton-proton collisions at √<i>s</i>=13 TeV, JOURNAL OF HIGH ENERGY PHYSICS, ISSN: 1029-8479
Tumasyan A, Adam W, Andrejkovic JW, et al., 2023, Search for long-lived particles decaying to a pair of muons in proton-proton collisions at √s=13 TeV, JOURNAL OF HIGH ENERGY PHYSICS, ISSN: 1029-8479
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- Citations: 1
Tumasyan A, Adam W, Andrejkovic JW, et al., 2023, Strange hadron collectivity in pPb and PbPb collisions, JOURNAL OF HIGH ENERGY PHYSICS, ISSN: 1029-8479
Adam W, Bergauer T, Damanakis K, et al., 2023, Test beam performance of a CBC3-based mini-module for the Phase-2 CMS Outer Tracker before and after neutron irradiation, JOURNAL OF INSTRUMENTATION, Vol: 18, ISSN: 1748-0221
Tumasyan A, Adam W, Andrejkovic JW, et al., 2023, Publisher Correction: Observation of triple J/ψ meson production in proton-proton collisions (Nature Physics, (2023), 19, 3, (338-350), 10.1038/s41567-022-01838-y), Nature Physics, Vol: 19, ISSN: 1745-2473
Correction to: Nature Physics. Published online 19 January 2023. In the version of this article initially published, the first affiliation—Yerevan Physics Institute, Yerevan, Armenia—was missing from the list of author affiliations and has now been inserted in the HTML and PDF versions of the article.
Sirunyan AM, Tumasyan A, Adam W, et al., 2023, Measurement of prompt and nonprompt charmonium suppression in PbPb collisions at 5.02 TeV (vol 78, 509, 2018), EUROPEAN PHYSICAL JOURNAL C, Vol: 83, ISSN: 1434-6044
Tumasyan A, Adam W, Andrejkovic JW, et al., 2023, Observation of triple J/ψ meson production in proton-proton collisions, NATURE PHYSICS, ISSN: 1745-2473
Tumasyan A, Adam W, Andrejkovic JW, et al., 2023, Publisher Correction: Observation of triple J/ψ meson production in proton-proton collisions (Nature Physics, (2023), 19, 3, (338-350), 10.1038/s41567-022-01838-y), Nature Physics, ISSN: 1745-2473
Correction to: Nature Physics, published online 19 January 2023. In the version of the article initially published, the second affiliation of T. Elkafrawy was incorrect and is now shown as Ain Shams University, Cairo, Egypt in the HTML and PDF versions of the article.
Fedi G, Fiorendi S, Holmberg M, et al., 2023, Lessons learnt from the first vertical slice of the CMS Outer Tracker, Topical Workshop on Electronics for Particle Physics (TWEPP), Publisher: IOP Publishing Ltd, ISSN: 1748-0221
Tumasyan A, Adam W, Andrejkovic JW, et al., 2023, CMS pythia 8 colour reconnection tunes based on underlying-event data., Eur Phys J C Part Fields, Vol: 83, ISSN: 1434-6044
New sets of parameter tunes for two of the colour reconnection models, quantum chromodynamics-inspired and gluon-move, implemented in the pythia 8 event generator, are obtained based on the default CMS pythia 8 underlying-event tune, CP5. Measurements sensitive to the underlying event performed by the CMS experiment at centre-of-mass energies s=7 and 13TeV, and by the CDF experiment at 1.96TeV are used to constrain the parameters of colour reconnection models and multiple-parton interactions simultaneously. The new colour reconnection tunes are compared with various measurements at 1.96, 7, 8, and 13TeV including measurements of the underlying-event, strange-particle multiplicities, jet substructure observables, jet shapes, and colour flow in top quark pair (tt¯) events. The new tunes are also used to estimate the uncertainty related to colour reconnection modelling in the top quark mass measurement using the decay products of tt¯ events in the semileptonic channel at 13TeV.
Tumasyan A, Adam W, Andrejkovic JW, et al., 2023, Measurement of the differential tt¯ production cross section as a function of the jet mass and extraction of the top quark mass in hadronic decays of boosted top quarks., Eur Phys J C Part Fields, Vol: 83, ISSN: 1434-6044
A measurement of the jet mass distribution in hadronic decays of Lorentz-boosted top quarks is presented. The measurement is performed in the lepton + jets channel of top quark pair production (tt¯) events, where the lepton is an electron or muon. The products of the hadronic top quark decay are reconstructed using a single large-radius jet with transverse momentum greater than 400GeV. The data were collected with the CMS detector at the LHC in proton-proton collisions and correspond to an integrated luminosity of 138fb-1. The differential tt¯ production cross section as a function of the jet mass is unfolded to the particle level and is used to extract the top quark mass. The jet mass scale is calibrated using the hadronic W boson decay within the large-radius jet. The uncertainties in the modelling of the final state radiation are reduced by studying angular correlations in the jet substructure. These developments lead to a significant increase in precision, and a top quark mass of 173.06±0.84GeV.
Tumasyan A, Adam W, Andrejkovic JW, et al., 2023, Search for light Higgs bosons from supersymmetric cascade decays in pp collisions at s=13TeV., Eur Phys J C Part Fields, Vol: 83, ISSN: 1434-6044
A search is reported for pairs of light Higgs bosons (H1) produced in supersymmetric cascade decays in final states with small missing transverse momentum. A data set of LHC pp collisions collected with the CMS detector at s=13TeV and corresponding to an integrated luminosity of 138fb-1 is used. The search targets events where both H1 bosons decay into pairs that are reconstructed as large-radius jets using substructure techniques. No evidence is found for an excess of events beyond the background expectations of the standard model (SM). Results from the search are interpreted in the next-to-minimal supersymmetric extension of the SM, where a "singlino" of small mass leads to squark and gluino cascade decays that can predominantly end in a highly Lorentz-boosted singlet-like H1 and a singlino-like neutralino of small transverse momentum. Upper limits are set on the product of the squark or gluino pair production cross section and the square of the branching fraction of the H1 in a benchmark model containing almost mass-degenerate gluinos and light-flavour squarks. Under the assumption of an SM-like branching fraction, H1 bosons with masses in the range 40-120GeV arising from the decays of squarks or gluinos with a mass of 1200-2500GeV are excluded at 95% confidence level.
Tumasyan A, Adam W, Andrejkovic JW, et al., 2023, Azimuthal correlations in Z +jets events in proton-proton collisions at s=13TeV., Eur Phys J C Part Fields, Vol: 83, ISSN: 1434-6044
The production of Z bosons associated with jets is measured in pp collisions at s=13TeV with data recorded with the CMS experiment at the LHC corresponding to an integrated luminosity of 36.3fb-1. The multiplicity of jets with transverse momentum pT>30GeV is measured for different regions of the Z boson's pT(Z), from lower than 10GeV to higher than 100GeV. The azimuthal correlation Δϕ between the Z boson and the leading jet, as well as the correlations between the two leading jets are measured in three regions of pT(Z). The measurements are compared with several predictions at leading and next-to-leading orders, interfaced with parton showers. Predictions based on transverse-momentum dependent parton distributions and corresponding parton showers give a good description of the measurement in the regions where multiple parton interactions and higher jet multiplicities are not important. The effects of multiple parton interactions are shown to be important to correctly describe the measured spectra in the low pT(Z) regions.
Tumasyan A, Adam W, Andrejkovic JW, et al., 2023, Measurements of jet multiplicity and jet transverse momentum in multijet events in proton-proton collisions at s=13TeV., Eur Phys J C Part Fields, Vol: 83, ISSN: 1434-6044
Multijet events at large transverse momentum (pT) are measured at s=13TeV using data recorded with the CMS detector at the LHC, corresponding to an integrated luminosity of 36.3fb-1. The multiplicity of jets with pT>50GeV that are produced in association with a high-pT dijet system is measured in various ranges of the pT of the jet with the highest transverse momentum and as a function of the azimuthal angle difference Δϕ1,2 between the two highest pT jets in the dijet system. The differential production cross sections are measured as a function of the transverse momenta of the four highest pT jets. The measurements are compared with leading and next-to-leading order matrix element calculations supplemented with simulations of parton shower, hadronization, and multiparton interactions. In addition, the measurements are compared with next-to-leading order matrix element calculations combined with transverse-momentum dependent parton densities and transverse-momentum dependent parton shower.
Tumasyan A, Adam W, Andrejkovic JW, et al., 2023, A search for decays of the Higgs boson to invisible particles in events with a top-antitop quark pair or a vector boson in proton-proton collisions at s=13TeV., Eur Phys J C Part Fields, Vol: 83, ISSN: 1434-6044
A search for decays to invisible particles of Higgs bosons produced in association with a top-antitop quark pair or a vector boson, which both decay to a fully hadronic final state, has been performed using proton-proton collision data collected at s=13TeV by the CMS experiment at the LHC, corresponding to an integrated luminosity of 138fb-1. The 95% confidence level upper limit set on the branching fraction of the 125GeV Higgs boson to invisible particles, B(H→inv), is 0.54 (0.39 expected), assuming standard model production cross sections. The results of this analysis are combined with previous B(H→inv) searches carried out at s=7, 8, and 13TeV in complementary production modes. The combined upper limit at 95% confidence level on B(H→inv) is 0.15 (0.08 expected).
Tumasyan A, Adam W, Ambrogi F, et al., 2022, Nuclear modification of Y states in pPb collisions at √sNN = 5.02 TeV, Physics Letters B, Vol: 835, ISSN: 0370-2693
Production cross sections of Υ(1S), Υ(2S), and Υ(3S) states decaying into μ+μ− in proton-lead (pPb) collisions are reported using data collected by the CMS experiment at √sNN = 5.02 TeV. A comparison is made with corresponding cross sections obtained with pp data measured at the same collision energy and scaled by the Pb nucleus mass number. The nuclear modification factor for Υ(1S) is found to be RpPb(Υ(1S)) = 0.806±0.024 (stat)±0.059 (syst). Similar results for the excited states indicate a sequentialsuppression pattern, such that RpPb(Υ(1S)) > RpPb(Υ(2S)) > RpPb(Υ(3S)). The suppression of all states is much less pronounced in pPb than in PbPb collisions, and independent of transverse momentum pΥT and center-of-mass rapidity yΥCM of the individual Υ state in the studied range pΥT < 30 GeV/c and |yΥCM| <1.93. Models that incorporate final-state effects of bottomonia in pPb collisions are in better agreement with the data than those which only assume initial-state modifications.
Tumasyan A, Adam W, Andrejkovic JW, et al., 2022, Search for new particles in an extended Higgs sector with four b quarks in the final state at √s=13 TeV, PHYSICS LETTERS B, Vol: 835, ISSN: 0370-2693
Tumasyan A, Adam W, Andrejkovic JW, et al., 2022, Addendum: Measurement and QCD analysis of double-differential inclusive jet cross sections in proton-proton collisions at √s=13 TeV, JOURNAL OF HIGH ENERGY PHYSICS, ISSN: 1029-8479
Tumasyan A, Adam W, Bergauer T, et al., 2022, Measurements of the associated production of a W boson and a charm quark in proton-proton collisions at √<i>s</i>=8TeV, EUROPEAN PHYSICAL JOURNAL C, Vol: 82, ISSN: 1434-6044
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- Citations: 5
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