Персона: Поликарпов, Сергей Михайлович
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Институт ядерной физики и технологий
Цель ИЯФиТ и стратегия развития - создание и развитие научно-образовательного центра мирового уровня в области ядерной физики и технологий, радиационного материаловедения, физики элементарных частиц, астрофизики и космофизики.
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- ПубликацияОткрытый доступSearch for invisible decays of a Higgs boson produced through vector boson fusion in proton-proton collisions at s=13TeV(2019) Sirunyan, A. M.; Tumasyan, A.; Adam, W.; Ambrogi, F.; Chadeeva, M.; Parygin, P.; Philippov, D.; Polikarpov, S.; Popova, E.; Rusinov, V.; Dremin, I.; Matveev, V.; Чадеева, Марина Валентиновна; Поликарпов, Сергей Михайлович; Русинов, Владимир Юрьевич; Матвеев, Виктор Анатольевич© 2019 The Author(s) A search for invisible decays of a Higgs boson is performed using proton-proton collision data collected with the CMS detector at the LHC in 2016 at a center-of-mass energy s=13TeV, corresponding to an integrated luminosity of 35.9fb −1 . The search targets the production of a Higgs boson via vector boson fusion. The data are found to be in agreement with the background contributions from standard model processes. An observed (expected) upper limit of 0.33 (0.25), at 95% confidence level, is placed on the branching fraction of the Higgs boson decay to invisible particles, assuming standard model production rates and a Higgs boson mass of 125.09 GeV. Results from a combination of this analysis and other direct searches for invisible decays of the Higgs boson, performed using data collected at s=7, 8, and 13 TeV, are presented. An observed (expected) upper limit of 0.19 (0.15), at 95% confidence level, is set on the branching fraction of invisible decays of the Higgs boson. The combined limit represents the most stringent bound on the invisible branching fraction of the Higgs boson reported to date. This result is also interpreted in the context of Higgs-portal dark matter models, in which upper bounds are placed on the spin-independent dark-matter-nucleon scattering cross section.
- ПубликацияОткрытый доступSearch for Higgs boson pair production in the γγbb‾ final state in pp collisions at s=13TeV(2019) Sirunyan, A. M.; Tumasyan, A.; Adam, W.; Ambrogi, F.; Chistov, R.; Danilov, M.; Dremin, I.; Parygin, P.; Philippov, D.; Polikarpov, S.; Tarkovskii, E.; Matveev, V.; Чистов, Руслан Николаевич; Данилов, Михаил Владимирович; Поликарпов, Сергей Михайлович; Матвеев, Виктор Анатольевич© 2018 The Author(s) A search is presented for the production of a pair of Higgs bosons, where one decays into two photons and the other one into a bottom quark–antiquark pair. The analysis is performed using proton–proton collision data at s=13TeV recorded in 2016 by the CMS detector at the LHC, corresponding to an integrated luminosity of 35.9fb−1. The results are in agreement with standard model (SM) predictions. In a search for resonant production, upper limits are set on the cross section for new spin-0 or spin-2 particles. For the SM-like nonresonant production hypothesis, the data exclude a product of cross section and branching fraction larger than 2.0fb at 95% confidence level (CL), corresponding to about 24 times the SM prediction. Values of the effective Higgs boson self-coupling κλ are constrained to be within the range −11<κλ<17 at 95% CL, assuming all other Higgs boson couplings are at their SM value. The constraints on κλ are the most restrictive to date.
- ПубликацияОткрытый доступSearch for supersymmetric partners of electrons and muons in proton–proton collisions at s=13TeV(2019) Sirunyan, A. M.; Tumasyan, A.; Adam, W.; Ambrogi, F.; Chadeeva, M.; Parygin, P.; Philippov, D.; Polikarpov, S.; Popova, E.; Rusinov, V.; Matveev, V.; Dremin, I.; Чадеева, Марина Валентиновна; Поликарпов, Сергей Михайлович; Русинов, Владимир Юрьевич; Матвеев, Виктор Анатольевич© 2019 The Author(s) A search for direct production of the supersymmetric (SUSY) partners of electrons or muons is presented in final states with two opposite-charge, same-flavour leptons (electrons and muons), no jets, and large missing transverse momentum. The data sample corresponds to an integrated luminosity of 35.9 fb−1 of proton–proton collisions at s=13TeV, collected with the CMS detector at the LHC in 2016. The search uses the MT2 variable, which generalises the transverse mass for systems with two invisible objects and provides a discrimination against standard model backgrounds containing W bosons. The observed yields are consistent with the expectations from the standard model. The search is interpreted in the context of simplified SUSY models and probes slepton masses up to approximately 290, 400, and 450 GeV, assuming right-handed only, left-handed only, and both right- and left-handed sleptons (mass degenerate selectrons and smuons), and a massless lightest supersymmetric particle. Limits are also set on selectrons and smuons separately. These limits show an improvement on the existing limits of approximately 150 GeV.
- ПубликацияОткрытый доступSearch for heavy Majorana neutrinos in same-sign dilepton channels in proton-proton collisions at √s=13 TeV(2019) Sirunyan, A. M.; Tumasyan, A.; Adam, W.; Ambrogi, F.; Matveev, V.; Chistov, R.; Danilov, M.; Parygin, P.; Philippov, D.; Polikarpov, S.; Tarkovskii, E.; Azarkin, M.; Dremin, I.; Kirakosyan, M.; Матвеев, Виктор Анатольевич; Чистов, Руслан Николаевич; Данилов, Михаил Владимирович; Поликарпов, Сергей Михайлович© 2019, The Author(s). A search is performed for a heavy Majorana neutrino (N), produced in leptonic decay of a W boson propagator and decaying into a W boson and a lepton, with the CMS detector at the LHC. The signature used in this search consists of two same-sign leptons, in any flavor combination of electrons and muons, and at least one jet. The data were collected during 2016 in proton-proton collisions at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 35.9 fb−1. The results are found to be consistent with the expected standard model background. Upper limits are set in the mass range between 20 and 1600 GeV in the context of a Type-I seesaw mechanism, on |VeN|2, |VμN|2, and |VeNVμN *|2/(|VeN|2 + |VμN|2), where VℓN is the matrix element describing the mixing of N with the standard model neutrino of flavor ℓ = e, μ. For N masses between 20 and 1600 GeV, the upper limits on |VℓN|2 range between 2.3 × 10−5 and unity. These are the most restrictive direct limits for heavy Majorana neutrino masses above 430 GeV.[Figure not available: see fulltext.]
- ПубликацияОткрытый доступMeasurements with silicon photomultipliers of dose-rate effects in the radiation damage of plastic scintillator tiles in the CMS hadron endcap calorimeter(2020) Sirunyan, A. M.; Tumasyan, A.; Adam, W.; Ambrogi, F.; Chadeeva, M.; Chistov, R.; Danilov, M.; Parygin, P.; Philippov, D.; Polikarpov, S.; Popova, E.; Rusinov, V.; Tarkovskii, E.; Matveev, V.; Чадеева, Марина Валентиновна; Чистов, Руслан Николаевич; Данилов, Михаил Владимирович; Поликарпов, Сергей Михайлович; Русинов, Владимир Юрьевич; Матвеев, Виктор Анатольевич© 2020 CERN for the benefit of the CMS collaboration..Measurements are presented of the reduction of signal output due to radiation damage for two types of plastic scintillator tiles used in the hadron endcap (HE) calorimeter of the CMS detector. The tiles were exposed to particles produced in proton-proton (pp) collisions at the CERN LHC with a center-of-mass energy of 13 TeV, corresponding to a delivered luminosity of 50 fb-1. The measurements are based on readout channels of the HE that were instrumented with silicon photomultipliers, and are derived using data from several sources: A laser calibration system, a movable radioactive source, as well as hadrons and muons produced in pp collisions. Results from several irradiation campaigns using 60Co sources are also discussed. The damage is presented as a function of dose rate. Within the range of these measurements, for a fixed dose the damage increases with decreasing dose rate.
- ПубликацияОткрытый доступSearch for low-mass resonances decaying into bottom quark-antiquark pairs in proton-proton collisions at s =13 TeV(2019) Sirunyan, A. M.; Tumasyan, A.; Adam, W.; Ambrogi, F.; Matveev, V.; Chadeeva, M.; Parygin, P.; Philippov, D.; Polikarpov, S.; Popova, E.; Rusinov, V.; Dremin, I.; Матвеев, Виктор Анатольевич; Чадеева, Марина Валентиновна; Поликарпов, Сергей Михайлович; Русинов, Владимир Юрьевич© 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 SCOAP3. A search for narrow, low-mass, scalar, and pseudoscalar resonances decaying to bottom quark-antiquark pairs is presented. The search is based on events recorded in s=13 TeV proton-proton collisions with the CMS detector at the LHC, collected in 2016, and corresponding to an integrated luminosity of 35.9 fb-1. The search selects events in which the resonance would be produced with high transverse momentum because of the presence of initial- or final-state radiation. In such events, the decay products of the resonance would be reconstructed as a single large-radius jet with high mass and two-prong substructure. A potential signal would be identified as a narrow excess in the jet invariant mass spectrum. No evidence for such a resonance is observed within the mass range from 50 to 350 GeV, and upper limits at 95% confidence level are set on the product of the cross section and branching fraction to a bottom quark-antiquark pair. These constitute the first constraints from the LHC on exotic bottom quark-antiquark resonances with masses below 325 GeV.
- ПубликацияТолько метаданныеMeasurement of anisotropic flow in XeXe collisions at 5.44 TeV with the CMS experiment(2019) Stojanovic, M.; Sirunyan, A. M.; Tumasyan, A.; Adam, W.; Matveev, V.; Chadeeva, M.; Parygin, P.; Philippov, D.; Polikarpov, S.; Popova, E.; Rusinov, V.; Azarkin, M.; Dremin, I.; Kirakosyan, M.; Матвеев, Виктор Анатольевич; Чадеева, Марина Валентиновна; Поликарпов, Сергей Михайлович; Русинов, Владимир ЮрьевичNew measurements of anisotropic flow in XeXe collisions at a center-of-mass energy of 5.44 TeV per nucleon pair, collected by the CMS experiment at the LHC, are presented. The v(2), v(3) and v(4) Fourier coefficients of the anisotropic azimuthal distribution are obtained employing three different analysis techniques: two-particle correlations, the scalar product method, and multiparticle cumulants, which have different sensitivities to non-flow and flow fluctuation effects. The results are shown as a function of transverse momentum (P-T) for various centrality selections, and compared with corresponding results from PbPb collisions. These new measurements in a smaller nucleus-nucleus system than PbPb provide additional insights into the system-size dependence of the collective flow induced by the dominant collision geometry and its fluctuations. In particular, these results, compared to theoretical predictions and Monte Carlo generators, will provide important details on the system size dependence of the medium response in heavy ion collisions. They also offer a unique opportunity to study the onset of flow from small to large systems.
- ПубликацияТолько метаданныеSearch for lepton-flavor violating decays of the Higgs boson in the μτ and eτ final states in proton-proton collisions at s =13 TeV(2021) Sirunyan, A. M.; Tumasyan, A.; Adam, W.; Andrejkovic, J. W.; Matveev, V.; Bychkova, O.; Chistov, R.; Danilov, M.; Parygin, P.; Polikarpov, S.; Матвеев, Виктор Анатольевич; Чистов, Руслан Николаевич; Данилов, Михаил Владимирович; Поликарпов, Сергей Михайлович© 2021 CERN, for the CMS Collaboration.A search is presented for lepton-flavor violating decays of the Higgs boson to μτ and eτ. The dataset corresponds to an integrated luminosity of 137 fb-1 collected at the LHC in proton-proton collisions at a center-of-mass energy of 13 TeV. No significant excess has been found, and the results are interpreted in terms of upper limits on lepton-flavor violating branching fractions of the Higgs boson. The observed (expected) upper limits on the branching fractions are, respectively, B(H→μτ)<0.15(0.15)% and B(H→eτ)<0.22(0.16)% at 95% confidence level.
- ПубликацияТолько метаданныеSearch for new particles in events with energetic jets and large missing transverse momentum in proton-proton collisions at √s = 13 TeV(2021) Tumasyan, A.; Adam, W.; Andrejkovic, J. W.; Bergauer, T.; Matveev, V.; Bychkova, O.; Chistov, R.; Danilov, M.; Oskin, A.; Polikarpov, S.; Selivanova, D.; Матвеев, Виктор Анатольевич; Чистов, Руслан Николаевич; Данилов, Михаил Владимирович; Поликарпов, Сергей Михайлович© 2021, The Author(s).A search is presented for new particles produced at the LHC in proton-proton collisions at s = 13 TeV, using events with energetic jets and large missing transverse momentum. The analysis is based on a data sample corresponding to an integrated luminosity of 101 fb−1, collected in 2017–2018 with the CMS detector. Machine learning techniques are used to define separate categories for events with narrow jets from initial-state radiation and events with large-radius jets consistent with a hadronic decay of a W or Z boson. A statistical combination is made with an earlier search based on a data sample of 36 fb−1, collected in 2016. No significant excess of events is observed with respect to the standard model background expectation determined from control samples in data. The results are interpreted in terms of limits on the branching fraction of an invisible decay of the Higgs boson, as well as constraints on simplified models of dark matter, on first-generation scalar leptoquarks decaying to quarks and neutrinos, and on models with large extra dimensions. Several of the new limits, specifically for spin-1 dark matter mediators, pseudoscalar mediators, colored mediators, and leptoquarks, are the most restrictive to date. [Figure not available: see fulltext.]
- ПубликацияТолько метаданныеObservation of a New Excited Beauty Strange Baryon Decaying to Ξb- π+π-(2021) Sirunyan, A. M.; Tumasyan, A.; Adam, W.; Andrejkovic, J. W.; Matveev, V.; Chistov, R.; Danilov, M.; Oskin, A.; Parygin, P.; Polikarpov, S.; Матвеев, Виктор Анатольевич; Чистов, Руслан Николаевич; Данилов, Михаил Владимирович; Поликарпов, Сергей Михайлович© 2021 CERN.The Ξb-π+π- invariant mass spectrum is investigated with an event sample of proton-proton collisions at s=13 TeV, collected by the CMS experiment at the LHC in 2016-2018 and corresponding to an integrated luminosity of 140 fb-1. The ground state Ξb- is reconstructed via its decays to J/ψΞ- and J/ψΛK-. A narrow resonance, labeled Ξb(6100)-, is observed at a Ξb-π+π- invariant mass of 6100.3±0.2(stat)±0.1(syst)±0.6(Ξb-) MeV, where the last uncertainty reflects the precision of the Ξb- baryon mass. The upper limit on the Ξb(6100)- natural width is determined to be 1.9 MeV at 95% confidence level. The low Ξb(6100)- signal yield observed in data does not allow a measurement of the quantum numbers of the new state. However, following analogies with the established excited Ξc baryon states, the new Ξb(6100)- resonance and its decay sequence are consistent with the orbitally excited Ξb- baryon, with spin and parity quantum numbers JP=3/2-.