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Journal articleTumasyan A, Adam W, Bergauer T, et al., 2023,
Azimuthal Correlations within Exclusive Dijets with Large Momentum Transfer in Photon-Lead Collisions.
, Phys Rev Lett, Vol: 131The structure of nucleons is multidimensional and depends on the transverse momenta, spatial geometry, and polarization of the constituent partons. Such a structure can be studied using high-energy photons produced in ultraperipheral heavy-ion collisions. The first measurement of the azimuthal angular correlations of exclusively produced events with two jets in photon-lead interactions at large momentum transfer is presented, a process that is considered to be sensitive to the underlying nuclear gluon polarization. This study uses a data sample of ultraperipheral lead-lead collisions at sqrt[s_{NN}]=5.02 TeV, corresponding to an integrated luminosity of 0.38 nb^{-1}, collected with the CMS experiment at the LHC. The measured second harmonic of the correlation between the sum and difference of the two jet transverse momentum vectors is found to be positive, and rising, as the dijet transverse momentum increases. A well-tuned model that has been successful at describing a wide range of proton scattering data from the HERA experiments fails to describe the observed correlations, suggesting the presence of gluon polarization effects.
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Journal articleAaij R, Abdelmotteleb ASW, Beteta CA, et al., 2023,
Test of Lepton Universality in <i>b</i> → <i>sl</i><SUP>+</SUP> <i>l</i><SUP>-</SUP> Decays
, PHYSICAL REVIEW LETTERS, Vol: 131, ISSN: 0031-9007 -
Journal articleAaij R, Abdelmotteleb ASW, Abellan Beteta C, et al., 2023,
Measurement of lepton universality parameters in B+ →k+ℓ+ℓ- and B0 →k∗0ℓ+ℓ- decays
, Physical Review D, Vol: 108, ISSN: 2470-0010A simultaneous analysis of the B+→K+ℓ+ℓ- and B0→K∗0ℓ+ℓ- decays is performed to test muon-electron universality in two ranges of the square of the dilepton invariant mass, q2. The measurement uses a sample of beauty meson decays produced in proton-proton collisions collected with the LHCb detector between 2011 and 2018, corresponding to an integrated luminosity of 9 fb-1. A sequence of multivariate selections and strict particle identification requirements produce a higher signal purity and a better statistical sensitivity per unit luminosity than previous LHCb lepton universality tests using the same decay modes. Residual backgrounds due to misidentified hadronic decays are studied using data and included in the fit model. Each of the four lepton universality measurements reported is either the first in the given q2 interval or supersedes previous LHCb measurements. The results are compatible with the predictions of the Standard Model.
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Journal articleAdam W, Bergauer T, Damanakis K, et al., 2023,
Evaluation of HPK n<sup>+</sup>-p planar pixel sensors for the CMS Phase-2 upgrade
, Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, Vol: 1053, ISSN: 0168-9002To cope with the challenging environment of the planned high luminosity upgrade of the Large Hadron Collider (HL-LHC), scheduled to start operation in 2029, CMS will replace its entire tracking system. The requirements for the tracker are largely determined by the long operation time of 10 years with an instantaneous peak luminosity of up to 7.5 × 1034cm−2s−1 in the ultimate performance scenario. Depending on the radial distance from the interaction point, the silicon sensors will receive a particle fluence corresponding to a non-ionising energy loss of up to Φeq= 3.5 × 1016cm−2. This paper focuses on planar pixel sensor design and qualification up to a fluence of Φeq = 1.4 × 1016cm−2. For the development of appropriate planar pixel sensors an R&D program was initiated, which includes n+-p sensors on 150mm (6”) wafers with an active thickness of 150µm with pixel sizes of 100×25 µm2 and 50×50 µm2 manufactured by Hamamatsu Photonics K.K. (HPK). Single chip modules with ROC4Sens and RD53A readout chips were made. Irradiation with protons and neutrons, as well was an extensive test beam campaign at DESY were carried out. This paper presents the investigation of various assemblies mainly with ROC4Sens readout chips. It demonstrates that multiple designs fulfil the requirements in terms of breakdown voltage, leakage current and efficiency. The single point resolution for 50×50 µm2 pixels is measured as 4.0µm for non-irradiated samples, and 6.3µm after irradiation to Φeq = 7.2 × 1015cm−2.
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Journal articleTumasyan A, Adam W, Andrejkovic JW, et al., 2023,
Constraints on anomalous Higgs boson couplings to vector bosons and fermions from the production of Higgs bosons using the ττ final state
, Physical Review D, Vol: 108, ISSN: 2470-0010A study of anomalous couplings of the Higgs boson to vector bosons and fermions is presented. The data were recorded by the CMS experiment at a center-of-mass energy of pp collisions at the LHC of 13 TeV and correspond to an integrated luminosity of 138 fb - 1 . The study uses Higgs boson candidates produced mainly in gluon fusion or electroweak vector boson fusion at the LHC that subsequently decay to a pair of τ leptons. Matrix-element and machine-learning techniques were employed in a search for anomalous interactions. The results are combined with those from the four-lepton and two-photon decay channels to yield the most stringent constraints on anomalous Higgs boson couplings to date. The pure C P -odd scenario of the Higgs boson coupling to gluons is excluded at 2.4 standard deviations. The results are consistent with the standard model predictions.
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Journal articleTumasyan A, Adam W, Andrejkovic JW, et al., 2023,
Measurement of the electroweak production of Formula Presented in association with two jets in proton-proton collisions at Formula Presented
, Physical Review D, Vol: 108, ISSN: 2470-0010A measurement is presented for the electroweak production of a Formula Presented boson, a photon (Formula Presented), and two jets (j) in proton-proton collisions. The leptonic decay of the Formula Presented boson is selected by requiring one identified electron or muon and large missing transverse momentum. The two jets are required to have large invariant dijet mass and large separation in pseudorapidity. The measurement is performed with the data collected by the CMS detector at a center-of-mass energy of Formula Presented, corresponding to an integrated luminosity of Formula Presented. The cross section for the electroweak Formula Presented production is Formula Presented, whereas the total cross section for Formula Presented production is Formula Presented. Differential cross sections are also measured with the distributions unfolded to the particle level. All results are in agreement with the standard model expectations. Constraints are placed on anomalous quartic gauge couplings (aQGCs) in terms of dimension-8 effective field theory operators. These are the most stringent limits to date on the aQGCs parameters Formula Presented and Formula Presented.
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Journal articleTumasyan A, Adam W, Andrejkovic JW, et al., 2023,
Search for new physics using effective field theory in 13 TeV pp collision events that contain a top quark pair and a boosted Z or Higgs boson
, Physical Review D, Vol: 108, ISSN: 2470-0010A data sample containing top quark pairs ( t t ¯ ) produced in association with a Lorentz-boosted Z or Higgs boson is used to search for signs of new physics using effective field theory. The data correspond to an integrated luminosity of 138 fb - 1 of proton-proton collisions produced at a center-of-mass energy of 13 TeV at the LHC and collected by the CMS experiment. Selected events contain a single lepton and hadronic jets, including two identified with the decay of bottom quarks, plus an additional large-radius jet with high transverse momentum identified as a Z or Higgs boson decaying to a bottom quark pair. Machine learning techniques are employed to discriminate between t t ¯ Z or t t ¯ H events and events from background processes, which are dominated by t t ¯ + jets production. No indications of new physics are observed. The signal strengths of boosted t t ¯ Z and t t ¯ H production are measured, and upper limits are placed on the t t ¯ Z and t t ¯ H differential cross sections as functions of the Z or Higgs boson transverse momentum. The effects of new physics are probed using a framework in which the standard model is considered to be the low-energy effective field theory of a higher energy scale theory. Eight possible dimension-six operators are added to the standard model Lagrangian, and their corresponding coefficients are constrained via fits to the data.
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Journal articleAaij R, Abdelmotteleb ASW, Abellan Beteta C, et al., 2023,
First observation of the B+ → Ds+ Ds- K+ decay
, Physical Review D, Vol: 108, ISSN: 2470-0010The B+→Ds+Ds-K+ decay is observed for the first time using proton-proton collision data collected by the LHCb detector at center-of-mass energies of 7, 8, and 13 TeV, corresponding to an integrated luminosity of 9 fb-1. Its branching fraction relative to that of the B+→D+D-K+ decay is measured to be B(B+→Ds+Ds-K+)B(B+→D+D-K+)=0.525±0.033±0.027±0.034, where the first uncertainty is statistical, the second systematic, and the third is due to the uncertainties on the branching fractions of the Ds±→K∓K±π± and D±→K∓π±π± decays. This measurement fills an experimental gap in the knowledge of the family of Cabibbo-favored b¯→c¯cs¯ transitions and opens the path for unique studies of spectroscopy in future.
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Journal articleAaij R, Abdelmotteleb ASW, Abellan Beteta C, et al., 2023,
Search for K S (L)0 →μ+μ-μ+μ- decays at LHCb
, Physical Review D, Vol: 108, ISSN: 2470-0010A search for KS(L)0→μ+μ-μ+μ- decays is performed using proton-proton collision data collected by the LHCb experiment at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 5.1 fb-1. No evidence for signal is found. The 90% confidence level upper limits are the first set for both decays and are B(KS0→μ+μ-μ+μ-)<5.1×10-12 and B(KL0→μ+μ-μ+μ-)<2.3×10-9.
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Journal articleAcar B, Adamov G, Adloff C, et al., 2023,
Neutron irradiation and electrical characterisation of the first 8" silicon pad sensor prototypes for the CMS calorimeter endcap upgrade
, Journal of Instrumentation, Vol: 18As part of its HL-LHC upgrade program, the CMS collaboration is replacing its existing endcap calorimeters with a high-granularity calorimeter (CE). The new calorimeter is a sampling calorimeter with unprecedented transverse and longitudinal readout for both electromagnetic and hadronic compartments. Due to its compactness, intrinsic time resolution, and radiation hardness, silicon has been chosen as active material for the regions exposed to higher radiation levels. The silicon sensors are fabricated as 20 cm (8") wide hexagonal wafers and are segmented into several hundred pads which are read out individually. As part of the sensor qualification strategy, 8"sensor irradiation with neutrons has been conducted at the Rhode Island Nuclear Science Center (RINSC) and followed by their electrical characterisation in 2020-21. The completion of this important milestone in the CE's R&D program is documented in this paper and it provides detailed account of the associated infrastructure and procedures. The results on the electrical properties of the irradiated CE silicon sensors are presented.
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Journal articleAcar B, Adamov G, Adloff C, et al., 2023,
Performance of the CMS High Granularity Calorimeter prototype to charged pion beams of 20-300 GeV/c
, JOURNAL OF INSTRUMENTATION, Vol: 18, ISSN: 1748-0221 -
Journal articleTumasyan A, Adam W, Andrejkovic JW, et al., 2023,
Search for high-mass exclusive <i>γγ →</i> WW and <i>γγ →</i> ZZ production in proton-proton collisions at √s=13 TeV
, JOURNAL OF HIGH ENERGY PHYSICS, ISSN: 1029-8479 -
Journal articleKotlorz D, Christova E, Leader E, 2023,
Tests of the parametrizations of fragmentation functions using data on inclusive pion and kaon production in unpolarized pp collisions from the STAR collaboration and at the NICA project
, International Journal of Modern Physics A, Vol: 38, ISSN: 0217-751XThe goal of this study is to check which, if any, of the published versions of the pion and kaon fragmentation functions (FFs) is compatible with the STAR data on semi-inclusive pion and kaon production in proton{proton collisions, and on the basis of this analysis to make reliable predictions for the pT spectra of the pions and kaons in inclusive pion and kaon production at the future NICA proton{proton collider. The calculations are carried out in next-to-leading order (NLO) of perturbative quantum chromodynamics (pQCD), using the well-tested CTEQ6 parton distributions. We consider the following pion and kaon FFs DSEHS-14 [D. de Florian, R. Sassot, M. Epele, R. J. Hern andez-Pinto and M. Stratmann, Phys. Rev. D 91, 014035 (2015), 1410.6027], DSEHS-17 [D. de Florian, M. Epele, R. J. Hernandez-Pinto, R. Sassot and M. Stratmann, Phys. Rev. D 95, 094019 (2017), 1702.06353], LSS-15 [E. Leader, A. V. Sidorov and D. B. Stamenov, Phys. Rev. D 93, 074026 (2016), 1506.06381], HKNS-07 [M. Hirai, S. Kumano, T. H. Nagai and K. Sudoh, Phys. Rev. D 75, 094009 (2007), hep-ph/0702250] and AKK-08 [S. Albino, B. A. Kniehl and G. Kramer, Nucl. Phys. B 803, 42 (2008), 0803.2768]. Our analysis shows that within the experimental errors all tested sets of FFs provide a good fit to STAR data at the c.m. energy [Formula presented], and the best ones are both LSS-15 and DSEHS-14 for pions and DSEHS-17 for kaons. From comparison of the LO and NLO results it is clear that the latter fit data much better, specially in the region of small pT. The NLO cross-sections are also less scale-Q2 dependent, where pT =2 Q 2pT, than the LO ones. In order to make predictions for NICA energies, we compare the NLO pQCD results with the existing experimental BES STAR data on semi-inclusive hadron production in the most peripheral Au +Au collisions where the nuclear effects can be neglected. The comparison for lower energy scales, like at NICA, shows that a purely pQCD approach is inadequate and suggests the n
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Journal articleAaij R, Abdelmotteleb ASW, Beteta CA, et al., 2023,
Amplitude analysis of the ?<sub>c</sub><SUP>+</SUP>- pK-p<SUP>+</SUP> decay and ?<sub>c</sub><SUP>+</SUP> baryon polarization measurement in semileptonic beauty hadron decays
, PHYSICAL REVIEW D, Vol: 108, ISSN: 2470-0010 -
Journal articleAaij R, Abdelmotteleb ASW, Beteta CA, et al., 2023,
Search for the baryon- and lepton-number violating decays <i>B</i><SUP>0</SUP> → <i>p</i>μ<SUP>-</SUP> and <i>B<sub>s</sub></i><SUP>0</SUP> → <i>p</i>μ<SUP>-</SUP>
, PHYSICAL REVIEW D, Vol: 108, ISSN: 2470-0010 -
Journal articleAalbers J, Akerib DS, Akerlof CW, et al., 2023,
First Dark Matter Search Results from the LUX-ZEPLIN (LZ) Experiment
, PHYSICAL REVIEW LETTERS, Vol: 131, ISSN: 0031-9007- Author Web Link
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- Citations: 5
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Journal articleAaij R, Abdelmotteleb ASW, Abellan Beteta C, et al., 2023,
Search for Rare Decays of D^{0} Mesons into Two Muons.
, Phys Rev Lett, Vol: 131A search for the very rare D^{0}→μ^{+}μ^{-} decay is performed using data collected by the LHCb experiment in proton-proton collisions at sqrt[s]=7, 8, and 13 TeV, corresponding to an integrated luminosity of 9 fb^{-1}. The search is optimized for D^{0} mesons from D^{*+}→D^{0}π^{+} decays but is also sensitive to D^{0} mesons from other sources. No evidence for an excess of events over the expected background is observed. An upper limit on the branching fraction of this decay is set at B(D^{0}→μ^{+}μ^{-})<3.1×10^{-9} at a 90% C.L. This represents the world's most stringent limit, constraining models of physics beyond the standard model.
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Journal articleTumasyan A, Adam W, Andrejkovic JW, et al., 2023,
Search for Higgs Boson and Observation of Z Boson through Their Decay into a Charm Quark-Antiquark Pair in Boosted Topologies in Proton-Proton Collisions at sqrt[s]=13 TeV.
, Phys Rev Lett, Vol: 131A search for the standard model (SM) Higgs boson (H) produced with transverse momentum (p_{T}) greater than 450 GeV and decaying to a charm quark-antiquark (cc[over ¯]) pair is presented. The search is performed using proton-proton collision data collected at sqrt[s]=13 TeV by the CMS experiment at the LHC, corresponding to an integrated luminosity of 138 fb^{-1}. Boosted H→cc[over ¯] decay products are reconstructed as a single large-radius jet and identified using a deep neural network charm tagging technique. The method is validated by measuring the Z→cc[over ¯] decay process, which is observed in association with jets at high p_{T} for the first time with a signal strength of 1.00_{-0.14}^{+0.17}(syst)±0.08(theo)±0.06(stat), defined as the ratio of the observed process rate to the SM expectation. The observed (expected) upper limit on σ(H)B(H→cc[over ¯]) is set at 47 (39) times the SM prediction at 95% confidence level.
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Journal articleTumasyan A, Adam W, Andrejkovic JW, et al., 2023,
Search for Nonresonant Pair Production of Highly Energetic Higgs Bosons Decaying to Bottom Quarks.
, Phys Rev Lett, Vol: 131A search for nonresonant Higgs boson (H) pair production via gluon and vector boson (V) fusion is performed in the four-bottom-quark final state, using proton-proton collision data at 13 TeV corresponding to 138 fb^{-1} collected by the CMS experiment at the LHC. The analysis targets Lorentz-boosted H pairs identified using a graph neural network. It constrains the strengths relative to the standard model of the H self-coupling and the quartic VVHH couplings, κ_{2V}, excluding κ_{2V}=0 for the first time, with a significance of 6.3 standard deviations when other H couplings are fixed to their standard model values.
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Journal articleAaij R, Abdelmotteleb ASW, Beteta CA, et al., 2023,
A study of <i>CP</i> violation in the decays <i>B</i><SUP>±</SUP> → [<i>K</i><SUP>+</SUP><i>K</i><SUP>-</SUP>π<SUP>+</SUP>π<SUP>-</SUP>]<i><sub>D</sub>h</i><SUP>±</SUP> (<i>h</i> = <i>K</i>, π) and <i>B</i><SUP>±</SUP> → [π<SUP>+</SUP>π<SUP>-</SUP>π<SUP>+</SUP>π<SUP>-</SUP>]<i><sub>D</sub>h</i><SUP>±</SUP> (vol 83, 547, 2023)
, EUROPEAN PHYSICAL JOURNAL C, Vol: 83, ISSN: 1434-6044 -
Journal articleTumasyan A, Adam W, Andrejkovic JW, et al., 2023,
Measurement of the cross section of top quark-antiquark pair production in association with a W boson in proton-proton collisions at √s=13 TeV
, JOURNAL OF HIGH ENERGY PHYSICS, ISSN: 1029-8479 -
Journal articleAaij R, Abdelmotteleb ASW, Beteta CA, et al., 2023,
Observation of sizeable ? contribution to?<i>c1</i>(3872) ? p<i>+ p- J=?</i> decays
, PHYSICAL REVIEW D, Vol: 108, ISSN: 2470-0010 -
Journal articleAaij R, Abdelmotteleb ASW, Beteta CA, et al., 2023,
First Observation of a Doubly Charged Tetraquark and Its Neutral Partner
, PHYSICAL REVIEW LETTERS, Vol: 131, ISSN: 0031-9007- Author Web Link
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- Citations: 1
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Journal articleAad G, Abbott B, Abbott DC, et al., 2023,
Combination of inclusive top-quark pair production cross-section measurements using ATLAS and CMS data at √s=7 and 8 TeV
, JOURNAL OF HIGH ENERGY PHYSICS, ISSN: 1029-8479 -
Journal articleTumasyan A, Adam W, Andrejkovic JW, et al., 2023,
Search for long-lived particles using out-of-time trackless jets in proton-proton collisions at √<i>s</i>=13 TeV
, JOURNAL OF HIGH ENERGY PHYSICS, ISSN: 1029-8479 -
Journal articleAaij R, Abdelmotteleb ASW, Beteta CA, et al., 2023,
Study of the B<SUP>-</SUP> → Λ<sub>c</sub><SUP>+</SUP>(Λ)over-bar<sub>c</sub><SUP>-</SUP><i>K</i><SUP>-</SUP> decay
, PHYSICAL REVIEW D, Vol: 108, ISSN: 2470-0010 -
Journal articleAaij R, Abdelmotteleb ASW, Beteta CA, et al., 2023,
Search for D* (2007)<SUP>0</SUP> → μ<SUP>+</SUP> μ<SUP>-</SUP> in B<SUP>-</SUP> → π<SUP>-</SUP> μ<SUP>+</SUP> μ<SUP>-</SUP> decays
, EUROPEAN PHYSICAL JOURNAL C, Vol: 83, ISSN: 1434-6044 -
Journal articleTumasyan A, Adam W, Andrejkovic JW, et al., 2023,
Measurements of the Higgs boson production cross section and couplings in the W boson pair decay channel in proton-proton collisions at √s=13TeV
, EUROPEAN PHYSICAL JOURNAL C, Vol: 83, ISSN: 1434-6044 -
Journal articleAaij R, Abdelmotteleb ASW, Beteta CA, et al., 2023,
J/ψ and D<SUP>0</SUP> production in √s<sub>NN</sub>=68.5GeV PbNe collisions
, EUROPEAN PHYSICAL JOURNAL C, Vol: 83, ISSN: 1434-6044 -
Journal articleAaij R, Abdelmotteleb ASW, Beteta CA, et al., 2023,
Nuclear Modification Factor of Neutral Pions in the Forward and Backward Regions in <i>p</i>-Pb Collisions
, PHYSICAL REVIEW LETTERS, Vol: 131, ISSN: 0031-9007
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