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Journal articleKarikar A, Ahmed A, Das K, et al., 2023,
Magnetic and magnetocaloric properties of polycrystalline Pr<inf>1−x</inf>Ca<inf>x</inf>MnO<inf>3</inf> (x ∼ 0.85, 0.90, 0.95) compounds: Emergence of large inverse and conventional magnetocaloric effects
, Journal of Magnetism and Magnetic Materials, Vol: 587, ISSN: 0304-8853Magnetic and magnetocaloric effect have been investigated for the electron doped polycrystalline Pr1−xCaxMnO3 (x ∼ 0.85, 0.90, 0.95) compounds. The experimental outcomes indicate that the nature of the ground state is very much sensitive with the doping concentration. Pr0.15Ca0.85MnO3 compound exhibits antiferromagnetic ground state. In contrast to that ferromagnetic nature was found for the Pr0.10Ca0.90MnO3 and Pr0.05Ca0.95MnO3 compounds. Although, for x∼0.90 ferromagnetic phase was stable. However for x∼ 0.95, the ferromagnetic state is quite unstable. Additionally for the doping concentration x∼ 0.95, the anomalous nature was found in temperature dependent coercivity. Magnetocaloric effect study indicate that antiferromagnetic Pr0.15Ca0.85MnO3 compound exhibits large inverse magnetocaloric effect (10.5 J/kg-K at H = 70 kOe magnetic field). On the other hand, ferromagnetic Pr0.10Ca0.90MnO3 and Pr0.05Ca0.95MnO3 compounds show conventional magnetocaloric effect. The magnetocaloric entropy change for x∼0.90 compound is significantly large (7.5 J/kg-K at H = 70 kOe magnetic field) and comparable with the other reported magnetic refrigerant materials. Universal master curve for magnetic entropy change have been constructed for all the materials having inverse and conventional magnetocaloric effect by proper scaling of temperature axis.
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Journal articleHayrapetyan A, Tumasyan A, Adam W, et al., 2023,
Observation of four top quark production in proton-proton collisions at <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.svg"><mml:msqrt><mml:mrow><mml:mi>s</mml:mi></mml:mrow></mml:msqrt><mml:mo linebreak="goodbreak" linebreakstyle="after">=</mml:mo><mml:mn>13</mml:mn><mml:mspace width="0.2em" /><mml:mtext>TeV</mml:mtext></mml:math>
, Physics Letters B, Vol: 847, Pages: 138290-138290, ISSN: 0370-2693 -
Journal articleTumasyan A, Adam W, Ambrogi F, et al., 2023,
First measurement of the forward rapidity gap distribution in <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mi>p</mml:mi><mml:mi>Pb</mml:mi></mml:mrow></mml:math> collisions at <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msqrt><mml:mrow><mml:msub><mml:mrow><mml:mi>s</mml:mi></mml:mrow><mml:mrow><mml:mi>NN</mml:mi></mml:mrow></mml:msub></mml:mrow></mml:msqrt><mml:mo>=</mml:mo><mml:mn>8.16</mml:mn><mml:mtext> </mml:mtext><mml:mtext> </mml:mtext><mml:mi>TeV</mml:mi></mml:mrow></mml:math>
, Physical Review D, Vol: 108, ISSN: 2470-0010 -
Journal articleTumasyan A, Adam W, Andrejkovic JW, et al., 2023,
Measurement of the tt¯ charge asymmetry in events with highly Lorentz-boosted top quarks in pp collisions at s=13 TeV
, Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics, Vol: 846, ISSN: 0370-2693The measurement of the charge asymmetry in top quark pair events with highly Lorentz-boosted top quarks decaying to a single lepton and jets is presented. The analysis is performed using proton-proton collisions at s=13TeV with the CMS detector at the LHC and corresponding to an integrated luminosity of 138 fb−1. The selection is optimized for top quarks produced with large Lorentz boosts, resulting in nonisolated leptons and overlapping jets. The top quark charge asymmetry is measured for events with a tt¯ invariant mass larger than 750 GeV and corrected for detector and acceptance effects using a binned maximum likelihood fit. The measured top quark charge asymmetry of (0.42−0.69+0.64)% is in good agreement with the standard model prediction at next-to-next-to-leading order in quantum chromodynamic perturbation theory with next-to-leading-order electroweak corrections. The result is also presented for two invariant mass ranges, 750–900 and >900GeV.
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Journal articleTumasyan A, Adam W, Andrejkovic JW, et al., 2023,
Search for the Higgs boson decay to a pair of electrons in proton-proton collisions at s=13TeV
, Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics, Vol: 846, ISSN: 0370-2693A search is presented for the Higgs boson decay to a pair of electrons ([Formula presented]) in proton-proton collisions at s=13TeV. The data set was collected with the CMS experiment at the LHC between 2016 and 2018, corresponding to an integrated luminosity of 138fb−1. The analysis uses event categories targeting Higgs boson production via gluon fusion and vector boson fusion. The observed upper limit on the Higgs boson branching fraction to an electron pair is 3.0×10−4 (3.0×10−4 expected) at the 95% confidence level, which is the most stringent limit on this branching fraction to date.
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Journal articleTumasyan A, Adam W, Andrejkovic JW, et al., 2023,
Search for pair-produced vector-like leptons in final states with third-generation leptons and at least three b quark jets in proton-proton collisions at s=13TeV
, Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics, Vol: 846, ISSN: 0370-2693The first search is presented for vector-like leptons (VLLs) in the context of the “4321 model”, an ultraviolet-complete model with the potential to explain existing B physics measurements that are in tension with standard model predictions. The analyzed data, corresponding to an integrated luminosity of 96.5fb−1, were recorded in 2017 and 2018 with the CMS detector at the LHC in proton-proton collisions at s=13TeV. Final states with ≥3 b -tagged jets and two third-generation leptons (ττ, τντ, or ντντ) are considered. Upper limits are derived on the VLL production cross section in the VLL mass range 500–1050 GeV. The maximum likelihood fit prefers the presence of signal at the level of 2.8 standard deviations, for a representative VLL mass point of 600 GeV. As a consequence, the observed upper limits are approximately double the expected limits.
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Journal articleTumasyan A, Adam W, Andrejkovic JW, et al., 2023,
Performance of the local reconstruction algorithms for the CMS hadron calorimeter with Run 2 data
, Journal of Instrumentation, Vol: 18, Pages: P11017-P11017<jats:title>Abstract</jats:title> <jats:p>A description is presented of the algorithms used to reconstruct energy deposited in the CMS hadron calorimeter during Run 2 (2015–2018) of the LHC. During Run 2, the characteristic bunch-crossing spacing for proton-proton collisions was 25 ns, which resulted in overlapping signals from adjacent crossings. The energy corresponding to a particular bunch crossing of interest is estimated using the known pulse shapes of energy depositions in the calorimeter, which are measured as functions of both energy and time. A variety of algorithms were developed to mitigate the effects of adjacent bunch crossings on local energy reconstruction in the hadron calorimeter in Run 2, and their performance is compared.</jats:p>
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Journal articleScandale W, Cerutti F, Esposito LS, et al., 2023,
Beam merging assisted by a bent crystal
, European Physical Journal Plus, Vol: 138Bunch merging is a well-established technique to increase the intensity of synchrotrons and the luminosity of circular colliders. We suggest to exploit a combination of channeling, volume reflection and amorphous interactions in a bent crystal for beam merging in a transfer line. Two beams converging into the bent crystal along special directions should emerge in almost parallel directions. A merging scenario is discussed, and data collected by the UA9 Collaboration are reprocessed to prove its feasibility. Comparison with magnetic stacking, which is a similar process, is presented.
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Journal articleAaij R, Abdelmotteleb ASW, Abellan Beteta C, et al., 2023,
Observation of New Baryons in the Ξ_{b}^{-}π^{+}π^{-} and Ξ_{b}^{0}π^{+}π^{-} Systems.
, Phys Rev Lett, Vol: 131The first observation and study of two new baryonic structures in the final state Ξ_{b}^{0}π^{+}π^{-} and the confirmation of the Ξ_{b}(6100)^{-} state in the Ξ_{b}^{-}π^{+}π^{-} decay mode are reported using proton-proton collision data collected by the LHCb experiment, corresponding to an integrated luminosity of 9 fb^{-1}. In addition, the properties of the known Ξ_{b}^{*0}, Ξ_{b}^{'-} and Ξ_{b}^{*-} resonances are measured with improved precision. The new decay mode of the Ξ_{b}^{0} baryon to the Ξ_{c}^{+} π^{-} π^{+} π^{-} final state is observed and exploited for the first time in these measurements.
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Journal articleAaij R, Abdelmotteleb ASW, Abellan Beteta C, et al., 2023,
Precision Measurement of CP Violation in the Penguin-Mediated Decay B_{s}^{0}→ϕϕ.
, Phys Rev Lett, Vol: 131A flavor-tagged time-dependent angular analysis of the decay B_{s}^{0}→ϕϕ is performed using pp collision data collected by the LHCb experiment at the center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 6 fb^{-1}. The CP-violating phase and direct CP-violation parameter are measured to be ϕ_{s}^{ss[over ¯]s}=-0.042±0.075±0.009 rad and |λ|=1.004±0.030±0.009, respectively, assuming the same values for all polarization states of the ϕϕ system. In these results, the first uncertainties are statistical and the second systematic. These parameters are also determined separately for each polarization state, showing no evidence for polarization dependence. The results are combined with previous LHCb measurements using pp collisions at center-of-mass energies of 7 and 8 TeV, yielding ϕ_{s}^{ss[over ¯]s}=-0.074±0.069 rad and |λ|=1.009±0.030. This is the most precise study of time-dependent CP violation in a penguin-dominated B meson decay. The results are consistent with CP symmetry and with the standard model predictions.
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Journal articleTumasyan A, Adam W, Andrejkovic JW, et al., 2023,
Measurements of the azimuthal anisotropy of prompt and nonprompt charmonia in PbPb collisions at $$ \sqrt{s_{\textrm{NN}}} $$ = 5.02 TeV
, Journal of High Energy Physics, Vol: 2023<jats:title>A<jats:sc>bstract</jats:sc> </jats:title><jats:p>The second-order (<jats:italic>v</jats:italic><jats:sub>2</jats:sub>) and third-order (<jats:italic>v</jats:italic><jats:sub>3</jats:sub>) Fourier coefficients describing the azimuthal anisotropy of prompt and nonprompt (from b-hadron decays) J<jats:italic>/</jats:italic>ψ, as well as prompt ψ(2S) mesons are measured in lead-lead collisions at a center-of-mass energy per nucleon pair of <jats:inline-formula><jats:alternatives><jats:tex-math>$$ \sqrt{s_{\textrm{NN}}} $$</jats:tex-math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msqrt> <mml:msub> <mml:mi>s</mml:mi> <mml:mi>NN</mml:mi> </mml:msub> </mml:msqrt> </mml:math></jats:alternatives></jats:inline-formula> = 5<jats:italic>.</jats:italic>02 TeV. The analysis uses a data set corresponding to an integrated luminosity of 1.61 nb<jats:sup><jats:italic>−</jats:italic>1</jats:sup> recorded with the CMS detector. The J<jats:italic>/</jats:italic>ψ and ψ(2S) mesons are reconstructed using their dimuon decay channel. The <jats:italic>v</jats:italic><jats:sub>2</jats:sub> and <jats:italic>v</jats:italic><jats:sub>3</jats:sub> coefficients are extracted using the scalar product method and studied as functions of meson transverse momentum and collision centrality. The measured <jats:italic>v</jats:italic><jats:sub>2</jats:sub> values for prompt J<jats:italic>/</jats:italic>ψ mesons are found to be larger than those for nonprompt J<jats:italic>/<
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Journal articleTumasyan A, Adam W, Andrejkovic JW, et al., 2023,
Observation of τ Lepton Pair Production in Ultraperipheral Pb-Pb Collisions at sqrt[s_{NN}]=5.02 TeV.
, Phys Rev Lett, Vol: 131We present an observation of photon-photon production of τ lepton pairs in ultraperipheral lead-lead collisions. The measurement is based on a data sample with an integrated luminosity of 404 μb^{-1} collected by the CMS experiment at a center-of-mass energy per nucleon pair of sqrt[s_{NN}]=5.02 TeV. The γγ→τ^{+}τ^{-} process is observed for τ^{+}τ^{-} events with a muon and three charged hadrons in the final state. The measured fiducial cross section is σ(γγ→τ^{+}τ^{-})=4.8±0.6(stat)±0.5(syst) μb, where the second (third) term corresponds to the statistical (systematic) uncertainty in σ(γγ→τ^{+}τ^{-}) in agreement with leading-order QED predictions. Using σ(γγ→τ^{+}τ^{-}), we estimate a model-dependent value of the anomalous magnetic moment of the τ lepton of a_{τ}=0.001_{-0.089}^{+0.055}.
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Journal articleAaij R, Abdelmotteleb ASW, Abellan Beteta C, et al., 2023,
Measurement of the Λ_{b}^{0}→Λ(1520)μ^{+}μ^{-} Differential Branching Fraction.
, Phys Rev Lett, Vol: 131The branching fraction of the rare decay Λ_{b}^{0}→Λ(1520)μ^{+}μ^{-} is measured for the first time, in the squared dimuon mass intervals q^{2}, excluding the J/ψ and ψ(2S) regions. The data sample analyzed was collected by the LHCb experiment at center-of-mass energies of 7, 8, and 13 TeV, corresponding to a total integrated luminosity of 9 fb^{-1}. The result in the highest q^{2} interval, q^{2}>15.0 GeV^{2}/c^{4}, where theoretical predictions have the smallest model dependence, agrees with the predictions.
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Journal articleHayrapetyan A, Tumasyan A, Adam W, et al., 2023,
Search for the lepton-flavor violating decay of the Higgs boson and additional Higgs bosons in the <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mi>e</mml:mi><mml:mi>μ</mml:mi></mml:mrow></mml:math> final state in proton-proton collisions at <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msqrt><mml:mi>s</mml:mi></mml:msqrt><mml:mo>=</mml:mo><mml:mn>13</mml:mn><mml:mtext> </mml:mtext><mml:mtext> </mml:mtext><mml:mi>TeV</mml:mi></mml:math>
, Physical Review D, Vol: 108, ISSN: 2470-0010 -
Journal articleHayrapetyan A, Tumasyan A, Adam W, et al., 2023,
Search for a high-mass dimuon resonance produced in association with b quark jets at $$ \sqrt{s} $$ = 13 TeV
, Journal of High Energy Physics, Vol: 2023<jats:title>A<jats:sc>bstract</jats:sc> </jats:title><jats:p>A search for high-mass dimuon resonance production in association with one or more b quark jets is presented. The study uses proton-proton collision data collected with the CMS detector at the LHC corresponding to an integrated luminosity of 138 fb<jats:sup><jats:italic>−</jats:italic>1</jats:sup> at a center-of-mass energy of 13 TeV. Model-independent limits are derived on the number of signal events with exactly one or more than one b quark jet. Results are also interpreted in a lepton-flavor-universal model with Z′ boson couplings to a bb quark pair (<jats:italic>g</jats:italic><jats:sub>b</jats:sub>), an sb quark pair (<jats:italic>g</jats:italic><jats:sub>b</jats:sub><jats:italic>δ</jats:italic><jats:sub>bs</jats:sub>), and any same-flavor charged lepton (<jats:italic>g</jats:italic><jats:sub><jats:italic>ℓ</jats:italic></jats:sub>) or neutrino pair (<jats:italic>g</jats:italic><jats:sub><jats:italic>ν</jats:italic></jats:sub>), with <jats:italic>|g</jats:italic><jats:sub><jats:italic>ν</jats:italic></jats:sub><jats:italic>|</jats:italic> = <jats:italic>|g</jats:italic><jats:sub><jats:italic>ℓ</jats:italic></jats:sub><jats:italic>|</jats:italic>. For a Z′ boson with a mass <jats:inline-formula><jats:alternatives><jats:tex-math>$$ {m}_{{\textrm{Z}}^{\prime }} $$</jats:tex-math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mi>m</mml:mi> <mml:msup> <mml:mi>Z</mml:mi> &l
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Journal articleHayrapetyan A, Tumasyan A, Adam W, et al., 2023,
Search for new physics in multijet events with at least one photon and large missing transverse momentum in proton-proton collisions at 13 TeV
, Journal of High Energy Physics, Vol: 2023<jats:title>A<jats:sc>bstract</jats:sc> </jats:title><jats:p>A search for new physics in final states consisting of at least one photon, multiple jets, and large missing transverse momentum is presented, using proton-proton collision events at a center-of-mass energy of 13 TeV. The data correspond to an integrated luminosity of 137 fb<jats:sup><jats:italic>−</jats:italic>1</jats:sup>, recorded by the CMS experiment at the CERN LHC from 2016 to 2018. The events are divided into mutually exclusive bins characterized by the missing transverse momentum, the number of jets, the number of b-tagged jets, and jets consistent with the presence of hadronically decaying W, Z, or Higgs bosons. The observed data are found to be consistent with the prediction from standard model processes. The results are interpreted in the context of simplified models of pair production of supersymmetric particles via strong and electroweak interactions. Depending on the details of the signal models, gluinos and squarks of masses up to 2.35 and 1.43 TeV, respectively, and electroweakinos of masses up to 1.23 TeV are excluded at 95% confidence level.</jats:p>
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Journal articleAalbers J, Akerib DS, Al Musalhi AK, et al., 2023,
Search for new physics in low-energy electron recoils from the first LZ exposure
, Physical Review D, Vol: 108, ISSN: 2470-0010The LUX-ZEPLIN (LZ) experiment is a dark matter detector centered on a dual-phase xenon time projection chamber. We report searches for new physics appearing through few-keV-scale electron recoils, using the experiment's first exposure of 60 live days and a fiducial mass of 5.5 t. The data are found to be consistent with a background-only hypothesis, and limits are set on models for new physics including solar axion electron coupling, solar neutrino magnetic moment and millicharge, and electron couplings to galactic axionlike particles and hidden photons. Similar limits are set on weakly interacting massive particle (WIMP) dark matter producing signals through ionized atomic states from the Migdal effect.
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Journal articleAaij R, Abdelmotteleb ASW, Abellan Beteta C, et al., 2023,
Observation of New Ω_{c}^{0} States Decaying to the Ξ_{c}^{+}K^{-} Final State.
, Phys Rev Lett, Vol: 131Two new excited states, Ω_{c}(3185)^{0} and Ω_{c}(3327)^{0}, are observed in the Ξ_{c}^{+}K^{-} invariant-mass spectrum using proton-proton collision data collected by the LHCb experiment, corresponding to an integrated luminosity of 9 fb^{-1}. Five previously observed excited Ω_{c}^{0} states are confirmed, namely Ω_{c}(3000)^{0}, Ω_{c}(3050)^{0}, Ω_{c}(3065)^{0}, Ω_{c}(3090)^{0}, and Ω_{c}(3119)^{0}. The masses and widths of these seven states are measured with the highest precision to date.
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Journal articleAaij R, Abdelmotteleb ASW, Abellan Beteta C, et al., 2023,
Evidence of a J/ψK_{S}^{0} Structure in B^{0}→J/ψϕK_{S}^{0} Decays.
, Phys Rev Lett, Vol: 131An amplitude analysis of B^{0}→J/ψϕK_{S}^{0} decays is performed using proton-proton collision data, corresponding to an integrated luminosity of 9 fb^{-1}, collected with the LHCb detector at center-of-mass energies of 7, 8, and 13 TeV. Evidence with a significance of 4.0 standard deviations of a structure in the J/ψK_{S}^{0} system, named T_{ψs1}^{θ}(4000)^{0}, is seen, with its mass and width measured to be 3991_{-10}^{+12} _{-17}^{+9} MeV/c^{2} and 105_{-25}^{+29} _{-23}^{+17} MeV, respectively, where the first uncertainty is statistical and the second systematic. The T_{ψs1}^{θ}(4000)^{0} state is likely to be the isospin partner of the T_{ψs1}^{θ}(4000)^{+} state, previously observed in the J/ψK^{+} system of the B^{+}→J/ψϕK^{+} decay. When isospin symmetry for the charged and neutral T_{ψs1}^{θ}(4000) states is assumed, the signal significance increases to 5.4 standard deviations.
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Journal articleTumasyan A, Adam W, Andrejkovic JW, et al., 2023,
Search for supersymmetry in final states with a single electron or muon using angular correlations and heavy-object identification in proton-proton collisions at $$ \sqrt{s} $$ = 13 TeV
, Journal of High Energy Physics, Vol: 2023<jats:title>A<jats:sc>bstract</jats:sc> </jats:title><jats:p>A search for supersymmetry is presented in events with a single charged lepton, electron or muon, and multiple hadronic jets. The data correspond to an integrated luminosity of 138 fb<jats:sup><jats:italic>−</jats:italic>1</jats:sup> of proton-proton collisions at a center-of-mass energy of 13 TeV, recorded by the CMS experiment at the CERN LHC. The search targets gluino pair production, where the gluinos decay into final states with the lightest supersymmetric particle (LSP) and either a top quark-antiquark (<jats:inline-formula><jats:alternatives><jats:tex-math>$$ \textrm{t}\overline{\textrm{t}} $$</jats:tex-math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>t</mml:mi> <mml:mover> <mml:mi>t</mml:mi> <mml:mo>¯</mml:mo> </mml:mover> </mml:math></jats:alternatives></jats:inline-formula>) pair, or a light-flavor quark-antiquark (<jats:inline-formula><jats:alternatives><jats:tex-math>$$ \textrm{q}\overline{\textrm{q}} $$</jats:tex-math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>q</mml:mi> <mml:mover> <mml:mi>q</mml:mi> <mml:mo>¯</mml:mo> </mml:mover> </mml:math></jats:alternatives></jats:inline-formula>) pair and a virtual or on-shell W boson. The main backgrounds, <jats:inline-formula><jats:alternatives><jats:tex-math>$$ \textrm{t}\overline{\textrm{t}} $$</jats:tex-math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML">
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Journal articleTumasyan A, Adam W, Andrejkovic JW, et al., 2023,
Measurement of the Dependence of the Hadron Production Fraction Ratios f_{s}/f_{u} and f_{d}/f_{u} on B Meson Kinematic Variables in Proton-Proton Collisions at sqrt[s]=13 TeV.
, Phys Rev Lett, Vol: 131The dependence of the ratio between the B_{s}^{0} and B^{+} hadron production fractions, f_{s}/f_{u}, on the transverse momentum (p_{T}) and rapidity of the B mesons is studied using the decay channels B_{s}^{0}→J/ψϕ and B^{+}→J/ψK^{+}. The analysis uses a data sample of proton-proton collisions at a center-of-mass energy of 13 TeV, collected by the CMS experiment in 2018 and corresponding to an integrated luminosity of 61.6 fb^{-1}. The f_{s}/f_{u} ratio is observed to depend on the B p_{T} and to be consistent with becoming asymptotically constant at large p_{T}. No rapidity dependence is observed. The ratio of the B^{0} to B^{+} meson production fractions, f_{d}/f_{u}, is also measured, for the first time in proton-proton collisions, using the B^{0}→J/ψK^{*0} decay channel. The result is found to be within 1 standard deviation of unity and independent of p_{T} and rapidity, as expected from isospin invariance.
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Journal articleAaij R, Abdelmotteleb ASW, Abellan Beteta C, et al., 2023,
Measurement of the Ratios of Branching Fractions R(D^{*}) and R(D^{0}).
, Phys Rev Lett, Vol: 131The ratios of branching fractions R(D^{*})≡B(B[over ¯]→D^{*}τ^{-}ν[over ¯]_{τ})/B(B[over ¯]→D^{*}μ^{-}ν[over ¯]_{μ}) and R(D^{0})≡B(B^{-}→D^{0}τ^{-}ν[over ¯]_{τ})/B(B^{-}→D^{0}μ^{-}ν[over ¯]_{μ}) are measured, assuming isospin symmetry, using a sample of proton-proton collision data corresponding to 3.0 fb^{-1} of integrated luminosity recorded by the LHCb experiment during 2011 and 2012. The tau lepton is identified in the decay mode τ^{-}→μ^{-}ν_{τ}ν[over ¯]_{μ}. The measured values are R(D^{*})=0.281±0.018±0.024 and R(D^{0})=0.441±0.060±0.066, where the first uncertainty is statistical and the second is systematic. The correlation between these measurements is ρ=-0.43. The results are consistent with the current average of these quantities and are at a combined 1.9 standard deviations from the predictions based on lepton flavor universality in the standard model.
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Journal articleTumasyan A, Adam W, Andrejkovic JW, et al., 2023,
Search for new heavy resonances decaying to WW, WZ, ZZ, WH, or ZH boson pairs in the all-jets final state in proton-proton collisions at s=13TeV
, Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics, Vol: 844, ISSN: 0370-2693A search for new heavy resonances decaying to WW, WZ, ZZ, WH, or ZH boson pairs in the all-jets final state is presented. The analysis is based on proton-proton collision data recorded by the CMS detector in 2016–2018 at a centre-of-mass energy of 13 TeV at the CERN LHC, corresponding to an integrated luminosity of 138 fb−1. The search is sensitive to resonances with masses between 1.3 and 6TeV, decaying to bosons that are highly Lorentz-boosted such that each of the bosons forms a single large-radius jet. Machine learning techniques are employed to identify such jets. No significant excess over the estimated standard model background is observed. A maximum local significance of 3.6 standard deviations, corresponding to a global significance of 2.3 standard deviations, is observed at masses of 2.1 and 2.9 TeV. In a heavy vector triplet model, spin-1 Z′ and W′ resonances with masses below 4.8TeV are excluded at the 95% confidence level (CL). These limits are the most stringent to date. In a bulk graviton model, spin-2 gravitons and spin-0 radions with masses below 1.4 and 2.7TeV, respectively, are excluded at 95% CL. Production of heavy resonances through vector boson fusion is constrained with upper cross section limits at 95% CL as low as 0.1 fb.
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Journal articleTumasyan A, Adam W, Bergauer T, et al., 2023,
Two-particle azimuthal correlations in γp interactions using pPb collisions at s<inf><inf>NN</inf></inf>=8.16TeV
, Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics, Vol: 844, ISSN: 0370-2693The first measurements of the Fourier coefficients (VnΔ) of the azimuthal distributions of charged hadrons emitted from photon-proton (γp) interactions are presented. The data are extracted from 68.8 nb−1 of ultra-peripheral proton-lead (pPb) collisions at sNN=8.16TeV using the CMS detector. The high energy lead ions produce a flux of photons that can interact with the oncoming proton. This γp system provides a set of unique initial conditions with multiplicity lower than in photon-lead collisions but comparable to recent electron-positron and electron-proton data. The VnΔ coefficients are presented in ranges of event multiplicity and transverse momentum (pT) and are compared to corresponding hadronic minimum bias pPb results. For a given multiplicity range, the mean pT of charged particles is smaller in γp than in pPb collisions. For both the γp and pPb samples, V1Δ is negative, V2Δ is positive, and V3Δ consistent with 0. For each multiplicity and pT range, V2Δ is larger for γp events. The γp data are consistent with model predictions that have no collective effects.
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Journal articleTumasyan A, Adam W, Andrejkovic JW, et al., 2023,
Search for medium effects using jets from bottom quarks in PbPb collisions at s<inf>NN</inf>=5.02TeV
, Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics, Vol: 844, ISSN: 0370-2693The first study of the shapes of jets arising from bottom (b) quarks in heavy ion collisions is presented. Jet shapes are studied using charged hadron constituents as a function of their radial distance from the jet axis. Lead-lead (PbPb) collision data at a nucleon-nucleon center-of-mass energy of sNN=5.02TeV were recorded by the CMS detector at the LHC, with an integrated luminosity of 1.69nb−1. Compared to proton-proton collisions, a redistribution of the energy in b jets to larger distances from the jet axis is observed in PbPb collisions. This medium-induced redistribution is found to be substantially larger for b jets than for inclusive jets.
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Journal articleTumasyan A, Adam W, Andrejkovic JW, et al., 2023,
Evidence for four-top quark production in proton-proton collisions at s=13TeV
, Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics, Vol: 844, ISSN: 0370-2693The production of four top quarks (tt¯tt¯) is studied with LHC proton-proton collision data samples collected by the CMS experiment at a center-of-mass energy of 13 TeV, and corresponding to integrated luminosities of up to 138fb−1. Events that have no leptons (all-hadronic), one lepton, or two opposite-sign leptons (where lepton refers only to prompt electrons or prompt muons) are considered. This is the first tt¯tt¯ measurement that includes the all-hadronic final state. The observed significance of the tt¯tt¯ signal in these final states of 3.9 standard deviations (1.5 expected) provides evidence for tt¯tt¯ production, with a measured cross section of 36−11+12fb. Combined with earlier CMS results in other final states, the signal significance is 4.0 standard deviations (3.2 expected). The combination returns an observed cross section of 17±4(stat)±3(syst)fb, which is consistent with the standard model prediction.
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Journal articleAaij R, Abdelmotteleb ASW, Abellan Beteta C, et al., 2023,
Measurement of the Prompt D^{0} Nuclear Modification Factor in p-Pb Collisions at sqrt[s_{NN}]=8.16 TeV.
, Phys Rev Lett, Vol: 131The production of prompt D^{0} mesons in proton-lead collisions in both the forward and backward rapidity regions at a center-of-mass energy per nucleon pair of sqrt[s_{NN}]=8.16 TeV is measured by the LHCb experiment. The nuclear modification factor of prompt D^{0} mesons is determined as a function of the transverse momentum p_{T}, and the rapidity in the nucleon-nucleon center-of-mass frame y^{*}. In the forward rapidity region, significantly suppressed production with respect to pp collisions is measured, which provides significant constraints on models of nuclear parton distributions and hadron production down to the very low Bjorken-x region of ∼10^{-5}. In the backward rapidity region, a suppression with a significance of 2.0-3.8 standard deviations compared to parton distribution functions in a nuclear environment expectations is found in the kinematic region of p_{T}>6 GeV/c and -3.25<y^{*}<-2.5, corresponding to x∼0.01.
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Journal articleTumasyan A, Adam W, Andrejkovic JW, et al., 2023,
Search for Exotic Higgs Boson Decays H→AA→4γ with Events Containing Two Merged Diphotons in Proton-Proton Collisions at sqrt[s]=13 TeV.
, Phys Rev Lett, Vol: 131We present the first direct search for exotic Higgs boson decays H→AA, A→γγ in events with two photonlike objects. The hypothetical particle A is a low-mass spin-0 particle decaying promptly to a merged diphoton reconstructed as a single photonlike object. We analyze the data collected by the CMS experiment at sqrt[s]=13 TeV corresponding to an integrated luminosity of 136 fb^{-1}. No excess above the estimated background is found. We set upper limits on the branching fraction B(H→AA→4γ) of (0.9-3.3)×10^{-3} at 95% confidence level for masses of A in the range 0.1-1.2 GeV.
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Journal articleTumasyan A, Adam W, Andrejkovic JW, et al., 2023,
Search for a charged Higgs boson decaying into a heavy neutral Higgs boson and a W boson in proton-proton collisions at $$ \sqrt{s} $$ = 13 TeV
, Journal of High Energy Physics, Vol: 2023<jats:title>A<jats:sc>bstract</jats:sc> </jats:title><jats:p>A search for a charged Higgs boson H<jats:sup><jats:italic>±</jats:italic></jats:sup> decaying into a heavy neutral Higgs boson H and a W boson is presented. The analysis targets the H decay into a pair of tau leptons with at least one of them decaying hadronically and with an additional electron or muon present in the event. The search is based on proton-proton collision data recorded by the CMS experiment during 2016–2018 at <jats:inline-formula><jats:alternatives><jats:tex-math>$$ \sqrt{s} $$</jats:tex-math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msqrt> <mml:mi>s</mml:mi> </mml:msqrt> </mml:math></jats:alternatives></jats:inline-formula> = 13 TeV, corresponding to an integrated luminosity of 138 fb<jats:sup><jats:italic>−</jats:italic>1</jats:sup>. The data are consistent with standard model background expectations. Upper limits at 95% confidence level are set on the product of the cross section and branching fraction for an H<jats:sup><jats:italic>±</jats:italic></jats:sup> in the mass range of 300–700 GeV, assuming an H with a mass of 200 GeV. The observed limits range from 0.085 pb for an H<jats:sup><jats:italic>±</jats:italic></jats:sup> mass of 300 Ge V to 0.019 pb for a mass of 700 GeV. These are the first limits on H<jats:sup><jats:italic>±</jats:italic></jats:sup> production in the H<jats:sup><jats:italic>±</jats:italic></jats:sup><jats:italic>→</jats:italic> HW<jats:sup><jats:italic>±</jats:italic></jats:sup> decay channel at the LHC.&
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Journal articleAbe K, Akhlaq N, Akutsu R, et al., 2023,
Measurements of neutrino oscillation parameters from the T2K experiment using 3.6 x 10<SUP>21</SUP> protons on target
, EUROPEAN PHYSICAL JOURNAL C, Vol: 83, ISSN: 1434-6044
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