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Journal articleSirunyan AM, Tumasyan A, Adam W, et al., 2021,
Search for new physics in top quark production with additional leptons in proton-proton collisions at root s=13 TeV using effective field theory
, The Journal of High Energy Physics, Vol: 2021, Pages: 1-54, ISSN: 1029-8479Events containing one or more top quarks produced with additional prompt leptons are used to search for new physics within the framework of an effective field theory (EFT). The data correspond to an integrated luminosity of 41.5 fb−1 of proton-proton collisions at a center-of-mass energy of 13 TeV at the LHC, collected by the CMS experiment in 2017. The selected events are required to have either two leptons with the same charge or more than two leptons; jets, including identified bottom quark jets, are also required, and the selected events are divided into categories based on the multiplicities of these objects. Sixteen dimension-six operators that can affect processes involving top quarks produced with additional charged leptons are considered in this analysis. Constructed to target EFT effects directly, the analysis applies a novel approach in which the observed yields are parameterized in terms of the Wilson coefficients (WCs) of the EFT operators. A simultaneous fit of the 16 WCs to the data is performed and two standard deviation confidence intervals for the WCs are extracted; the standard model expectations for the WC values are within these intervals for all of the WCs probed.
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Journal articleAaij R, Beteta CA, Adeva B, et al., 2021,
Observation of the Bs0 → <i>D</i><SUP>*±</SUP><i>D</i><SUP>∓</SUP> decay
, JOURNAL OF HIGH ENERGY PHYSICS, ISSN: 1029-8479- Author Web Link
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- Citations: 1
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Journal articleAaij R, Beteta CA, Adeva B, et al., 2021,
Observation of <i>CP</i> violation in two-body B<sub>(<i>s</i>)</sub><SUP>0</SUP>-meson decays to charged pions and kaons
, JOURNAL OF HIGH ENERGY PHYSICS- Cite
- Citations: 22
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Conference paperKenyon SP, Letson B, Clark M, et al., 2021,
A Charge Management System for Gravitational Reference Sensors - Design and Instrument Testing
, ISSN: 1095-323XGravitational reference sensors (GRSs) are imperative to Earth geodesy missions and gravitational wave observations in space. A typical GRS consists of a test mass (TM) surrounded by a capacitive electrode housing to perform sensitive relative position measurements and to apply small forces to the TM. This paper specifically discusses advancements in the charge management system (CMS) for the GRS being used in the LISA mission. Space radiation accumulating charge on the TM will eventually generate unwanted forces on the TM due to stray electric fields in the spacecraft. Thus, the TM charge must be kept close to a zero potential. The TM charge will be controlled in a contact-free manner by shining UV light and exploiting the photoelectric effect. A major design improvement for future missions is using UV LEDs, which can be pulsed. This facilitates more advanced charge control schemes for a continuous science measurement. The UV LEDs are housed in an aluminum block and controlled with supporting electronics via the charge management device (CMD). The CMD needs to be integrated with the spacecraft computer and needs to contain redundancy to survive the 10+ year LISA mission. The CMD is a NASA deliverable for the ESA mission and has begun the process of technology advancement and testing. The unit has custom PCBs designed to supply both continuous and pulsed current to the UV LEDs, readback telemetry data, manage CMD power needs, and synchronize with the spacecraft computer to communicate with spacecraft operators. The system achieved TRL 4 at the end of 2018 and surpassed all requirements for performance, redundancy, and lifetime. The system is capable of generating stable and robust square UV light pulses, has the capacity to drive the UV LEDs at their full dynamic range, and meets requirements on power, pulse properties, stability, and commanding speed. This technology features novel discharge methods and improvements on past missions in terms of noise level and cont
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Journal articleAaij R, Beteta CA, Ackernley T, et al., 2021,
Observation of Multiplicity Dependent Prompt <i>χ</i><sub>c1</sub> (3872) and ψ (2<i>S</i>) Production in pp Collisions
, PHYSICAL REVIEW LETTERS, Vol: 126, ISSN: 0031-9007- Cite
- Citations: 42
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Journal articleAaij R, Beteta CA, Ackernley T, et al., 2021,
Measurement of <i>CP</i> Violation in the Decay <i>B</i> plus → <i>K</i><SUP>+</SUP> π<SUP>0</SUP>
, PHYSICAL REVIEW LETTERS, Vol: 126, ISSN: 0031-9007- Cite
- Citations: 9
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Journal articleAbe K, Akhlaq N, Akutsu R, et al., 2021,
Measurements of (nu)over-bar(mu) and (nu)over-bar(mu) + nu(mu) charged-current cross-sections without detected pions or protons on water and hydrocarbon at a mean anti-neutrino energy of 0.86 GeV
, Progress of Theoretical and Experimental Physics, Vol: 2021, ISSN: 0033-068XWe report measurements of the flux-integrated ν̅μ and ν̅μ + νμ charged-current cross-sections on water and hydrocarbon targets using the T2K anti-neutrino beam with a mean beam energy of 0.86 GeV. The signal is defined as the (anti-)neutrino charged-current interaction with one induced μ± and no detected charged pion or proton. These measurements are performed using a new WAGASCI module recently added to the T2K setup in combination with the INGRID Proton Module. The phase space of muons is restricted to the high-detection efficiency region, pμ>400 MeV/c and θμ<30∘, in the laboratory frame. An absence of pions and protons in the detectable phase spaces of pπ>200 MeV/c, θπ<70∘ and pp>600 MeV/c, θp<70∘ is required. In this paper, both the ν¯¯¯μ cross-sections and ν¯¯¯μ+νμ cross-sections on water and hydrocarbon targets and their ratios are provided by using the D’Agostini unfolding method. The results of the integrated ν¯¯¯μ cross-section measurements over this phase space are σH2O=(1.082±0.068(stat.)+0.145−0.128(syst.))×10−39cm2/nucleon, σCH=(1.096±0.054(stat.)+0.132−0.117(syst.))×10−39cm2/nucleon, and σH2O/σCH=0.987±0.078(stat.)+0.093−0.090(syst.). The ν¯¯¯μ+νμ cross-section is σH2O=(1.155±0.064(stat.)+0.148−0.129(syst.))×10−39cm2/nucleon, σCH=(1.159±0.049(stat.)+0.129−0.115(syst.))×10−39cm2/nucleon, and σH2O/σCH=0.996±0.069(stat.)+0.083−0.078(syst.).
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Journal articleKhorramian A, Leader E, Stamenov DB, et al., 2021,
Sensitivity of strange quark polarization to flavor <i>SU</i>(3) symmetry breaking
, PHYSICAL REVIEW D, Vol: 103, ISSN: 2470-0010- Cite
- Citations: 6
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Journal articleSirunyan AM, Tumasyan A, Adam W, et al., 2021,
Search for dark photons in Higgs boson production via vector boson fusion in proton-proton collisions at root s=13 TeV
, The Journal of High Energy Physics, Vol: 2021, Pages: 1-43, ISSN: 1029-8479A search is presented for a Higgs boson that is produced via vector boson fusion and that decays to an undetected particle and an isolated photon. The search is performed by the CMS collaboration at the LHC, using a data set corresponding to an integrated luminosity of 130 fb−1, recorded at a center-of-mass energy of 13 TeV in 2016–2018. No significant excess of events above the expectation from the standard model background is found. The results are interpreted in the context of a theoretical model in which the undetected particle is a massless dark photon. An upper limit is set on the product of the cross section for production via vector boson fusion and the branching fraction for such a Higgs boson decay, as a function of the Higgs boson mass. For a Higgs boson mass of 125 GeV, assuming the standard model production rates, the observed (expected) 95% confidence level upper limit on the branching fraction is 3.5 (2.8)%. This is the first search for such decays in the vector boson fusion channel. Combination with a previous search for Higgs bosons produced in association with a Z boson results in an observed (expected) upper limit on the branching fraction of 2.9 (2.1)% at 95% confidence level.
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Journal articleAaij R, Abellán Beteta C, Ackernley T, et al., 2021,
Measurement of the CKM angle γ and Bs0‐B¯s0 mixing frequency with Bs0→Ds∓h±π±π∓ decays
, Journal of High Energy Physics, Vol: 2021The CKM angle γ is measured for the first time from mixing-induced CP violation between Bs0→Ds∓K±π±π∓ and B¯s0→Ds±K∓π∓π± decays reconstructed in proton-proton collision data corresponding to an integrated luminosity of 9 fb<sup>−1</sup> recorded with the LHCb detector. A time-dependent amplitude analysis is performed to extract the CP-violating weak phase γ − 2β<inf>s</inf> and, subsequently, γ by taking the Bs0‐B¯s0 mixing phase β<inf>s</inf> as an external input. The measurement yields γ = (44 ± 12)° modulo 180°, where statistical and systematic uncertainties are combined. An alternative model-independent measurement, integrating over the five-dimensional phase space of the decay, yields γ=(44−13+20)° modulo 180°. Moreover, the Bs0‐B¯s0 oscillation frequency is measured from the flavour-specific control channel Bs0→Ds−π+π+π− to be ∆m<inf>s</inf> = (17.757 ± 0.007(stat) ± 0.008(syst)) ps<sup>−1</sup>, consistent with and more precise than the current world-average value. [Figure not available: see fulltext.]
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Journal articleLong KR, Lucchesi D, Palmer MA, et al., 2021,
Muon colliders to expand frontiers of particle physics
, Nature Physics, Vol: 17, Pages: 289-292, ISSN: 1745-2473Muon colliders offer enormous potential for the exploration of the particle physics frontier but are challenging to realize. A new international collaboration is forming to make such a muon collider a reality.
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Journal articleSirunyan AM, Tumasyan A, Adam W, et al., 2021,
Measurement of the inclusive and differential Higgs boson production cross sections in the leptonic WW decay mode at p root s=13 TeV
, The Journal of High Energy Physics, Vol: 2021, Pages: 1-48, ISSN: 1029-8479Measurements of the fiducial inclusive and differential production cross sections of the Higgs boson in proton-proton collisions at s√ = 13 TeV are performed using events where the Higgs boson decays into a pair of W bosons that subsequently decay into a final state with an electron, a muon, and a pair of neutrinos. The analysis is based on data collected with the CMS detector at the LHC during 2016–2018, corresponding to an integrated luminosity of 137 fb−1. Production cross sections are measured as a function of the transverse momentum of the Higgs boson and the associated jet multiplicity. The Higgs boson signal is extracted and simultaneously unfolded to correct for selection efficiency and resolution effects using maximum-likelihood fits to the observed distributions in data. The integrated fiducial cross section is measured to be 86.5 ± 9.5 fb, consistent with the Standard Model expectation of 82.5 ± 4.2 fb. No significant deviation from the Standard Model expectations is observed in the differential measurements.
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Journal articleSirunyan AM, Tumasyan A, Adam W, et al., 2021,
Measurements of pp -> ZZ production cross sections and constraints on anomalous triple gauge couplings at root s=13 TeV
, European Physical Journal C: Particles and Fields, Vol: 81, Pages: 1-30, ISSN: 1124-1861The production of Z boson pairs in proton–proton (pp) collisions, pp→(Z/γ∗)(Z/γ∗)→2ℓ2ℓ′, where ℓ,ℓ′=e or μ, is studied at a center-of-mass energy of 13TeV with the CMS detector at the CERN LHC. The data sample corresponds to an integrated luminosity of 137fb−1, collected during 2016–2018. The ZZ production cross section, σtot(pp→ZZ)=17.4±0.3(stat)±0.5(syst)±0.4(theo)±0.3(lumi) pb, measured for events with two pairs of opposite-sign, same-flavor leptons produced in the mass region 60<mℓ+ℓ−<120GeV is consistent with standard model predictions. Differential cross sections are also measured and agree with theoretical predictions. The invariant mass distribution of the four-lepton system is used to set limits on anomalous ZZZ and ZZγ couplings.
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Journal articleAmhis Y, Banerjee S, Ben-Haim E, et al., 2021,
Averages of <i>b</i>-hadron, <i>c</i>-hadron, and τ-lepton properties as of 2018 Heavy Flavor Averaging Group (HFLAV)
, EUROPEAN PHYSICAL JOURNAL C, Vol: 81, ISSN: 1434-6044- Cite
- Citations: 169
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Journal articleAaij R, Beteta CA, Adeva B, et al., 2021,
Search for heavy neutral leptons in W plus . μ plus μ± jet decays
, EUROPEAN PHYSICAL JOURNAL C, Vol: 81, ISSN: 1434-6044- Cite
- Citations: 30
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Journal articleAaij R, Abellán Beteta C, Ackernley T, et al., 2021,
First Observation of the Decay B_{s}^{0}→K^{-}μ^{+}ν_{μ} and a Measurement of |V_{ub}|/|V_{cb}|.
, Phys Rev Lett, Vol: 126The first observation of the suppressed semileptonic B_{s}^{0}→K^{-}μ^{+}ν_{μ} decay is reported. Using a data sample recorded in pp collisions in 2012 with the LHCb detector, corresponding to an integrated luminosity of 2 fb^{-1}, the branching fraction B(B_{s}^{0}→K^{-}μ^{+}ν_{μ}) is measured to be [1.06±0.05(stat)±0.08(syst)]×10^{-4}, where the first uncertainty is statistical and the second one represents the combined systematic uncertainties. The decay B_{s}^{0}→D_{s}^{-}μ^{+}ν_{μ}, where D_{s}^{-} is reconstructed in the final state K^{+}K^{-}π^{-}, is used as a normalization channel to minimize the experimental systematic uncertainty. Theoretical calculations on the form factors of the B_{s}^{0}→K^{-} and B_{s}^{0}→D_{s}^{-} transitions are employed to determine the ratio of the Cabibbo-Kobayashi-Maskawa matrix elements |V_{ub}|/|V_{cb}| at low and high B_{s}^{0}→K^{-} momentum transfer.
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Journal articleAaij R, Beteta CA, Ackernley T, et al., 2021,
First Observation of the Decay <i>B<sub>s</sub></i><SUP>0</SUP> → <i>K</i><SUP>-</SUP>μ<SUP>+</SUP>ν<sub>μ</sub> and a Measurement of |<i>V<sub>ub</sub></i>|/|<i>V<sub>cb</sub></i>|
, PHYSICAL REVIEW LETTERS, Vol: 126, ISSN: 0031-9007- Author Web Link
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- Citations: 18
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Journal articleGorham PW, Ludwig A, Deaconu C, et al., 2021,
Unusual Near-Horizon Cosmic-Ray-like Events Observed by ANITA-IV
, PHYSICAL REVIEW LETTERS, Vol: 126, ISSN: 0031-9007- Cite
- Citations: 18
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Journal articleAaij R, Beteta CA, Adeva B, et al., 2021,
Measurement of the CKM angle γ in <i>B</i><SUP>±</SUP> → <i>DK</i><SUP>±</SUP> and <i>B</i><SUP>±</SUP> → <i>Dπ</i><SUP>±</SUP> decays with <i>D</i> → <i>K</i><sub>S</sub><SUP>0</SUP><i>h</i><SUP>+</SUP><i>h<SUP>-</SUP></i>
, JOURNAL OF HIGH ENERGY PHYSICS, ISSN: 1029-8479- Cite
- Citations: 21
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Journal articleSirunyan AM, Tumasyan A, Adam W, et al., 2021,
Studies of charm and beauty hadron long-range correlations in pp and pPb collisions at LHC energies
, Physics Letters B: Nuclear Physics and Particle Physics, Vol: 813, Pages: 1-25, ISSN: 0370-2693Measurements of the second Fourier harmonic coefficient (v2) of the azimuthal distributions of promptand nonprompt D0 mesons produced in pp and pPb collisions are presented. Nonprompt D0 mesons comefrom beauty hadron decays. The data samples are collected by the CMS experiment at nucleon-nucleoncenter-of-mass energies of 13 and 8.16 TeV, respectively. In high multiplicity pp collisions, v2 signalsfor prompt charm hadrons are reported for the first time, and are found to be comparable to those forlight-flavor hadron species over a transverse momentum (pT) range of 2–6 GeV. Compared at similarevent multiplicities, the prompt D0 meson v2 values in pp and pPb collisions are similar in magnitude.The v2 values for open beauty hadrons are extracted for the first time via nonprompt D0 mesons inpPb collisions. For pT in the range of 2–5 GeV, the results suggest that v2 for nonprompt D0 mesons issmaller than that for prompt D0 mesons. These new measurements indicate a positive charm hadron v2in pp collisions and suggest a mass dependence in v2 between charm and beauty hadrons in the pPbsystem. These results provide insights into the origin of heavy-flavor quark collectivity in small systems
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Journal articleAaij R, Beteta CA, Ackernley T, et al., 2021,
Measurement of differential <i>b</i>(<i>b</i>)over-barand <i>c</i>(<i>c</i>)over-bar-dijet cross-sections in the forward region of <i>pp</i> collisions at √<i>s</i>=13 TeV
, JOURNAL OF HIGH ENERGY PHYSICS, ISSN: 1029-8479- Cite
- Citations: 14
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Journal articleAaij R, Beteta CA, Ackernley T, et al., 2021,
Study of B<sub>s</sub><SUP>0</SUP> → J/ψπ<SUP>+</SUP>π<SUP>-</SUP>K<SUP>+</SUP>K<SUP>-</SUP> decays
, JOURNAL OF HIGH ENERGY PHYSICS, ISSN: 1029-8479- Cite
- Citations: 9
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Journal articleAbratenko P, Alrashed M, An R, et al., 2021,
The continuous readout stream of the MicroBooNE liquid argon time projection chamber for detection of supernova burst neutrinos
, Journal of Instrumentation, Vol: 16The MicroBooNE continuous readout stream is a parallel readout of the MicroBooNE liquid argon time projection chamber (LArTPC) which enables detection of non-beam events such as those from a supernova neutrino burst. The low energies of the supernova neutrinos and the intense cosmic-ray background flux due to the near-surface detector location makes triggering on these events very challenging. Instead, MicroBooNE relies on a delayed trigger generated by SNEWS (the Supernova Early Warning System) for detecting supernova neutrinos. The continuous readout of the LArTPC generates large data volumes, and requires the use of real-time compression algorithms (zero suppression and Huffman compression) implemented in an FPGA (field-programmable gate array) in the readout electronics. We present the results of the optimization of the data reduction algorithms, and their operational performance. To demonstrate the capability of the continuous stream to detect low-energy electrons, a sample of Michel electrons from stopping cosmic-ray muons is reconstructed and compared to a similar sample from the lossless triggered readout stream.
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Journal articleAbratenko P, Alrashed M, An R, et al., 2021,
Vertex-finding and reconstruction of contained two-track neutrino events in the MicroBooNE detector
, Journal of Instrumentation, Vol: 16We describe algorithms developed to isolate and accurately reconstruct two-track events that are contained within the MicroBooNE detector. This method is optimized to reconstruct two tracks of lengths longer than 5cm. This code has applications to searches for neutrino oscillations and measurements of cross sections using quasi-elastic-like charged current events. The algorithms we discuss will be applicable to all detectors running in Fermilab's Short Baseline Neutrino program (SBN), and to any future liquid argon time projection chamber (LArTPC) experiment with beam energies ∼ 1 GeV. The algorithms are publicly available on a GITHUB repository [1]. This reconstruction offers a complementary and independent alternative to the Pandora reconstruction package currently in use in LArTPC experiments, and provides similar reconstruction performance for two-track events.
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Journal articleKhachatryan V, Sirunyan AM, Tumasyan A, et al., 2021,
The very forward CASTOR calorimeter of the CMS experiment
, Journal of Instrumentation, Vol: 16, Pages: 1-65, ISSN: 1748-0221The physics motivation, detector design, triggers, calibration, alignment, simulation, and overall performance of the very forward CASTOR calorimeter of the CMS experiment are reviewed. The CASTOR Cherenkov sampling calorimeter is located very close to the LHC beam line, at a radial distance of about 1cm from the beam pipe, and at 14.4m from the CMS interaction point, covering the pseudorapidity range of −6.6 < η < −5.2. It was designed to withstand high ambient radiation and strong magnetic fields. The performance of the detector in measurements of forward energy density, jets, and processes characterized by rapidity gaps, is reviewed using data collected in proton and nuclear collisions at the LHC.
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Journal articleAdam W, Bergauer T, Bloch D, et al., 2021,
The CMS Phase-1 pixel detector upgrade
, JOURNAL OF INSTRUMENTATION, Vol: 16, ISSN: 1748-0221- Cite
- Citations: 6
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Journal articleShimano S, Ohkawa R, Nambu M, et al., 2021,
Marked Changes in Serum Amyloid A Distribution and High-Density Lipoprotein Structure during Acute Inflammation
, BIOMED RESEARCH INTERNATIONAL, Vol: 2021, ISSN: 2314-6133 -
Journal articleSirunyan AM, Tumasyan A, Adam W, et al., 2021,
Search for the lepton flavor violating decay tau -> 3 mu in proton-proton collisions at root s=13 TeV
, The Journal of High Energy Physics, Vol: 2021, Pages: 1-37, ISSN: 1029-8479Results are reported from a search for the lepton flavor violating decay τ → 3μ in proton-proton collisions at s√ = 13 TeV. The data sample corresponds to an integrated luminosity of 33.2 fb−1 recorded by the CMS experiment at the LHC in 2016. The search exploits τ leptons produced in both W boson and heavy-flavor hadron decays. No significant excess above the expected background is observed. An upper limit on the branching fraction ℬ(τ → 3μ) of 8.0 × 10−8 at 90% confidence level is obtained, with an expected upper limit of 6.9 × 10−8.
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Journal articleAbe K, Akhlaq N, Akutsu R, et al., 2021,
T2K measurements of muon neutrino and antineutrino disappearance using 3.13 x 10(21) protons on target
, Physical Review D: Particles, Fields, Gravitation and Cosmology, Vol: 103, Pages: 1-9, ISSN: 1550-2368We report measurements by the T2K experiment of the parameters θ23 and Δm232, which govern the disappearance of muon neutrinos and antineutrinos in the three-flavor PMNS neutrino oscillation model at T2K’s neutrino energy and propagation distance. Utilizing the ability of the experiment to run with either a mainly neutrino or a mainly antineutrino beam, muon-like events from each beam mode are used to measure these parameters separately for neutrino and antineutrino oscillations. Data taken from 1.49×1021 protons on target (POT) in neutrino mode and 1.64×1021 POT in antineutrino mode are used. The best-fit values obtained by T2K were sin2(θ23)=0.51+0.06−0.07(0.43+0.21−0.05) and Δm232=2.47+0.08−0.09(2.50+0.18−0.13)×10−3 eV2/c4 for neutrinos (antineutrinos). No significant differences between the values of the parameters describing the disappearance of muon neutrinos and antineutrinos were observed. An analysis using an effective two-flavor neutrino oscillation model where the sine of the mixing angle is allowed to take nonphysical values larger than 1 is also performed to check the consistency of our data with the three-flavor model. Our data were found to be consistent with a physical value for the mixing angle.
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Journal articleSirunyan AM, Tumasyan A, Adam W, et al., 2021,
Evidence for Higgs boson decay to a pair of muons
, The Journal of High Energy Physics, Vol: 2021, ISSN: 1029-8479Evidence for Higgs boson decay to a pair of muons is presented. This result combines searches in four exclusive categories targeting the production of the Higgs boson via gluon fusion, via vector boson fusion, in association with a vector boson, and in association with a top quark-antiquark pair. The analysis is performed using proton-proton collision data at s√ = 13 TeV, corresponding to an integrated luminosity of 137 fb−1, recorded by the CMS experiment at the CERN LHC. An excess of events over the back- ground expectation is observed in data with a significance of 3.0 standard deviations, where the expectation for the standard model (SM) Higgs boson with mass of 125.38 GeV is 2.5. The combination of this result with that from data recorded at s√ = 7 and 8 TeV, corresponding to integrated luminosities of 5.1 and 19.7 fb−1, respectively, increases both the expected and observed significances by 1%. The measured signal strength, relative to the SM prediction, is 1.19+0.40−0.39(stat)+0.15−0.14(syst). This result constitutes the first evidence for the decay of the Higgs boson to second generation fermions and is the most precise measurement of the Higgs boson coupling to muons reported to date.
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