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Search for the lepton flavour violating decay B+→K+μ−τ+ using B∗0s2 decays
Journal of High Energy Physics. 2020. Vol. 06. No. 129. P. 1-18.
Aaij R., Beteta C. A., K. Arzymatov, V. Belavin, A. Boldyrev, M. Borisyak, D. Derkach, Hushchyn M., N. Kazeev, A. Maevskiy, F. Ratnikov, A. Ryzhikov, A. Ustyuzhanin
A search is presented for the lepton flavour violating decay B+→K+μ−τ+using a sample of proton--proton collisions at centre-of-mass energies of 7, 8, and 13 TeV, collected with the LHCb detector and corresponding to a total integrated luminosity of 9 fb−1. The τ leptons are selected inclusively, primarily via decays with a single charged particle. The four-momentum of the τ lepton is determined by using B+ mesons from B∗0s2→B+K− decays. No significant excess is observed, and an upper limit is set on the branching fraction B(B+→K+μ−τ+)<3.9×10−5 at 90 confidence level. The obtained limit is comparable to the world-best limit.
Aaboud M., Glazov A., et a. et al., The European Physical Journal C - Particles and Fields 2016 Vol. 76 No. 12 P. 1-42
he algorithms used by the ATLAS Collaboration to reconstruct and identify prompt photons are described. Measurements of the photon identification efficiencies are reported, using 4.9 fb−1 of pp collision data collected at the LHC at s√=7 TeV and 20.3 fb−1 at s√=8 TeV . The efficiencies are measured separately for converted and unconverted photons, in ...
Added: August 7, 2018
Aaij R., Beteta C. A., K. Arzymatov et al., Physical Review Letters 2020 Vol. 124 No. 8 P. 1-12
We report four narrow peaks in the Ξb0K- mass spectrum obtained using pp collisions at center-of-mass energies of 7, 8, and 13 TeV, corresponding to a total integrated luminosity of 9 fb-1 recorded by the LHCb experiment. Referring to these states by their mass, the mass values are m[Ωb(6316)-]=6315.64±0.31±0.07±0.50 MeV, m[Ωb(6330)-]=6330.30±0.28±0.07±0.50 MeV, m[Ωb(6340)-]=6339.71±0.26±0.05±0.50 MeV, m[Ωb(6350)-]=6349.88±0.35±0.05±0.50 MeV, where the uncertainties are statistical, ...
Added: September 16, 2020
Сапронов А. А., Aad G., Glazov A., Physical Review D - Particles, Fields, Gravitation and Cosmology 2017 Vol. 96 No. 7 P. 072002-1-072002-36
Jet energy scale measurements and their systematic uncertainties are reported for jets measured with the ATLAS detector using proton-proton collision data with a center-of-mass energy of s=13 TeV, corresponding to an integrated luminosity of 3.2 fb-1 collected during 2015 at the LHC. Jets are reconstructed from energy deposits forming topological clusters of calorimeter cells, using the anti-kt ...
Added: August 7, 2018
Aaij R., Arzymatov K., Belavin V. et al., Physical Review Letters 2020 Vol. 125 No. 24 Article 242001
The only anticipated resonant contributions to B+→D+D−K+ decays are charmonium states in the D+D− channel. A model-independent analysis, using LHCb proton-proton collision data taken at center-of-mass energies of √s=7, 8, and 13 TeV, corresponding to a total integrated luminosity of 9 fb−1, is carried out to test this hypothesis. The description of the data assuming that resonances only manifest in decays to the D+D− pair ...
Added: September 1, 2021
Aaij R., Boldyrev A., Beteta C. A. et al., Physical Review Letters 2020 Vol. 124 No. 3 P. 031801
Observations are reported of different sources of CP violation from an amplitude analysis of B+→π+π+π− decays, based on a data sample corresponding to an integrated luminosity of 3 fb−1 of pp collisions recorded with the LHCb detector. A large CP asymmetry is observed in the decay amplitude involving the tensor f2(1270) resonance, and in addition significant CP violation is found in the π+π−S wave at low invariant mass. The presence of CP violation related ...
Added: December 7, 2020
Borisyak M., Belous M., Derkach D. et al., Journal of Instrumentation 2017
High-energy physics experiments rely on reconstruction of the trajectories of particles produced at the interaction point. This is a challenging task, especially in the high track multiplicity environment generated by p-p collisions at the LHC energies. A typical event includes hundreds of signal examples (interesting decays) and a significant amount of noise (uninteresting examples). This ...
Added: October 18, 2017
Aaij R., Beteta C. A., Borisyak M. et al., Physical Review Letters 2020 Vol. 124 No. 4 P. 1-12
Searches are performed for both prompt-like and long-lived dark photons, A′, produced in proton-proton collisions at a center-of-mass energy of 13 TeV. These searches look for A′→μ+μ− decays using a data sample corresponding to an integrated luminosity of 5.5/fb collected with the LHCb detector. Neither search finds evidence for a signal, and 90 confidence-level exclusion ...
Added: September 16, 2020
Mizuk R., Aushev T., Pakhlov P. et al., Journal of High Energy Physics 2019 P. 1-30
We report a new measurement of the e+e−→Υ(nS)π+π− (n=1,2,3) cross sections at energies from 10.52 to 11.02 GeV using data collected with the Belle detector at the KEKB asymmetric-energy e+e− collider. We observe a new structure in the energy dependence of the cross sections; if described by a Breit-Wigner function its mass and width are ...
Added: June 5, 2020
Aaij R., Beteta C. A., Borisyak M. et al., Physical Review D - Particles, Fields, Gravitation and Cosmology 2020 Vol. 102 No. 9 Article 092005
A study of the lineshape of theχc1ð3872Þstate is made using a data sample corresponding to anintegrated luminosity of3fb−1collected inppcollisions at center-of-mass energies of 7 and 8 TeV withthe LHCb detector. Candidateχc1ð3872Þandψð2SÞmesons fromb-hadron decays are selected in theJ=ψπþπ−decay mode. Describing the lineshape with a Breit-Wigner function, the mass splitting betweentheχc1ð3872Þandψð2SÞstates,Δm, and the width of theχc1ð3872Þstate,ΓBW, are ...
Added: December 6, 2020
Ustyuzhanin A., Likhomanenko T., Derkach D. et al., Journal of High Energy Physics 2016
The decays Λb0 → ψ(2S)pK− and Λb0 → J/ψπ+π−pK− are observed in a data sample corresponding to an integrated luminosity of 3 fb−1, collected in proton-proton collisions at 7 and 8 TeV centre-of-mass energies by the LHCb detector. The ψ(2S) mesons are reconstructed through the decay modes ψ(2S) → μ+μ− and ψ(2S) → J/ψπ+π−.
The branching fractions relative to that of Λb0 → J/ψpK− are measured to be
M(Λ0b)=5619.65±0.17±0.17 MeV/c2,M(Λb0)=5619.65±0.17±0.17 MeV/c2, ...
Added: October 23, 2016
Derkach D., Hushchyn M., Kazeev N. et al., Physics Letters B 2019 Vol. 797 P. 134789
Decays of B 0 s and B 0 s mesons into J /ψ π + π − final states are studied in a data sample corresponding to 1.9 fb − 1 of integrated luminosity collected with the LHCb detector in 13 TeV pp collisions. A time-dependent amplitude analysis is used to determine the final-state resonance ...
Added: March 11, 2020
Borisyak M., Ratnikov F., Ustyuzhanin A., Physical Review Letters 2017 Vol. 118 No. 25 P. 251802-251812
A search for the rare decays Bs0→τ+τ- and B0→τ+τ- is performed using proton–proton collision data collected with the LHCb detector. The data sample corresponds to an integrated luminosity of 3 fb-1 collected in 2011 and 2012. The τ leptons are reconstructed through the decay τ-→π-π+π-ντ. Assuming no contribution from B0→τ+τ- decays, an upper limit is set ...
Added: October 22, 2017
Aushev T., Mizuk R., Pakhlov P. et al., Physical Review D - Particles, Fields, Gravitation and Cosmology 2019 Vol. 99 No. 11 P. 1-8
We report a search for X(3872) and X(3915) in B+→χc1π0K+ decays. We set an upper limit of B(B+→X(3872)K+)×B(X(3872)→χc1π0) <8.1×10−6 and B(B+→X(3915)K+)×B(X(3915)→χc1π0) <3.8×10−5 at 90\% confidence level. We also measure B(X(3872)→χc1π0)/B(X(3872)→J/ψπ+π−)<0.97 at 90\% confidence level. The results reported here are obtained from 772×106 BB¯¯¯¯ events collected at the Υ(4S) resonance with the Belle detector at the ...
Added: June 5, 2020
Kazeev N., Derkach D., Hushchyn M. et al., Physical Review D - Particles, Fields, Gravitation and Cosmology 2018 Vol. 97 P. 091101-1-091101-10
A search for the flavor-changing neutral-current decay Λ c+→ p μ+ μ− is reported using a
data set corresponding to an integrated luminosity of 3.0 fb− 1 collected by the LHCb
Collaboration. No significant signal is observed outside of the dimuon mass regions around
the ϕ and ω resonances, and an upper limit is placed on the branching ...
Added: October 9, 2018
Aaij R., K. Arzymatov, V. Belavin et al., Physical Review D - Particles, Fields, Gravitation and Cosmology 2020 Vol. 101 No. 7 Article 072004
The element |Vcb| of the Cabibbo-Kobayashi-Maskawa matrix is measured using semileptonic B0s decays produced in proton-proton collision data collected with the LHCb detector at center-of-mass energies of 7 and 8 TeV, corresponding to an integrated luminosity of 3 fb−1. Rates of B0s→D−sμ+νμ and B0s→D∗−sμ+νμ decays are analyzed using hadronic form-factor parametrizations derived either by Caprini, ...
Added: September 16, 2020
M. Borisyak, Derkach D., Ratnikov F. et al., The European Physical Journal C - Particles and Fields 2017 Vol. 10 No. C77 P. 678-690
A search for the decay K0S→μ+μ− is performed, based on a data sample of proton-proton collisions corresponding to an integrated luminosity of 3 fb−1, collected by the LHCb experiment at centre-of-mass energies of 7 and 8 TeV. The observed yield is consistent with the background-only hypothesis, yielding a limit on the branching fraction of B(K0S→μ+μ−)<0.8 (1.0)×10−9 ...
Added: October 23, 2017
Aaij R., Beteta C. A., Boldyrev A. et al., Physical Review Letters 2021 Vol. 126 No. 12 P. 1-11
Using pppp collision data corresponding to an integrated luminosity of 5.4fb−15.4fb−1 collected with the LHCb detector at a center-of-mass energy of 13TeV13TeV, the B0→D−D+K+π−B0→D−D+K+π− decay is studied. A new excited D+sDs+ meson is observed decaying into the D+K+π−D+K+π− final state with large statistical significance. The pole mass and width, and the spin-parity of the new state are measured with an amplitude analysis to be mR=2591±6±7MeVmR=2591±6±7MeV, ΓR=89±16±12MeVΓR=89±16±12MeV and JP=0−JP=0−, where the ...
Added: August 31, 2021
Maevskiy, A., Boldyrev, A, Derkach, D. et al., Journal of High Energy Physics 2019 No. 09(2019)28 P. 1-19
Using proton-proton collision data, collected with the LHCb detector and corresponding to 1.0, 2.0 and 1.9 fb−1 of integrated luminosity at the centre-of-mass energies of 7, 8, and 13 TeV, respectively, the decay Λ0b→χc1Λb0→χc1(3872)pK− with χc1(3872) → J/ψ π+π− is observed for the first time. The significance of the observed signal is in excess of seven standard deviations. It ...
Added: October 22, 2019
Derkach D., Ustyuzhanin A., Rogozhnikov A. et al., Physical Review Letters 2016 Vol. 116 No. 24 P. 241601
Violations of $\CPT$ symmetry and Lorentz invariance are searched for by
studying interference effects in $\Bd$ mixing and in $\Bs$ mixing. Samples of
$\Bd\to\jpsi\KS$ and $\Bs\to\jpsi\Kp\Km$ decays are recorded by the LHCb
detector in proton--proton collisions at centre-of-mass energies of 7 and 8\tev,
corresponding to an integrated luminosity of 3\invfb. No periodic variations of
the particle-antiparticle mass differences are found, ...
Added: October 21, 2016
Derkach D., Borisyak M., Ustyuzhanin A. et al., Physics Letters B 2016 No. 762 P. 253-262
A time-dependent angular analysis of Bs0→ψ(2S)ϕ decays is performed using data recorded by the LHCb experiment. The data set corresponds to an integrated luminosity of 3.0fb−1 collected during Run 1 of the LHC. The CP -violating phase and decay-width difference of the Bs0 system are measured to be ϕs=0.23−0.28+0.29±0.02rad and ΔΓs=0.066−0.044+0.041±0.007ps−1 , respectively, where the ...
Added: October 21, 2016
The LHCb C., K. Arzymatov, V. Belavin et al., Journal of High Energy Physics 2020 Vol. 05 Article 140
The ratio of branching fractions of the decays Λb0 {\Lambda}_b^0 Λb0 → pK−^{−}−e+^{+}+e−^{−}− and Λb0 {\Lambda}_b^0 Λb0 → pK−^{−}−μ+^{+}+μ−^{−}−,RpK−1 {R}_{pK}^{-1} RpK−1, is measured for the first time using proton-proton collision data corresponding to an integrated luminosity of 4.7 fb−1^{−1}−1 recorded with the LHCb experiment at center-of-mass energies of 7, 8 and 13 TeV. In the ...
Added: September 17, 2020
Ustyuzhanin A., Derkach D., Rogozhnikov A. et al., Physical Review Letters 2016 Vol. 117 No. 8
A full amplitude analysis of Λ 0 b → J/ψ pπ− decays is performed with a data sample acquired with the LHCb detector from 7 and 8 TeV pp collisions, corresponding to an integrated luminosity of 3 fb−1 . A significantly better description of the data is achieved when, in addition to the previously observed ...
Added: October 23, 2016
Derkach D., Ratnikov F., Ustyuzhanin A., World Scientific Publishing Co., 2022
The Higgs boson discovery at the Large Hadron Collider in 2012 relied on boosted decision trees. Since then, high energy physics (HEP) has applied modern machine learning (ML) techniques to all stages of the data analysis pipeline, from raw data processing to statistical analysis. The unique requirements of HEP data analysis, the availability of high-quality ...
Added: September 21, 2022
Сапронов А. А., Aad G., Glazov A., Journal of High Energy Physics 2017 Vol. 1710 No. 182 P. 1-60
A search is conducted for new resonant and non-resonant high-mass phenomena in dielectron and dimuon final states. The search uses 36.1 fb−1 of proton-proton collision data, collected at s√=13 TeV by the ATLAS experiment at the LHC in 2015 and 2016. No significant deviation from the Standard Model prediction is observed. Upper limits at 95% ...
Added: August 7, 2018