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Precision measurement of the 𝛯++𝑐𝑐 mass
Journal of High Energy Physics. 2020. Vol. 02. No. 049. P. 1-17.
Aaij R., Beteta C. A., A. Boldyrev, D. Derkach, M. Hushchyn, N. Kazeev, A. Maevskiy, F. Ratnikov, A. Ustyuzhanin, K. Arzymatov, V. Belavin, M. Borisyak
A measurement of the Ξ++cc mass is performed using data collected by the LHCb experiment between 2016 and 2018 in pppp collisions at a centre-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 5.6 fb−1fb−1. The Ξ++cc candidates are reconstructed via the decay modes Ξ++cc→Λ+cK−π+π+ and Ξ++cc→Ξ+cπ+. The result, 3621.55±0.23(stat)±0.30(syst)MeV/c2, is the most precise measurement of the Ξ++cc mass to date.
The LHCb C., A. Boldyrev, D. Derkach et al., Journal of High Energy Physics 2020 Vol. 03 Article 146
The Cabibbo-suppressed semileptonic decay B+→pp⎯⎯⎯μ+νμ is observed for the first time using a sample of pp collisions corresponding to an integrated luminosity of 1.0, 2.0 and 1.7fb−1 at centre-of-mass energies of 7, 8 and 13TeV, respectively. The differential branching fraction is measured as a function of the pp⎯⎯⎯ invariant mass using the decay mode B+→J/ψK+ for normalisation. The total branching fraction is measured to ...
Added: September 16, 2020
A. Boldyrev, D. Derkach, M. Hushchyn et al., Physical Review Letters 2019 Vol. 123 No. 24 P. 1-11
A search for the lepton-flavor violating decays B+→K+μ±e∓ is performed using a sample of proton-proton collision data, collected with the LHCb experiment at center-of-mass energies of 7 and 8 TeV and corresponding to an integrated luminosity of 3 fb−1. No significant signal is observed, and upper limits on the branching fractions are set as B(B+→K+μ−e+)<7.0(9.5)×10−9 and B(B+→K+μ+e−)<6.4(8.8)×10−9 at 90% (95)% confidence level. The results ...
Added: February 20, 2020
A. Boldyrev, D. Derkach, M. Hushchyn et al., Physical Review Letters 2019 Vol. 123 No. 15 P. 1-11
We report the observation of a new structure in the Λ0bπ+π− spectrum using the full LHCb data set of pp collisions, corresponding to an integrated luminosity of 9 fb−1, collected at √s=7, 8, and 13 TeV. A study of the structure suggests its interpretation as a superposition of two almost degenerate narrow states. The masses and widths of these states are measured to ...
Added: February 18, 2020
The LHCb c., A. Boldyrev, D. Derkach et al., Journal of High Energy Physics 2020 Vol. 03 Article 147
The decay-time-dependent CP asymmetry in B0→D∗±D∓ decays is measured using a data set corresponding to an integrated luminosity of 9fb−1 recorded by the LHCb detector in proton-proton collisions at centre-of-mass energies of 7, 8 and 13 TeV. The CP parameters are measured as
SD∗D=−0.861±0.077(stat)±0.019(syst),
ΔSD∗D=0.019±0.075(stat)±0.012(syst),
CD∗D=−0.059±0.092(stat)±0.020(syst),
ΔCD∗D=−0.031±0.092(stat)±0.016(syst),
D∗D=0.008±0.014(stat)±0.006(syst).
The analysis provides the most precise single measurement of CP violation in this decay channel to date. All parameters are consistent with their ...
Added: September 16, 2020
A. Boldyrev, D. Derkach, M. Hushchyn et al., Journal of High Energy Physics 2019 No. 12 P. 155
A measurement of the time-dependent CP-violating asymmetry in B0 s → φφ decays is presented. Using a sample of proton-proton collision data corresponding to an integrated luminosity of 5.0 fb−1 collected by the LHCb experiment at centre-of-mass energies √ s = 7 TeV in 2011, 8 TeV in 2012 and 13 TeV in 2015 and ...
Added: February 20, 2020
A. Boldyrev, D. Derkach, M. Hushchyn et al., Physical Review D - Particles, Fields, Gravitation and Cosmology 2019 Vol. 100 No. 11 P. 112006-1-112006-17
The production fraction of the B−c meson with respect to the sum of B− and ¯B0 mesons is measured in both 7 and 13 TeV center-of-mass (c.m.) energy pp collisions produced by the Large Hadron Collider (LHC), using the LHCb detector. The rate, approximately 3.7 per mille, does not change with energy, but shows a transverse momentum dependence. The B−c−B+c production asymmetry is also measured and is ...
Added: February 20, 2020
LHCb C., A. Boldyrev, D. Derkach et al., Chinese Physics C 2020 Vol. 44 No. 2 Article 022001
The production of Ξ++cc baryons in proton-proton collisions at a centre-of-mass energy of s√=13 TeV is measured in the transverse-momentum range 4<pT<15 GeV/c and the rapidity range 2.0<y<4.5. The data used in this measurement correspond to an integrated luminosity of 1.7 fb−1, recorded by the LHCb experiment during 2016. The ratio of the Ξ++cc production cross-section times the branching fraction of the Ξ++cc→Λ+cK−π+π+ decay relative to the prompt Λ+c production ...
Added: September 16, 2020
Aaij R., Beteta C. A., Arzymatov K. et al., Journal of High Energy Physics 2020 Vol. 2020 No. 12 P. 1-31
The shape of the 𝐵0𝑠→𝐷∗−𝑠𝜇+𝜈𝜇 differential decay rate is obtained as a function of the hadron recoil parameter using proton-proton collision data at a centre-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 1.7 fb−1 collected by the LHCb detector. The 𝐵0𝑠→𝐷∗−𝑠𝜇+𝜈𝜇 decay is reconstructed through the decays 𝐷∗−𝑠→𝐷−𝑠𝛾 and 𝐷−𝑠→𝐾−𝐾+𝜋−. The differential decay rate is fitted with ...
Added: September 1, 2021
Aaij R., Beteta C. A., Arzymatov K. et al., Physical Review Letters 2020 Vol. 125 No. 21 P. 1-13
Added: December 2, 2020
Aaij R., Beteta C. A., A. Boldyrev et al., Journal of High Energy Physics 2020 Vol. 11 No. 095 P. 1-20
A search for the doubly heavy {\Xi}_{bc}^0Ξbc0 baryon using its decay to the D^{0}0pK^{–}– final state is performed using proton-proton collision data at a centre-of-mass energy of 13 TeV collected by the LHCb experiment between 2016 and 2018, corresponding to an integrated luminosity of 5.4 fb^{−1}−1. No significant signal is found in the invariant mass range from 6.7 ...
Added: December 2, 2020
Aaij R., Arzymatov K., Belavin V. et al., Science Bulletin 2021 Vol. 66 No. 13 P. 1278-1287
First evidence of a structure in the J/ψΛ invariant mass distribution is obtained from an amplitude analysis of Ξb-→J/ψΛK- decays. The observed structure is consistent with being due to a charmonium pentaquark with strangeness with a significance of 3.1σ including systematic uncertainties and look-elsewhere effect. Its mass and width are determined to be 4458.8±2.9-1.1+4.7MeV and 17.3±6.5-5.7+8.0MeV, respectively, where the quoted uncertainties are statistical ...
Added: August 28, 2021
Aaij R., A. Boldyrev, D. Derkach et al., Physical Review D - Particles, Fields, Gravitation and Cosmology 2020 Vol. 101 No. 1 Article 012006
The results of an amplitude analysis of the charmless three-body decay B+→π+π+π-, in which CP-violation effects are taken into account, are reported. The analysis is based on a data sample corresponding to an integrated luminosity of 3 fb-1 of pp collisions recorded with the LHCb detector. The most challenging aspect of the analysis is the description ...
Added: December 7, 2020
Aaij R., Arzymatov K., Belavin V. et al., Physical Review Letters 2021 Vol. 126 No. 9 Article 091802
A measurement of CP violation in the decay B+→K+π0 is reported using data corresponding to an integrated luminosity of 5.4 fb−1 collected with the LHCb experiment at a center-of-mass energy of √s=13 TeV. The CP asymmetry is measured to be 0.025±0.015±0.006±0.003, where the uncertainties are statistical, systematic, and due to an external input. This is the most precise measurement of this quantity. It confirms and significantly enhances ...
Added: August 28, 2021
Aaij R., Beteta C. A., Arzymatov K. et al., Journal of High Energy Physics 2021 Vol. 2021 No. 3 P. 1-18
A search for the Bs0 → D*±D∓ decay is performed using proton-proton collision data at centre-of-mass energies of 7, 8 and 13 TeV collected by the LHCb experiment, corresponding to an integrated luminosity of 9 fb−1. The decay is observed with a high significance and its branching fraction relative to the B0 → D*±D∓ decay is measured to be
B(Bs0→D∗±D∓)/(B0→D∗±D∓)=0.137±0.017±0.002±0.006,
where the first ...
Added: August 28, 2021
A Maevskiy, D Derkach, N Kazeev et al., Journal of Physics: Conference Series 2020 Vol. 1525 No. 012097 P. 1-6
The increasing luminosities of future Large Hadron Collider runs and next generation of collider experiments will require an unprecedented amount of simulated events to be produced. Such large scale productions are extremely demanding in terms of computing resources. Thus new approaches to event generation and simulation of detector responses are needed. In LHCb, the accurate ...
Added: July 27, 2020
A. S. Maevskiy, A. S. Boldyrev, ATLAS C., Journal of High Energy Physics 2018 Vol. 10 No. 047 P. 1-46
An angular analysis of the decay Bd0 → K∗μ+μ− is presented, based on proton-proton collision data recorded by the ATLAS experiment at the LHC. The study is using 20.3 fb−1 of integrated luminosity collected during 2012 at centre-of-mass energy of √s = 8 TeV. Measurements of the K* longitudinal polarisation fraction and a set of angular parameters obtained for this decay are presented. The ...
Added: March 1, 2019
Aaij R., Abdelmotteleb A. S., Abellán Beteta C. et al., Physical Review D - Particles, Fields, Gravitation and Cosmology 2022 Vol. 105 No. 9 Article 092013
A measurement of the ratios of the effective decay widths of D0 → π−πþ and D0 → K−Kþ decays over that of D0 → K−πþ decays is performed with the LHCb experiment using proton–proton collisions at a centre-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 6 fb−1. These observables give access to ...
Added: December 29, 2022
Derkach D., Hushchyn M., Kazeev N. et al., Physical Review Letters 2019 Vol. 123 No. 3 P. 1-11
The radiative decay Λ0b→Λγ is observed for the first time using a data sample of proton-proton collisions corresponding to an integrated luminosity of 1.7 fb−1 collected by the LHCb experiment at a center-of-mass energy of 13 TeV. Its branching fraction is measured exploiting the B0→K*0γ decay as a normalization mode and is found to be B(Λ0b→Λγ)=(7.1±1.5±0.6±0.7)×10−6, where the quoted uncertainties are statistical, systematic, and ...
Added: March 16, 2020
Aaij R., Abdelmotteleb A. S., Abellan Beteta C. et al., Physical Review D - Particles, Fields, Gravitation and Cosmology 2023 Vol. 108 No. 1 Article 12007
A search for the rare hadronic decay B0s→p¯p is performed using proton-proton collision data recorded by the LHCb experiment at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 6 fb−1. No evidence of the decay is found and an upper limit on its branching fraction is set at B(B0s→p¯p)<4.4(5.1)×10−9 at 90% (95%) confidence level; this is currently the ...
Added: September 1, 2023
Aaij R., Abdelmotteleb A. S., Abellán Beteta C. et al., Physical Review Letters 2022 Vol. 129 No. 9 Article 091801
The first study of the angular distribution of μþμ− pairs produced in the forward rapidity region via the Drell-Yan reaction pp → γ=Z þ X → lþl− þ X is presented, using data collected with the LHCb detector at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 5.1 fb−1. The coefficients ...
Added: December 29, 2022
Aaij R., Abdelmotteleb A. S., Abellán Beteta C. et al., Journal of High Energy Physics 2022 Vol. 2022 No. 5 Article 38
The Ξ++ → Ξ′+π+ decay is observed using proton-proton collisions collected by the LHCb experiment at a centre-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 5.4fb−1. The Ξ++ → Ξ′+π+ decay is reconstructed partially, where the photon from the Ξ′+ → Ξ+γ decay is not reconstructed and the pK−π+ final state of the ...
Added: December 30, 2022
Derkach D., Hushchyn M., Kazeev N. et al., Journal of High Energy Physics 2019 Vol. 6 P. 1-27
The first untagged decay-time-integrated amplitude analysis of Bs0 → KS0K±π∓ decays is performed using a sample corresponding to 3.0 fb−1 of pp collision data recorded with the LHCb detector during 2011 and 2012. The data are described with an amplitude model that contains contributions from the intermediate resonances K*(892)0,+, K2*(1430)0,+ and K0*(1430)0,+, and their charge conjugates. Measurements of the branching fractions of the decay modes Bs0 → K*(892)±K∓ and 𝐵0𝑠→𝐾∗(---)(892)0𝐾0(---)Bs0→K∗(---)(892)0K0(---) are in ...
Added: March 16, 2020
Aaij R., Abellán Beteta C., Ackernley T. et al., Chinese Physics C 2021 Vol. 45 No. 9 Article 093002
The first search for the doubly heavy Ω0bc baryon and a search for Ξ0bc baryon are performed using pp collision data collected via the LHCb experiment from 2016 to 2018 at a centre-of-mass energy of 13TeV, corresponding to an integrated luminosity of 5.2fb−1. The baryons are reconstructed via their decays to Λ+cπ− and Ξ+cπ−. No significant excess is found for invariant masses between 6700 and ...
Added: March 18, 2022
Егоров Е. А., Rogachev A., Доклады Российской академии наук. Математика, информатика, процессы управления (ранее - Доклады Академии Наук. Математика) 2023 Т. 514 № 2 С. 49-59
When using Wasserstein GAN loss function for training generative adversarial networks (GAN), it is theoretically necessary to limit the discriminators’ expressive power (so called discriminator normalization). Such limitation increases the stability of GAN training at the expense of a less expressive final model. Spectral normalization is one of the normalization algorithms that involves applying a ...
Added: November 30, 2023