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Search for the doubly charmed baryon Ξ cc
Science China Physics, Mechanics & Astronomy. 2020. Vol. 63. No. 2. Article 221062.
A search for the doubly charmed baryon Ξ cc is performed through its decay to the Λ + c K − π + final state, using proton-proton collision data collected with the LHCb detector at centre-of-mass energies of 7, 8 and 13 TeV. The data correspond to a total integrated luminosity of 9 fb −1 . No significant signal is observed in the mass range from 3.4 to 3.8 GeV/c 2 . Upper limits are set at 95% credibility level on the ratio of the Ξ cc production cross-section times the branching fraction to that of Λ + c and Ξ cc
baryons. The limits are determined as functions of the Ξ cc mass for different lifetime hypotheses, in the rapidity range from 2.0 to 4.5 and the transverse momentum range from 4 to 15 GeV/c.
LHCb C., Arzymatov K., Belavin V. et al., The European Physical Journal C - Particles and Fields 2021 Vol. 81 No. 11 Article 1026
A flavour-tagged time-dependent angular analysis of {{B} ^0_{s}} \!\rightarrow {{J /\psi }} \phi decays is presented where the {J /\psi } meson is reconstructed through its decay to an e ^+e ^- pair. The analysis uses a sample of pp collision data recorded with the LHCb experiment at centre-of-mass energies of 7 and 8\text {\,Te ...
Added: February 18, 2022
Borisyak M., Derkach D., Ustyuzhanin A. et al., The European Physical Journal C - Particles and Fields 2017 Vol. 77 No. 9 P. 609-626
Using decays to ϕ-meson pairs, the inclusive production of charmonium states in b-hadron decays is studied with pp collision data corresponding to an integrated luminosity of 3.0fb−1, collected by the LHCb experiment at centre-of-mass energies of 7 and 8 TeV. Denoting by BC≡B(b→CX)×B(C→ϕϕ) the inclusive branching fraction of a b hadron to a charmonium state ...
Added: October 23, 2017
LHCb C., Aaij R., Arzymatov K. et al., Journal of High Energy Physics 2020 Vol. 12 Article 81
An angular analysis of the B0 → K*0e+e− decay is performed using a data sample corresponding to an integrated luminosity of 9 fb−1 of pp collisions collected with the LHCb experiment. The analysis is conducted in the very low dielectron mass squared (q2) interval between 0.0008 and 0.257 GeV2, where the rate is dominated by the B0 → K*0γ transition with a virtual photon. The fraction ...
Added: September 1, 2021
Aaij R., Beteta C. A., Arzymatov K. et al., Journal of High Energy Physics 2021 Vol. 2021 No. 2 Article 169
A measurement of CP-violating observables is performed using the decays B± → DK± and B± → Dπ±, where the D meson is reconstructed in one of the self-conjugate three-body final states 𝐾0SKS0π+π− and 𝐾0SKS0K+K− (commonly denoted 𝐾0SKS0h+h−). The decays are analysed in bins of the D-decay phase space, leading to a measurement that is independent of the modelling of the D-decay amplitude. The observables are inter- preted in terms of the CKM ...
Added: September 1, 2021
Hushchyn M., Derkach D., Ustyuzhanin A. et al., Physics Letters B 2018 Vol. 777 P. 16-30
Measurements of CP observables in B±→D(⁎)K± and B±→D(⁎)π± decays are presented, where D(⁎) indicates a neutral D or D⁎ meson that is an admixture of D(⁎)0 and D¯(⁎)0states. Decays of the D⁎ meson to the Dπ0 and Dγ final states are partially reconstructed without inclusion of the neutral pion or photon, resulting in distinctive shapes in the Bcandidate invariant mass distribution. Decays of the D meson are fully reconstructed in the K±π∓, K+K− and π+π− final states. The analysis uses a sample of charged B mesons ...
Added: January 30, 2018
Aaij R., Beteta C. A., Boldyrev A. et al., Physical Review D - Particles, Fields, Gravitation and Cosmology 2020 Vol. 102 No. 5 P. 051101
A search for CP violation in the Λ0b→pπ−π+π− decay is performed using LHCb data corresponding to an integrated luminosity of 6.6 fb−1 collected in pp collisions at center-of-mass energies of 7, 8 and 13 TeV. The analysis uses both triple product asymmetries and the unbinned energy test method. The highest significances of CP asymmetry are 2.9 standard ...
Added: September 16, 2020
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
Derkach D., Hushchyn M., Kazeev N. et al., Physical Review Letters 2019 Vol. 123 No. 23 P. 231802
The first amplitude analysis of the B±→π±K+K− decay is reported based on a data sample corresponding to an integrated luminosity of 3.0 fb−1 of pp collisions recorded in 2011 and 2012 with the LHCb detector. The data are found to be best described by a coherent sum of five resonant structures plus a nonresonant component and ...
Added: March 12, 2020
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
Borisyak M., Ustyuzhanin A., Derkach D. et al., Journal of Physics: Conference Series 2017 No. 898 P. 1-7
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: June 16, 2017
Aaij R., Arzymatov K., Belavin V. et al., Physical Review D - Particles, Fields, Gravitation and Cosmology 2020 Vol. 102 No. 11 Article 112010
The relative branching fractions of B+→h+h'+h'− decays, where h(') is a pion or kaon, are measured. The analysis is performed with a data sample, collected with the LHCb detector, corresponding to an integrated luminosity of 3.0 fb−1 of pp collisions. The results obtained improve significantly on previous measurements of these quantities, and are important for the interpretation of Dalitz plot analyses of three-body charmless ...
Added: September 1, 2021
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
Ryzhikov A., Ustyuzhanin A., Journal of Physics: Conference Series 2018 Vol. 1085 P. 1-6
In the research, a new approach for finding rare events in high-energy physics was tested. As an example of physics channel the decay of \tau -> 3 \mu is taken that has been published on Kaggle within LHCb-supported challenge. The training sample consists of simulated signal and real background, so the challenge is to train ...
Added: December 11, 2017
M. Borisyak, N. Kazeev, Journal of Instrumentation 2019 Vol. 14 No. 08 P. 1-8
Data analysis in high energy physics often deals with data samples consisting of a mixture of signal and background events. The sPlot technique is a common method to subtract the contribution of the background by assigning weights to events. Part of the weights are by design negative. Negative weights lead to the divergence of some ...
Added: August 20, 2019
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
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., 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
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
Borisyak M., Kazeev N., Journal of Physics: Conference Series 2020 Vol. 1525 Article 012088
Data analysis in high energy physics has to deal with data samples produced from different sources. One of the most widely used ways to unfold their contributions is the sPlot technique. It uses the results of a maximum likelihood fit to assign weights to events. Some weights produced by sPlot are by design negative. Negative ...
Added: October 5, 2021
Aaij R., Beteta C. A., Boldyrev A. et al., Physical Review D - Particles, Fields, Gravitation and Cosmology 2020 Vol. 102 No. 1 P. 012011
A measurement of the branching fraction of the decay B0s→K0SK0S is performed using proton–proton collision data corresponding to an integrated luminosity of 5 fb−1 collected by the LHCb experiment between 2011 and 2016. The branching fraction is determined to be B(B0s→K0SK0S)=[8.3±1.6(stat)±0.9(syst)±0.8(norm)±0.3(fs/fd)]×10−6, where the first uncertainty is statistical, the second is systematic, and the third and fourth ...
Added: September 16, 2020
Ustyuzhanin A., Likhomanenko T., Derkach D. et al., Journal of Instrumentation 2016 Vol. 11
A new algorithm for the determination of the initial flavour of B0 s mesons is presented. The algorithm is based on two neural networks and exploits the b hadron production mechanism at a hadron collider. The first network is trained to select charged kaons produced in association with the B0 s meson. The second network ...
Added: October 23, 2016
LHCb C., Derkach D., Hushchyn M. et al., The European Physical Journal C - Particles and Fields 2020 Vol. 80 No. 3 Article 185
The cross-sections of 𝜓(2𝑆)ψ(2S) meson production in proton-proton collisions at 𝑠√=13 TeVs=13 TeV are measured with a data sample collected by the LHCb detector corresponding to an integrated luminosity of 275 pb−1275 pb−1. The production cross-sections for prompt 𝜓(2𝑆)ψ(2S) mesons and those for 𝜓(2𝑆)ψ(2S) mesons from b-hadron decays (𝜓(2𝑆)-from- 𝑏ψ(2S)-from- b) are determined as functions of the transverse momentum, 𝑝TpT, and the rapidity, y, of the 𝜓(2𝑆)ψ(2S) meson in the kinematic range 2<𝑝T<20 GeV/𝑐2<pT<20 GeV/c and 2.0<𝑦<4.52.0<y<4.5. The production cross-sections ...
Added: December 7, 2020
Hushchyn M., Derkach D., Ustyuzhanin A. et al., Nature Physics 2017 Vol. 13 P. 391-396
Differences in the behaviour of matter and antimatter have been observed in K and B meson decays, but not yet in any baryon decay. Such differences are associated with the non-invariance of fundamental interactions under the combined charge-conjugation and parity transformations, known as CP violation. Here, using data from the LHCb experiment at the Large Hadron Collider, we search for CP-violating asymmetries ...
Added: January 30, 2018