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Angular Analysis of the B+→K*+μ+μ− Decay
Physical Review Letters. 2021. Vol. 126. No. 16. Article 161802.
Aaij R., Arzymatov K., Belavin V., Boldyrev A., Borisyak M., Derkach D., Hushchyn M., Kazeev N., Maevskiy A., Philippov A., Popov S., Ratnikov F., Ryzhikov A., Ustyuzhanin A., Zunica G.
We present an angular analysis of the Bþ → Kþð→ K0SπþÞμþμ− decay using 9 fb−1 of pp collision data collected with the LHCb experiment. For the first time, the full set of CP-averaged angular observables is measured in intervals of the dimuon invariant mass squared. Local deviations from standard model predictions are observed, similar to those in previous LHCb analyses of the isospin-partner B0 → K0μþμ− decay. The global tension is dependent on which effective couplings are considered and on the choice of theory nuisance parameters.
Publication based on the results of:
Aaij R., Beteta C. A., Arzymatov K. et al., Physical Review Letters 2021 Vol. 127 No. 8 Article 082001
The first observation of exotic states with a new quark content cc ̄us ̄ decaying to the J=ψKþ final state is reported with high significance from an amplitude analysis of the Bþ → J=ψφKþ decay. The analysis is carried out using proton-proton collision data corresponding to a total integrated luminosity of 9 fb−1 collected by the LHCb experiment at center-of-mass energies of 7, 8, and 13 TeV. The most significant state, Z ð4000Þþ, ...
Added: August 28, 2021
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., 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
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
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
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., 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
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
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., 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
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
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
Ahdida C., Albanese R., Alexandrov A. et al., Journal of Instrumentation 2020 Vol. 15 Article P01027
The Search for Hidden Particles (SHiP) experiment proposal at CERN demands a dedicated dipole magnet for its scattering and neutrino detector. This requires a very large volume to be uniformly magnetized at B>1.2 T, with constraints regarding the inner instrumented volume as well as the external region, where no massive structures are allowed and only an ...
Added: October 14, 2021
Aaij R., Belavin V., Boldyrev A. et al., Physics Letters B 2021 No. 815 Article 136172
The Λ0b→Λ+cK+K−π−Λb0→Λc+K+K−π− decay is observed for the first time using a data sample of proton-proton collisions at centre-of-mass energies of s√=7s=7 and 8 TeVTeV collected by the LHCbLHCb detector, corresponding to an integrated luminosity of 3fb−13fb−1. The ratio of branching fractions between the Λ0b→Λ+cK+K−π−Λb0→Λc+K+K−π− and the Λ0b→Λ+cD−sΛb0→Λc+Ds− decays is measured to be
B(Λ0b→Λ+cK+K−π−)B(Λ0b→Λ+cD−s)=(9.26±0.29±0.46±0.26)×10−2,B(Λb0→Λc+K+K−π−)B(Λb0→Λc+Ds−)=(9.26±0.29±0.46±0.26)×10−2,
where the first uncertainty is statistical, the second systematic and the third is due to the knowledge ...
Added: August 31, 2021
A S Boldyrev, A Maevsky, Journal of Physics: Conference Series 2017 Vol. 798 No. 1 P. 1-5
Operating conditions and challenging demands of present and future accelerator experiments result in new requirements on detector systems. There are many ongoing activities aimed to develop new technologies and to improve the properties of detectors based on existing technologies. Our work is dedicated to development of Transition Radiation Detectors (TRD) suitable for different applications. In ...
Added: January 30, 2019
Aaij R., Beteta C. A., Boldyrev A. et al., The European Physical Journal C - Particles and Fields 2021 Vol. 81 No. 261 P. 1-16
Long-lived particles decaying to e±μ∓νe±μ∓ν, with masses between 7 and 5050 GeV/c22 and lifetimes between 2 and 5050 ps, are searched for by looking at displaced vertices containing electrons and muons of opposite charges. The search is performed using 5.45.4 fb−1−1 of pppp collisions collected with the LHCb detector at a centre-of-mass energy of s√=13s=13 TeV. Three mechanisms of production of long-lived particles are considered: the direct pair ...
Added: August 31, 2021
Aaij R., Arzymatov K., Belavin V. et al., Journal of High Energy Physics 2021 Vol. 5 Article 95
The Cabibbo-suppressed decay Λ0b → χc1pπ− is observed for the first time us- ing data from proton-proton collisions corresponding to an integrated luminosity of 6 fb−1, collected with the LHCb detector at a centre-of-mass energy of 13 TeV. Evidence for the Λ0b → χc2pπ− decay is also found. Using the Λ0b → χc1pK− decay as normalisation channel, the ratios of branching fractions are measured to be... where the first uncertainty is statistical, ...
Added: August 28, 2021
Ahdida C., Ratnikov F., Ustyuzhanin A. et al., The European Physical Journal C - Particles and Fields 2020 Vol. 80 Article 284
The SHiP experiment is proposed to search for very weakly interacting particles beyond the Standard Model which are produced in a 400 GeV/c proton beam dump at the CERN SPS. About 10^11 muons per spill will be produced in the dump. To design the experiment such that the muon-induced background is minimized, a precise knowledge of the ...
Added: October 14, 2021
Ratnikov F., Journal of High Energy Physics 2018 Vol. 1811 P. 1-35
The production of ϒ(nS) mesons (n = 1, 2, 3) in pPb and Pbp collisions at a centre-of-mass energy per nucleon pair 𝑠NN‾‾‾‾√=8.16sNN=8.16 TeV is measured by the LHCb experiment, using a data sample corresponding to an integrated luminosity of 31.8 nb−1−1. The ϒ(nS) mesons are reconstructed through their decays into two opposite-sign muons. The measurements comprise ...
Added: March 11, 2019
Ratnikov F., Journal of High Energy Physics 2018 Vol. 1808 P. 1-19
The 𝐵0𝑠⎯⎯⎯⎯⎯⎯⎯→𝜒𝑐2𝐾+𝐾−Bs0¯→χc2K+K− decay mode is observed and its branching fraction relative to the corresponding 𝜒𝑐1χc1decay mode, in a ±15MeV/𝑐2±15MeV/c2 window around the 𝜙ϕ mass, is found to be (𝐵0𝑠⎯⎯⎯⎯⎯⎯⎯→𝜒𝑐2𝐾+𝐾−)(𝐵0𝑠⎯⎯⎯⎯⎯⎯⎯→𝜒𝑐1𝐾+𝐾−)=(17.1±3.1±0.4±0.9)%,B(Bs0¯→χc2K+K−)B(Bs0¯→χc1K+K−)=(17.1±3.1±0.4±0.9)%, where the first uncertainty is statistical, the second systematic and the third due to the knowledge of the branching fractions of radiative 𝜒𝑐χc decays. The decay mode 𝐵0𝑠⎯⎯⎯⎯⎯⎯⎯→𝜒𝑐1𝐾+𝐾−Bs0¯→χc1K+K− allows the 𝐵0𝑠Bs0 mass to be measured as 𝑚(𝐵0𝑠)=5366.83±0.25±0.27MeV/𝑐2,m(Bs0)=5366.83±0.25±0.27MeV/c2,where the first uncertainty is statistical ...
Added: March 11, 2019
Ratnikov F., Physical Review Letters 2018 Vol. 121 No. 22 P. 222001-1-222001-10
The cross section for prompt antiproton production in collisions of protons with an energy of 6.5 TeV incident on helium nuclei at rest is measured with the LHCb experiment from a data set corresponding to an integrated luminosity of 0.5 nb-1. The target is provided by injecting helium gas into the LHC beam line at the LHCb ...
Added: March 11, 2019
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
A S Boldyrev, A Maevsky, Journal of Physics: Conference Series 2017 Vol. 798 No. 1 P. 1-5
Towards the end of LHC Run1, gas leaks were observed in some parts of the Transition Radiation Tracker (TRT) of ATLAS. Due to these leaks, primary Xenon based gas mixture was replaced with Argon based mixture in various parts. Test-beam studies with a dedicated Transition Radiation Detector (TRD) prototype were carried out in 2015 in ...
Added: January 30, 2019
Ratnikov F., The European Physical Journal C - Particles and Fields 2018 Vol. 78 No. 12 P. 1-12
A search is presented for a Higgs-like boson with mass in the range 45 to 195 GeV/𝑐2GeV/c2 decaying into a muon and a tau lepton. The dataset consists of proton-proton interactions at a centre-of-mass energy of 8 TeV TeV , collected by the LHCb experiment, corresponding to an integrated luminosity of 2 fb −1 fb −1 . The tau leptons are reconstructed in both leptonic ...
Added: March 10, 2019