Search for CP violation in B^0 -> J/psi K^0_S decays with first LHCb data

We report a measurement of the CP violation in B^0 -> J/\psi K^0_S decays. We perform a time-dependent analysis of the decays reconstructed in 35/pb of LHCb data that was taken in 2010. We measure the CP asymmetry parameterComment: Presented at the 2011 Hadron Collider Physics symposium (HCP-2011), Paris, France, November 14-18 2011, 3 pages, 3 figure

LHCb: Outer Tracker

The LHCb Outer Tracker Detector Design & Productio

LHCb: Beam Pipe

The proton beams circulate in the accelerator in Ultra High Vacuum to make them interact only with each other when colliding at the interaction point. A special beam pipe "holds" the vacuum where they pass through the LHCb detector:it has to be mechanically very strong to stand the difference in pressure between the vacuum inside it and the air in the cavern but also be as transparent as possible for the particles originating in the proton−proton collisions

LHCb: Silicon Tracker

Design of the LHCb Silicon Tracker and the Common Tell1 boar

LHCb: Inner Tracker

The LHCb Inner Tracke

Study of coherent charmonium production in ultra-peripheral lead-lead collisions

The cross-sections of coherent $J/\psi$ and $\psi(\mathrm{2S})$ production in ultra-peripheral PbPb collisions at a nucleon-nucleon centre-of-mass energy of $5.02\,\mathrm{TeV}$ are measured using a data sample corresponding to an integrated luminosity of $228\pm10\,\mathrm{\mu b}^{-1}$, collected by the LHCb experiment in 2018. The differential cross-sections are measured separately as a function of transverse momentum and rapidity in the nucleus-nucleus centre-of-mass frame for $J/\psi$ and $\psi(\mathrm{2S})$ mesons. The integrated cross-sections are measured to be $\sigma^\mathrm{coh}_{J/\psi} = 5.965 \pm 0.059 \pm 0.232 \pm 0.262\,\mathrm{mb}$ and $\sigma^\mathrm{coh}_{\psi(\mathrm{2S})} = 0.923 \pm 0.086 \pm 0.028 \pm 0.040\,\mathrm{mb}$, where the first listed uncertainty is statistical, the second systematic and the third due to the luminosity determination. The cross-section ratio is measured to be $\sigma^\mathrm{coh}_{\psi(\mathrm{2S})}/\sigma^\mathrm{coh}_{J/\psi} = 0.155 \pm 0.014 \pm 0.003$, where the first uncertainty is statistical and the second is systematic. These results are compatible with theoretical predictions.Comment: All figures and tables, along with any supplementary material and additional information, are available at https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2022-012.html (LHCb public pages

A study of C ⁣PC\!P violation in the decays B±→[K+K−π+π−]Dh±B^\pm\to[K^+K^-\pi^+\pi^-]_D h^{\pm} (h=K,πh = K, \pi) and B±→[π+π−π+π−]Dh±B^\pm\to[\pi^+\pi^-\pi^+\pi^-]_D h^{\pm}

The first study of $C\!P$ violation in the decay mode $B^\pm\to[K^+K^-\pi^+\pi^-]_D h^\pm$, with $h=K,\pi$, is presented, exploiting a data sample of proton-proton collisions collected by the LHCb experiment that corresponds to an integrated luminosity of $9$ fb$^{-1}$. The analysis is performed in bins of phase space, which are optimised for sensitivity to local $C\!P$ asymmetries. $C\!P$-violating observables that are sensitive to the angle $\gamma$ of the Unitarity Triangle are determined. The analysis requires external information on charm-decay parameters, which are currently taken from an amplitude analysis of LHCb data, but can be updated in the future when direct measurements become available. Measurements are also performed of phase-space integrated observables for $B^\pm\to[K^+K^-\pi^+\pi^-]_D h^\pm$ and $B^\pm\to[\pi^+\pi^-\pi^+\pi^-]_D h^\pm$ decays.Comment: All figures and tables, along with any supplementary material and additional information, are available at https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2022-037.html (LHCb public pages

LHCb: an international research facility

Research facilit