Review of recent LHCb results and prospects for Run II

As first Run II data acquisition has begun, it is useful to expose the pending questions by reviewing some of the most recent results obtained with Run I data analyses. Early results of the current data taking and middle-term prospects are also shown to illustrate the efficiency of the acquisition and analysis chain.Comment: 8 pages, 12 figures, proceedings of the LISHEP (International School of High Energy Physics) 2015 conference, Manaus, 02-08 August 201

Alignment of LHCb tracking stations with tracks fitted with a Kalman filter

The LHCb detector, operating at the Large Hadron Collider at CERN, is a single arm spectrometer optimized for the detection of the forward b anti-b production for b physics studies. The reconstruction of vertices and tracks is done by silicon micro-strips and gaseous straw-tube based detectors. In order to achieve good mass resolution for resonances the tracking detectors should be aligned to a precision of the order of ten microns. A software framework has been developed to achieve these goals and has been tested in various configurations. After a description of the software, we present alignment results and show in particular for the first time that a global $\chi^2$ solving for alignment using a locally parameterized track trajectory can be achieved

First studies of T-station alignment with simulated data

The alignment of the tracking stations using tracks fitted using standard LHCb track fit is studied. The procedure is presented together with two examples using simulated data. The first scenario presents the alignment of the IT and OT layers using beam-gas events at 450~GeV with no magnetic field. The second scenario is the alignment of the OT layers and IT boxes, layers and ladders with magnet-on data using minimum bias events at nominal energy. The results are validated by refitting J/$\psi$ tracks using the misaligned geometry compared to the re-aligned case as well as the default. It is shown that after alignment the J $\psi$ mass resolution is degraded by at most 3~\%

LHCb: Status and Prospects on the bb Anomalies

{Since the start of the Large Hadron Collider program, direct searches for Beyond Standard Model (BSM) particles have constrained their mass scale to limits which are now above the energy reach of the current collider. As a result, studies of indirect probes of BSM physics have gained a considerable momentum, both experimentally and theoretically. The flavour anomalies in $b$ hadron decays are now recognized as an important laboratory for the indirect detection of BSM physics. This short review presents several key analyses in this area, and some prospects with future data.Comment: Submitted as a proceeding of the 19th International Conference on B-Physics at Frontier Machines, BEAUTY 2020, Kashiwa, Japan (online). arXiv admin note: substantial text overlap with arXiv:1910.1312

Flavour anomalies in BB decays at LHCb

The direct searches for Beyond Standard Model (BSM) particles have been constraining their mass scale to the extent where it is now becoming consensual that such particles are likely to be above the energy reach of the LHC. Meanwhile, the studies of indirect probes of BSM physics, with all their diversity, have been progressing both in accurracy and in setting up observables with reduced theoretical uncertainties. The observation of flavour anomalies in $b$ hadron decays represents an important part of the program of indirect detection of BSM physics. Several benchmark analyses involving leptonic or semileptonic decays are presented, with an emphasis on intriguing patterns which are systematic in their trend, though not individually significant yet.Comment: 5 pages. Proceedings of the 21st international workshop on neutrinos from accelerators (NuFact2019), August 26 - August 31, 2019, Daegu, Kore

New Physics Search at LHCB

Although direct detection of new particles will be the main focus of the LHC, indirect New Physics searches are expected to provide useful complementary information. In particular, precision measurements of rare processes occurring in flavour physics are of utmost importance in constraining the structure of the New physics low energy effective Lagrangian. In this paper, few key LHCb studies, including $B_s-\bar{B}_s$ mixing and rare decays through the quark level $b\to s$ loop transition, are presented to illustrate New Physics effects at low energy.Comment: Proceeding of Moriond QCD 2008, 5 page

Observation of the decay Bc→J/ψK+K−π+B_c \rightarrow J/\psi K^+ K^- \pi^+

The decay $B_c\rightarrow J/\psi K^+ K^- \pi^+$ is observed for the first time, using proton-proton collisions collected with the LHCb detector corresponding to an integrated luminosity of 3fb$^{-1}$. A signal yield of $78\pm14$ decays is reported with a significance of 6.2 standard deviations. The ratio of the branching fraction of \B_c \rightarrow J/\psi K^+ K^- \pi^+ decays to that of $B_c \rightarrow J/\psi \pi^+$ decays is measured to be $0.53\pm 0.10\pm0.05$, where the first uncertainty is statistical and the second is systematic.Comment: 18 pages, 2 figure

Observation of J/ψpJ/\psi p resonances consistent with pentaquark states in Λb0→J/ψK−p{\Lambda_b^0\to J/\psi K^-p} decays

Observations of exotic structures in the $J/\psi p$ channel, that we refer to as pentaquark-charmonium states, in $\Lambda_b^0\to J/\psi K^- p$ decays are presented. The data sample corresponds to an integrated luminosity of 3/fb acquired with the LHCb detector from 7 and 8 TeV pp collisions. An amplitude analysis is performed on the three-body final-state that reproduces the two-body mass and angular distributions. To obtain a satisfactory fit of the structures seen in the $J/\psi p$ mass spectrum, it is necessary to include two Breit-Wigner amplitudes that each describe a resonant state. The significance of each of these resonances is more than 9 standard deviations. One has a mass of $4380\pm 8\pm 29$ MeV and a width of $205\pm 18\pm 86$ MeV, while the second is narrower, with a mass of $4449.8\pm 1.7\pm 2.5$ MeV and a width of $39\pm 5\pm 19$ MeV. The preferred $J^P$ assignments are of opposite parity, with one state having spin 3/2 and the other 5/2.Comment: 48 pages, 18 figures including the supplementary material, v2 after referee's comments, now 19 figure

Study of Bc+B_c^+ decays to the K+K−π+K^+K^-\pi^+ final state and evidence for the decay Bc+→χc0π+B_c^+\to\chi_{c0}\pi^+

A study of $B_c^+\to K^+K^-\pi^+$ decays is performed for the first time using data corresponding to an integrated luminosity of 3.0 $\mathrm{fb}^{-1}$ collected by the LHCb experiment in $pp$ collisions at centre-of-mass energies of $7$ and $8$ TeV. Evidence for the decay $B_c^+\to\chi_{c0}(\to K^+K^-)\pi^+$ is reported with a significance of 4.0 standard deviations, resulting in the measurement of $\frac{\sigma(B_c^+)}{\sigma(B^+)}\times\mathcal{B}(B_c^+\to\chi_{c0}\pi^+)$ to be $(9.8^{+3.4}_{-3.0}(\mathrm{stat})\pm 0.8(\mathrm{syst}))\times 10^{-6}$. Here $\mathcal{B}$ denotes a branching fraction while $\sigma(B_c^+)$ and $\sigma(B^+)$ are the production cross-sections for $B_c^+$ and $B^+$ mesons. An indication of $\bar b c$ weak annihilation is found for the region $m(K^-\pi^+)<1.834\mathrm{\,Ge\kern -0.1em V\!/}c^2$, with a significance of 2.4 standard deviations.Comment: All figures and tables, along with any supplementary material and additional information, are available at https://lhcbproject.web.cern.ch/lhcbproject/Publications/LHCbProjectPublic/LHCb-PAPER-2016-022.html, link to supplemental material inserted in the reference

Measurement of the mass and lifetime of the Ωb−\Omega_b^- baryon

A proton-proton collision data sample, corresponding to an integrated luminosity of 3 fb$^{-1}$ collected by LHCb at $\sqrt{s}=7$ and 8 TeV, is used to reconstruct $63\pm9$ $\Omega_b^-\to\Omega_c^0\pi^-$, $\Omega_c^0\to pK^-K^-\pi^+$ decays. Using the $\Xi_b^-\to\Xi_c^0\pi^-$, $\Xi_c^0\to pK^-K^-\pi^+$ decay mode for calibration, the lifetime ratio and absolute lifetime of the $\Omega_b^-$ baryon are measured to be \begin{align*} \frac{\tau_{\Omega_b^-}}{\tau_{\Xi_b^-}} &= 1.11\pm0.16\pm0.03, \\ \tau_{\Omega_b^-} &= 1.78\pm0.26\pm0.05\pm0.06~{\rm ps}, \end{align*} where the uncertainties are statistical, systematic and from the calibration mode (for $\tau_{\Omega_b^-}$ only). A measurement is also made of the mass difference, $m_{\Omega_b^-}-m_{\Xi_b^-}$, and the corresponding $\Omega_b^-$ mass, which yields \begin{align*} m_{\Omega_b^-}-m_{\Xi_b^-} &= 247.4\pm3.2\pm0.5~{\rm MeV}/c^2, \\ m_{\Omega_b^-} &= 6045.1\pm3.2\pm 0.5\pm0.6~{\rm MeV}/c^2. \end{align*} These results are consistent with previous measurements.Comment: 11 pages, 5 figures, All figures and tables, along with any supplementary material and additional information, are available at https://lhcbproject.web.cern.ch/lhcbproject/Publications/LHCbProjectPublic/LHCb-PAPER-2016-008.htm