Selection of LHCb results from Run I

At the eve of the second LHC data taking run, some of the most recent results obtained by the LHCb collaboration with Run I data are reviewed. Improved measurements on CP violation, unitary triangle and mixing parameters are shown. Recent progress on physics in the forward region is illustrated by examples picked up in the electroweak physics and beyond Standard Model searches.Comment: 7 pages, Contribution to the 10th Latin American Symposium on High Energy Physics (SILAFAE 2014

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

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

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

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

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

In-situ Spectroscopic Studies of Noble Metal Catalysts for CO Oxidation

本论文工作由四部分组成：1)纳米Au催化剂的制备及其低温CO氧化性能的研究，2)Pd上CO催化氧化的活性表面的研究，3)Ru/SiO2催化剂上CO催化氧化活性相的研究，4)Pt/SiO2/Mo(112)模型催化剂上庚烷脱氢环化构效关系的研究。 一、负载型Au催化剂的载体对Au的颗粒大小、形貌和荷电状态等有显著影响，进而改变Au催化剂相关的催化反应性能。很多文献报道表明Au易于在TiO2的氧缺陷位上成核，即Au原子或纳米簇在缺陷位上有较强的结合能。第一部分，我们将TiOx镀在SiO2载体上以期形成表面配位不饱和及具高缺陷位的载体，用于负载Au纳米粒子，并通过高温氢还原制得性能较好的负载Au催化...The dissertation is composed of the following four parts: 1) Preparation and characterization of Au catalysts for CO oxidation, 2) Identify the active surface for CO oxidation over Pd, 3) Identify the active site for CO oxidation over Ru/SiO2 catalysts, 4) Structure sensitivity of n-heptane dehydrocyclization on Pt/SiO2/Mo(112) model catalysts. Ⅰ. Supports are found to affect the size, electronic...学位：理学博士院系专业：化学化工学院化学系_物理化学(含化学物理)学号：2052008015019

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~\%

Observation of an Excited Bc+ State

Using pp collision data corresponding to an integrated luminosity of 8.5 fb-1 recorded by the LHCb experiment at center-of-mass energies of s=7, 8, and 13 TeV, the observation of an excited Bc+ state in the Bc+π+π- invariant-mass spectrum is reported. The observed peak has a mass of 6841.2±0.6(stat)±0.1(syst)±0.8(Bc+) MeV/c2, where the last uncertainty is due to the limited knowledge of the Bc+ mass. It is consistent with expectations of the Bc∗(2S31)+ state reconstructed without the low-energy photon from the Bc∗(1S31)+→Bc+γ decay following Bc∗(2S31)+→Bc∗(1S31)+π+π-. A second state is seen with a global (local) statistical significance of 2.2σ (3.2σ) and a mass of 6872.1±1.3(stat)±0.1(syst)±0.8(Bc+) MeV/c2, and is consistent with the Bc(2S10)+ state. These mass measurements are the most precise to date

Observation of two new Ξb−\Xi_b^- baryon resonances

Two structures are observed close to the kinematic threshold in the $\Xi_b^0 \pi^-$ mass spectrum in a sample of proton-proton collision data, corresponding to an integrated luminosity of 3.0 fb$^{-1}$ recorded by the LHCb experiment. In the quark model, two baryonic resonances with quark content $bds$ are expected in this mass region: the spin-parity $J^P = \frac{1}{2}^+$ and $J^P=\frac{3}{2}^+$ states, denoted $\Xi_b^{\prime -}$ and $\Xi_b^{*-}$. Interpreting the structures as these resonances, we measure the mass differences and the width of the heavier state to be $m(\Xi_b^{\prime -}) - m(\Xi_b^0) - m(\pi^{-}) = 3.653 \pm 0.018 \pm 0.006$ MeV$/c^2$, $m(\Xi_b^{*-}) - m(\Xi_b^0) - m(\pi^{-}) = 23.96 \pm 0.12 \pm 0.06$ MeV$/c^2$, $\Gamma(\Xi_b^{*-}) = 1.65 \pm 0.31 \pm 0.10$ MeV, where the first and second uncertainties are statistical and systematic, respectively. The width of the lighter state is consistent with zero, and we place an upper limit of $\Gamma(\Xi_b^{\prime -}) < 0.08$ MeV at 95% confidence level. Relative production rates of these states are also reported.Comment: 17 pages, 2 figure