3,286 research outputs found
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 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 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 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
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 mixing and rare decays through the quark
level 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 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/ tracks using the misaligned geometry compared to the re-aligned case as well as the default. It is shown that after alignment the J mass resolution is degraded by at most 3~\%
Measurement of the relative rate of prompt χc0, χc1 and χc2 production at √s=7TeV
Prompt production of charmonium χc0, χc1 and χc2 mesons is studied using proton-proton collisions at the LHC at a centre-of-mass energy of √s=7TeV. The χc mesons are identified through their decay to J/ψγ, with J/ψ→μ+mu− using photons that converted in the detector. A data sample, corresponding to an integrated luminosity of 1.0fb−1 collected by the LHCb detector, is used to measure the relative prompt production rate of χc1 and χc2 in the rapidity range 2.0<y<4.5 as a function of the J/ψ transverse momentum from 3 to 20 GeV/c. First evidence for χc0 meson production at a hadron collider is also presented
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
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