2,014 research outputs found
Searches for Majorana Neutrinos and Direct Searches for Exotics at LHCb
These proceedings present the LHCb results on Majorana neutrino searches and
direct production of exotic particles using the data collected during Run I of
LHC. For the former, Majorana neutrinos are searched for both on-shell and
off-shell in and decays to final states with two same-sign muons. For
the latter, different types of new particles are studied profiting the unique
coverage of LHCb with respect to other detectors.Comment: 9 pages, 27 figures. To be published in the LISHEP 2015 proceeding
Muon Identification in the LHCb experiment
A short summary of the LHCb muon identification procedure is given in this
article. First, the muon system of LHCb is presented, together with some
examples of physics measurements of the experiment where the muon
identification is crucial. Then, the muon identification algorithm is
introduced in three single steps. With this, the efficiency vs.
misidentification rate is shown for MC simulated data. The way this method will
be calibrated with real data is also seen. Finally, some preliminary muon
identification results with proton-proton collisions at sqrt(s) = 900 GeV are
presented.Comment: Proceedings for the Moriond 2010 E
The Muon Identification Procedure of the LHCb Experiment for the First Data
We present a refined muon identification algorithm for the LHCb experiment suitable for the first period of data taking. The new algorithm is robust against possible inefficiencies of the Muon Detector and takes properly into account the momentum dependence, so it can be tuned with calibration samples and exported to signal samples with different momentum spectra without large corrections. The average performance depends on the momentum spectrum of the analyzed sample: with the current simulation we find for tracks with p > 3 GeV/c in a generic b-inclusive sample a muon identification efficiency of 90 % for a misidentification rate of hadrons and electrons of ~2.4 % (~ 1 % excluding pi's and K's decays in flight). Additional rejection power can be obtained by combining in a proper way the informations coming from all the other subdetectors in a global Likelihood: in this case for a muon identification efficiency of 90 % we find a misidentification rate of ~1.8 % (~ 0.8 % excluding pi's and K's decays in flight
Performance of the Muon Identification at LHCb
The performance of the muon identification in LHCb is extracted from data
using muons and hadrons produced in J/\psi->\mu\mu, \Lambda->p\pi and
D^{\star}->\pi D0(K\pi) decays. The muon identification procedure is based on
the pattern of hits in the muon chambers. A momentum dependent binary
requirement is used to reduce the probability of hadrons to be misidentified as
muons to the level of 1%, keeping the muon efficiency in the range of 95-98%.
As further refinement, a likelihood is built for the muon and non-muon
hypotheses. Adding a requirement on this likelihood that provides a total muon
efficiency at the level of 93%, the hadron misidentification rates are below
0.6%.Comment: 17 pages, 10 figure
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
Study of decays to the final state and evidence for the decay
A study of decays is performed for the first time
using data corresponding to an integrated luminosity of 3.0
collected by the LHCb experiment in collisions at centre-of-mass energies
of and TeV. Evidence for the decay
is reported with a significance of 4.0 standard deviations, resulting in the
measurement of
to
be .
Here denotes a branching fraction while and
are the production cross-sections for and mesons.
An indication of weak annihilation is found for the region
, 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
flavour tagging using charm decays at the LHCb experiment
An algorithm is described for tagging the flavour content at production of
neutral mesons in the LHCb experiment. The algorithm exploits the
correlation of the flavour of a meson with the charge of a reconstructed
secondary charm hadron from the decay of the other hadron produced in the
proton-proton collision. Charm hadron candidates are identified in a number of
fully or partially reconstructed Cabibbo-favoured decay modes. The algorithm is
calibrated on the self-tagged decay modes and using of data collected by the LHCb
experiment at centre-of-mass energies of and
. Its tagging power on these samples of
decays is .Comment: All figures and tables, along with any supplementary material and
additional information, are available at
http://lhcbproject.web.cern.ch/lhcbproject/Publications/LHCbProjectPublic/LHCb-PAPER-2015-027.htm
Measurement of the inelastic pp cross-section at a centre-of-mass energy of 13TeV
The cross-section for inelastic proton-proton collisions at a centre-of-mass energy of 13TeV is measured with the LHCb detector. The fiducial cross-section for inelastic interactions producing at least one prompt long-lived charged particle with momentum p > 2 GeV/c in the pseudorapidity range 2 < η < 5 is determined to be ϭ acc = 62:2 ± 0:2 ± 2:5mb. The first uncertainty is the intrinsic systematic uncertainty of the measurement, the second is due to the uncertainty on the integrated luminosity. The statistical uncertainty is negligible. Extrapolation to full phase space yields the total inelastic proton-proton cross-section ϭ inel = 75:4 ± 3:0 ± 4:5mb, where the first uncertainty is experimental and the second due to the extrapolation. An updated value of the inelastic cross-section at a centre-of-mass energy of 7TeV is also reported
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