1,202 research outputs found
Measurement of the kinematic variables of beauty particles produced in 350 GeV/c -Cu interactions
Using a sample of b\=b events, produced in interactions in a copper target, which includes events where the decays of both and are well reconstructed, we measure the differential distributions with respect to and as well as some two-particle kinematic variables. We also compare our results with a previous experiment and with predictions based on perturbative QCD
Azimuthal correlation between beauty particles produced in 350 GeV/c -Cu interactions
Using a sample of triggered events, produced in interactions in a copper target, we have identified b\=b events. These include events where the decays of both and are well reconstructed. We measure the azimuthal \hbox{correlation} between beauty particles, and compare our result with predictions based on perturbative QCD
LHCb Upgraded RICH 1 Engineering Design Review Report
During the Long Shutdown 2 of the LHC, the LHCb collaboration will replace the upstream
Ring Imaging Cherenkov detector (RICH 1). The magnetic shield of the current RICH 1
will be modified, new spherical and plane mirrors will be installed and a new gas enclosure
will be manufactured. New photon detectors (multianode photomultiplier tubes) will be
used and these, together with their readout electronics, require a new mechanical support
system. This document describes the new optical arrangement of RICH 1, its engineering
design, installation and alignment. A summary of the project schedule and institute
responsibilities is provided
LHCb Upgraded RICH 1 Engineering Design Review Report
During the Long Shutdown 2 of the LHC, the LHCb collaboration will replace the upstream
Ring Imaging Cherenkov detector (RICH 1). The magnetic shield of the current RICH 1
will be modified, new spherical and plane mirrors will be installed and a new gas enclosure
will be manufactured. New photon detectors (multianode photomultiplier tubes) will be
used and these, together with their readout electronics, require a new mechanical support
system. This document describes the new optical arrangement of RICH 1, its engineering
design, installation and alignment. A summary of the project schedule and institute
responsibilities is provided
Measurements of charmed-meson production in interactions between 350 GeV/c particles and nuclei
Charmed-meson production by ~GeV/ {} particles incident on copper and tungsten targets has been studied in the WA experiment, performed at the CERN spectrometer. Results obtained are reported and discussed. Reconstruction of decays from the set , , , and charge conjugates has yielded a sample of charmed mesons, produced with \xf > 0, \langle \xf \rangle = 0.18 and \langle {\pt}^2 \rangle = 1.86~{\rm (GeV/}c{\rm )}^2. Assuming a relationship between the cross-section, , per nucleus of mass and the nucleonic cross-section, , the value found for the detected charmed particles is . Taking , the measured cross-sections per nucleon for \xf > 0 production are ~barn for /, ~barn for / and ~barn for /. Differential cross-sections with respect to \xf and {\pt}^2 have been determined for the various types of charmed meson, and particle-antiparticle asymmetries have been analysed
Observation of two new baryon resonances
Two structures are observed close to the kinematic threshold in the mass spectrum in a sample of proton-proton collision data, corresponding
to an integrated luminosity of 3.0 fb recorded by the LHCb experiment.
In the quark model, two baryonic resonances with quark content are
expected in this mass region: the spin-parity and
states, denoted and .
Interpreting the structures as these resonances, we measure the mass
differences and the width of the heavier state to be
MeV,
MeV,
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
MeV at 95% confidence level. Relative
production rates of these states are also reported.Comment: 17 pages, 2 figure
Differential branching fraction and angular analysis of the decay B0âKâ0ÎŒ+ÎŒâ
The angular distribution and differential branching fraction of the decay B 0â K â0 ÎŒ + ÎŒ â are studied using a data sample, collected by the LHCb experiment in pp collisions at sâ=7 TeV, corresponding to an integrated luminosity of 1.0 fbâ1. Several angular observables are measured in bins of the dimuon invariant mass squared, q 2. A first measurement of the zero-crossing point of the forward-backward asymmetry of the dimuon system is also presented. The zero-crossing point is measured to be q20=4.9±0.9GeV2/c4 , where the uncertainty is the sum of statistical and systematic uncertainties. The results are consistent with the Standard Model predictions
Observation of associated production of a boson with a meson in the~forward region
A search for associated production of a boson with an open charm meson is
presented using a data sample, corresponding to an integrated luminosity of
of proton--proton collisions at a centre-of-mass energy
of 7\,TeV, collected by the LHCb experiment. %% Seven candidate events for
associated production of a boson with a meson and four candidate
events for a boson with a meson are observed with a combined
significance of 5.1standard deviations. The production cross-sections in the
forward region are measured to be where the first uncertainty is statistical and the
second systematic.Comment: 18 pages, 2 figure
Opposite-side flavour tagging of B mesons at the LHCb experiment
The calibration and performance of the oppositeside
flavour tagging algorithms used for the measurements
of time-dependent asymmetries at the LHCb experiment
are described. The algorithms have been developed using
simulated events and optimized and calibrated with
B
+ âJ/ÏK
+, B0 âJ/ÏK
â0 and B0 âD
ââ
Ό
+
ΜΌ decay
modes with 0.37 fbâ1 of data collected in pp collisions
at
â
s = 7 TeV during the 2011 physics run. The oppositeside
tagging power is determined in the B
+ â J/ÏK
+
channel to be (2.10 ± 0.08 ± 0.24) %, where the first uncertainty
is statistical and the second is systematic
Measurement of the lifetime
Using a data set corresponding to an integrated luminosity of ,
collected by the LHCb experiment in collisions at centre-of-mass energies
of 7 and 8 TeV, the effective lifetime in the
decay mode, , is measured to be ps. Assuming
conservation, corresponds to the lifetime of the light
mass eigenstate. This is the first measurement of the effective
lifetime in this decay mode.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-2016-017.htm
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