9 research outputs found
First observation of the decay and a measurement of the ratio of branching fractions
The first observation of the decay using
data collected by the LHCb detector at a centre-of-mass energy of 7 TeV,
corresponding to an integrated luminosity of 36 pb, is reported. A
signal of events is obtained and the absence of signal is
rejected with a statistical significance of more than nine standard deviations.
The branching fraction is measured relative to
that of : , where the first uncertainty is statistical, the second systematic and
the third is due to the uncertainty on the ratio of the and
hadronisation fractions.Comment: 10 pages, 3 figures, submitted to Phys. Lett. B; ISSN 0370-269
Prompt K_short production in pp collisions at sqrt(s)=0.9 TeV
The production of K_short mesons in pp collisions at a centre-of-mass energy
of 0.9 TeV is studied with the LHCb detector at the Large Hadron Collider. The
luminosity of the analysed sample is determined using a novel technique,
involving measurements of the beam currents, sizes and positions, and is found
to be 6.8 +/- 1.0 microbarn^-1. The differential prompt K_short production
cross-section is measured as a function of the K_short transverse momentum and
rapidity in the region 0 < pT < 1.6 GeV/c and 2.5 < y < 4.0. The data are found
to be in reasonable agreement with previous measurements and generator
expectations.Comment: 6+18 pages, 6 figures, updated author lis
Observation of J/Ï-pair production in pp collisions at âs=7 TeV
The production of J/Ï pairs in protonâproton collisions at a centre-of-mass energy of 7 TeV has been observed using an integrated luminosity of 37.5 pbâ1 collected with the LHCb detector. The production cross-section for pairs with both J/Ï in the rapidity range 2 < yJ/Ï < 4.5 and transverse momentum pJ/Ï T <10 GeV/c is ÏJ/ÏJ/Ï =5.1±1.0±1.1 nb, where the ïŹrst uncertainty is statistical and the second systematic
Measurement of the inclusive Ï cross-section in pp collisions at âs=7 TeV
The cross-section for inclusive Ï meson production in pp collisions at a centre-of-mass energy of âs = 7 TeV has been measured with the LHCb detector at the Large Hadron Collider. The differential cross-section is measured as a function of the Ï transverse momentum pT and rapidity y in the region 0.6< pT <5.0 GeV/c and 2.44< y <4.06. The cross-section for inclusive Ï production in this kinematic range is Ï(ppâÏX)=1758±19(stat) +43â14(syst)±182(scale) ÎŒb, where the ïŹrst systematic uncertainty depends on the pT and y region and the second is related to the overall scale. Predictions based on the Pythia 6.4 generator underestimate the cross-section
First observation of Bs â J/Ïf0(980) decays
Using data collected with the LHCb detector in protonâproton collisions at a centre-of-mass energy of 7 TeV, the hadronic decay is observed. This CP eigenstate mode could be used to measure mixing-induced CP violation in the system. Using a fit to the Ï+Ïâ mass spectrum with interfering resonances gives . In the interval ±90 MeV around 980 MeV, corresponding to approximately two full f0 widths we also find , where in both cases the uncertainties are statistical and systematic, respectively
Measurement of sigma (pp -> bbX) at âs=7 TeV in the forward region
Decays of b hadrons into final states containing a D-0 meson and a muon are used to measure the bb; production cross-section in proton-proton collisions at a centre-of-mass energy of 7 TeV at the LHC. In the pseudorapidity interval 2 < eta < 6 and integrated over all transverse momenta we find that the average cross-section to produce b-flavoured or b-flavoured hadrons is (75.3 +/- 5.4 +/- 13.0) mu b
Road map for selected key measurements from LHCb
Six of the key physics measurements that will be made by the LHCb experiment, concerning CP asymmetries and rare B decays, are discussed in detail. The "road map" towards the precision measurements is presented, including the use of control channels and other techniques to understand the performance of the detector with the first data from the LHC.Six of the key physics measurements that will be made by the LHCb experiment, concerning CP asymmetries and rare B decays, are discussed in detail. The 'road map' towards the precision measurements is presented, including the use of control channels and other techniques to understand the performance of the detector with the first data from the LHC
Roadmap for Selected Key Measurements of LHCb
Six of the key physics measurements that will be made by the LHCb experiment, concerning CP asymmetries and rare B decays, are discussed in detail. The âroad mapâ towards the precision measurements is presented, including the use of control channels and other techniques to understand the performance of the detector with the first data from the LHC