Updated measurements of exclusive J/ψ and ψ(2S) production cross-sections in pp collisions at √s = 7 TeV

The differential cross-section as a function of rapidity has been measured for the exclusive production of J/psi and psi(2S) mesons in proton-proton collisions at root s = 7 TeV, using data collected by the LHCb experiment, corresponding to an integrated luminosity of 930 pb(-1). The cross-sections times branching fractions to two muons having pseudorapidities between 2.0 and 4.5 are measured to besigma (pp -> J/psi -> mu+mu-)(2.0 psi(2S)->mu+mu-)(2.0 < eta(mu +/-) < 4.5) = 6.5 +/- 0.9 +/- 0.4 pb,where the first uncertainty is statistical and the second is systematic. The measurements agree with next-to-leading order QCD predictions as well as with models that include saturation effects

Measurement of CP asymmetry in D-0 -&gt; K- K+ and D-0 -&gt; pi(-) pi(+) decays

Time-integrated CP asymmetries in D-0 decays to the final states K- K+ and pi(-) pi(+) are measured using proton-proton collisions corresponding to 3 fb(-1) of integrated luminosity collected at centre-of-mass energies of 7 TeV and 8 TeV. The D-0 mesons are produced in semileptonic b-hadron decays, where the charge of the accompanying muon is used to determine the initial flavour of the charm meson. The difference in CP asymmetries between the two final states is measured to beDelta A(CP) = A(CP)(K- K+) - A(CP)(pi(-) pi(+)) = (+0.14 +/- 0.16 (stat) +/- 0.08 (syst))% .A measurement of A(CP)(K- K+) is obtained assuming negligible CP violation in charm mixing and in Cabibbo-favoured D decays. It is found to beA(CP)(K- K+) = (-0.06 +/- 0.15 (stat) +/- 0.10 (syst))% ,where the correlation coefficient between Delta A(CP) and A(CP)(K- K+) is rho = 0.28. By combining these results, the CP asymmetry in the D-0 -&gt; pi(-) pi(+) channel is A(CP)(pi(-) pi(+)) = (-0.20 +/- 0.19 (stat) +/- 0.10 (syst))%

Observation of the decay B-s(0) -&gt; (D)over-bar(0)phi

First observation of the decay B-s(0) -> (D) over bar (0)phi is reported using pp collision data, corresponding to an integrated luminosity of 1.0 fb(-1), collected by the LHCb experiment at a centre-of-mass energy of 7 TeV. The significance of the signal is 6.5 standard deviations. The branching fraction is measured relative to that of the decay B-S(0) -> (D) over bar (0)phi to bebeta B-S(0) -> (D) over bar (0)phi/beta B-S(0) -> (D) over bar (0)(K) over bar*(0) = 0.069 +/- 0.013 (stat) +/- 0.007 (syst).The first measurement of the ratio of branching fractions for the decays beta B-S(0) -> (D) over bar (0)(K) over bar*(0) and beta B-S(0) -> (D) over bar (0)(K) over bar*(0) is found to bebeta B-S(0) -> (D) over bar (0)(K) over bar*(0/)beta B-S(0) -> (D) over bar (0)(K) over bar*(0=7.8) +/- 0.7(stat) +/- 0.3 (syst) +/- 0.6 (f(s)/f(d))where the last uncertainty is due to the ratio of the B(s)(0)and B-0 fragmentation fractions. (C) 2013 CERN. Published by Elsevier B.V. All rights reserved

First observation of the decay B-c(+) -&gt; J/psi K+

The decay B-c(+) -> J/psi K+ is observed for the first time using a data sample, corresponding to an integrated luminosity of 1.0 fb(-1), collected by the LHCb experiment in p p collisions at a centre-of-mass energy of 7 TeV. A yield of 46 +/- 12 events is reported, with a significance of 5.0 standard deviations. The ratio of the branching fraction of B-c(+) -> J/psi K+ to that of B-c(+) -> J/psi pi(+) is measured to be 0.069 +/- 0.019 +/- 0 : 005, where the first uncertainty is statistical and the second is systematic

Determination of the quark coupling strength vertical bar V-ub vertical bar using baryonic decays

In the Standard Model of particle physics, the strength of the couplings of the b quark to the u and c quarks, vertical bar V-ub vertical bar and vertical bar V-ub vertical bar, are governed by the coupling of the quarks to the Higgs boson. Using data from the LHCb experiment at the Large Hadron Collider, the probability for the Lambda(0)(b) baryon to decay into the p mu(-)(nu) over bar (mu) final state relative to the Lambda(+)(c)mu(-)(nu) over bar (mu) final state is measured. Combined with theoretical calculations of the strong interaction and a previously measured value of vertical bar V-ub vertical bar, the first vertical bar V-ub vertical bar measurement to use a baryonic decay is performed. This measurement is consistent with previous determinations of vertical bar V-ub vertical bar using B meson decays to specific final states and confirms the existing incompatibility with those using an inclusive sample of final states

Measurement of psi (2S) production cross-sections in proton-proton collisions at v s=7 and 13 TeV

The cross-sections of \u3c8(2 S) meson production in proton-proton collisions at s=13TeV are measured with a data sample collected by the LHCb detector corresponding to an integrated luminosity of 275pb-1. The production cross-sections for prompt \u3c8(2 S) mesons and those for \u3c8(2 S) mesons from b-hadron decays (\u3c8(2S)-from-b) are determined as functions of the transverse momentum, pT, and the rapidity, y, of the \u3c8(2 S) meson in the kinematic range 2&lt;20GeV/c and 2.0 &lt; y&lt; 4.5. The production cross-sections integrated over this kinematic region are \u3c3(prompt\u3c8(2S),13TeV)=1.430\ub10.005(stat)\ub10.099(syst)\u3bcb,\u3c3(\u3c8(2S)-from-b,13TeV)=0.426\ub10.002(stat)\ub10.030(syst)\u3bcb.A new measurement of \u3c8(2 S) production cross-sections in pp collisions at s=7TeV is also performed using data collected in 2011, corresponding to an integrated luminosity of 614pb-1. The integrated production cross-sections in the kinematic range 3.5&lt;14GeV/c and 2.0 &lt; y&lt; 4.5 are \u3c3(prompt\u3c8(2S),7TeV)=0.471\ub10.001(stat)\ub10.025(syst)\u3bcb,\u3c3(\u3c8(2S)-from-b,7TeV)=0.126\ub10.001(stat)\ub10.008(syst)\u3bcb.All results show reasonable agreement with theoretical calculations