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The relative abundance of the three decay modes B-0 -> D-K+, B-0 -> D-pi(+), and B-s(0) -> D-s(-)pi(+) produced in 7 TeV pp collisions at the LHC is determined from data corresponding to an integrated luminosity of 35 pb(-1). The branching fraction of B-0 -> D-K+ is found to be B(B-0 -> D-K+) = (2.01 +/- 0.18(stat) +/- 0.14(syst)) x 10(-4). The ratio of fragmentation fractions f(s)/f(d) is determined through the relative abundance of B-s(0) -> D-s(-)pi(+) to B-0 -> D-K+ and B-0 -> D-pi(+), leading to f(s)/f(d) = 0.253 +/- 0.017 +/- 0.017 +/- 0.020, where the uncertainties are statistical, systematic, and theoretical, respectively.
Branching fractions of the decays H-b -> H-c pi(-)pi(+)pi(-) relative to H-b -> H-c pi(-) are presented, where H-b (H-c) represents (B) over bar (0) (D+), B-(D-0), (B) over bar (0)(s) (D-s(+)), and Lambda(0)(b) (Lambda(+)(c)). The measurements are performed with the LHCb detector using 35 pb(-1) of data collected at root s = 7 TeV. The ratios of branching fractions are measured to be [B (B) over bar -> D+pi(-)pi(+)pi(-))]/[B((B) over bar (0)-> D+pi(-))] = 2.38 +/- 0.11 +/- 0.21, [B(B- -> D-0 pi(-)pi(+)pi(-))]/[B(B- -> D-0 pi(-))] = 1.27 +/- 0.06 +/- 0.11, [B((B) over bar (0)(s) -> D-s(+)pi(-)pi(+)pi(-))]/[B((B) over bar (0)(s) -> D-s(+)pi(-))] = 2.01 +/- 0.37 +/- 0.20, [B(Lambda(0)(b) ->Lambda(+)(c)pi(-) pi(+)pi(-))]/[B(Lambda(0)(b) ->Lambda(+)(c)pi(-))] = 1.43 +/- 0.16 +/- 0.13 We also report measurements of partial decay rates of the...
The cross-section for inclusive phi meson production in pp collisions at a centre-of-mass energy of root s = 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 phi transverse momentum p(T) and rapidity y in the region 0.6 < p(T) < 5.0 GeV/c and 2.44 < y < 4.06. The cross-section for inclusive phi production in this kinematic range is sigma (pp -> phi X) = 1758 +/- 19(stat)(-14)(+14)(syst) +/- 182(scale) mu b, where the first systematic uncertainty depends on the p(T) and y region and the second is related to the overall scale. Predictions based on the PYTHIA 6.4 generator underestimate the cross-section. (C) 2011 CERN. Published by Elsevier B.V. All rights reserved.
The (Lambda) over bar/Lambda and (Lambda) over bar /K-S(0) production ratios are measured by the LHCb detector from 0.3 nb(-1) of pp collisions delivered by the LHC at root s = 0.9TeV and 1.8 nb-1 at root s = 7TeV. Both ratios are presented as a function of transverse momentum, p(T), and rapidity, y, in the ranges 0.15 < p(T) < 2.50GeV/c and 2.0 < y < 4.5. Results at the two energies are in good agreement as a function of rapidity loss, Delta y = y(beam) - y, and are consistent with previous measurements. The ratio (Lambda) over bar/Lambda, measuring the transport of baryon number from the collision into the detector, is smaller in data than predicted in simulation, particularly at high rapidity. The ratio (Lambda) over bar /K-S(0), measuring the baryon-to-meson suppression in strange quark hadronisation, is significantly larger than e...
The production of J/psi mesons in proton-proton collisions at root s = 7 TeV is studied with the LHCb detector at the LHC. The differential cross-section for prompt J/psi production is measured as a function of the J/psi transverse momentum p(T) and rapidity y in the fiducial region p(T) is an element of [0; 14] GeV/c and y is an element of [2.0; 4.5]. The differential cross-section and fraction of J/psi from b-hadron decays are also measured in the same p(T) and y ranges. The analysis is based on a data sample corresponding to an integrated luminosity of 5.2 pb(-1). The measured cross-sections integrated over the fiducial region are 10.52 +/- 0.04 +/- 1.40(-2.20)(+1.64) mu b for prompt J/psi production and 1.14 +/- 0.01 +/- 0.16 mu b for J/psi from b-hadron decays, where the first uncertainty is statistical and the second systematic. ...
A search for the decays Bs0 -> mu(+)mu(-) and B0 -> mu(+)mu(-) is performed with about 37 pb(-1) of pp collisions at root s = 7 TeV collected by the LHCb experiment at the Large Hadron Collider at CERN. The observed numbers of events are consistent with the background expectations. The resulting upper limits on the branching ratios are B(B-s(0) -> mu(+)mu(-) ) <5.6 x 10(-8) and B(B0 -> mu(+)mu(-) ) <1.5 x 10(-8) at 95% confidence level. (C) 2011 CERN. Published by Elsevier B.V. All rights reserved.
Using data collected with the LHCb detector in proton-proton collisions at a centre-of-mass energy of 7 TeV, the semileptonic decays (B) over bar (0)(s) -> D+X mu(-)(nu) over bar and (B) over bar (0)(s) -> (DK+X)-K-0 mu(-)(nu) over bar are detected. Two structures are observed in the (DK+)-K-0 mass spectrum at masses consistent with the known D-s1(2536)(+) and D-s2*(2573)(+) mesons. The measured branching fractions relative to the total (B) over bar (0)(s) semileptonic rate are B((B) over bar (0)(s) -> (Ds2X)-X-*mu(-)(nu) over bar /B(B-2(-0) -> X mu(-)(nu) over bar) = (3.3 +/- 1.0 +/- 0.4)%, and B((B) over bar (0)(s) -> (Ds2X)-X-*mu(-)(nu) over bar /B(B-2(-0) -> X mu(-)(nu) over bar) = (5.4 +/- 1.2 +/- 0.5)%, where the first uncertainty is statistical and the second is systematic. This is the first observation of the D-s2*(+) state in ...
The production of J/psi pairs in proton-proton collisions at a centre-of-mass energy of 7 TeV has been observed using an integrated luminosity of 37.5 pb(-1) collected with the LHCb detector. The production cross-section for pairs with both J/psi in the rapidity range 2 < y(J/psi) < 4.5 and transverse momentum p(T)(J/psi) < 10 GeV/c is
Measurement of mixing-induced CP violation in (B) over bar (0)(s) decays is of prime importance in probing new physics. So far only the channel (B) over bar (0)(s) -> J/psi phi has been used. Here we report on a measurement using an LHCb data sample of 0.41 fb(-1), in the CP odd eigenstate J/psi f(0)(980), where f(0)(980) -> pi(+)pi(-). A time-dependent fit of the data with the (B) over bar (0)(s) lifetime and the difference in widths of the heavy and light eigenstates constrained to the values obtained from (B) over bar (0)(s) -> J/psi phi yields a value of the CP violating phase of -0.44 +/- 0.44 +/- 0.02 rad, consistent with the Standard Model expectation. (C) 2012 CERN. Published by Elsevier B.V. All rights reserved.
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