A
bstract
The production of
W
and
Z
bosons in association with jets is studied in the forward region of proton-proton collisions collected at a centre-of-mass energy of 8 TeV by the LHCb experiment, ...corresponding to an integrated luminosity of 1.98 ± 0.02 fb
−1
. The
W
boson is identified using its decay to a muon and a neutrino, while the
Z
boson is identified through its decay to a muon pair. Total cross-sections are measured and combined into charge ratios, asymmetries, and ratios of
W
+jet and
Z
+jet production cross-sections. Differential measurements are also performed as a function of both boson and jet kinematic variables. All results are in agreement with Standard Model predictions.
A search for the decays Bc+→J/ψD(*)0K+ and Bc+→J/ψD(*)+K*0 is performed with data collected at the LHCb experiment corresponding to an integrated luminosity of 3 fb−1. The decays Bc+→J/ψD0K+ and ...Bc+→J/ψD*0K+ are observed for the first time, while first evidence is reported for the Bc+→J/ψD*+K*0 and Bc+→J/ψD+K*0 decays. The branching fractions of these decays are determined relative to the Bc+→J/ψπ+ decay. The Bc+ mass is measured, using the J/ψD0K+ final state, to be 6274.28±1.40(stat)±0.32(syst) MeV/c2. This is the most precise single measurement of the Bc+ mass to date.
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The differential cross-section for the inclusive production of ψ(2S) mesons in pp collisions at s√=7 TeVs=7 TeV has been measured with the LHCb detector. The data sample corresponds to an integrated ...luminosity of 36 pb−1. The ψ(2S) mesons are reconstructed in the decay channels ψ(2S)→μ + μ − and ψ(2S)→J/ψπ + π −, with the J/ψ meson decaying into two muons. Results are presented both for promptly produced ψ(2S) mesons and for those originating from b-hadron decays. In the kinematic range p T(ψ(2S))≤16 GeV/c and 2<y(ψ(2S))≤4.5 we measure
https://static-content.springer.com/image/art%3A10.1140%2Fepjc%2Fs10052-012-2100-4/MediaObjects/10052_2012_2100_Equa_HTML.gif
where the last uncertainty on the prompt cross-section is due to the unknown ψ(2S) polarization. Recent QCD calculations are found to be in good agreement with our measurements. Combining the present result with the LHCb J/ψ measurements we determine the inclusive branching fraction
https://static-content.springer.com/image/art%3A10.1140%2Fepjc%2Fs10052-012-2100-4/MediaObjects/10052_2012_2100_Equb_HTML.gif
where the last uncertainty is due to the (b→J/ψX)B(b→J/ψX) , (J/ψ→μ+μ−)B(J/ψ→μ+μ−) and (ψ(2S)→e+e−)B(ψ(2S)→e+e−) branching fraction uncertainties.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
A
bstract
The production of Υ mesons in pp collisions at
s
=
7
and 8 TeV is studied with the LHCb detector using data samples corresponding to an integrated luminosity of 1 fb
−1
and 2 fb
−1
...respectively. The production cross-sections and ratios of cross-sections are measured as functions of the meson transverse momentum
p
and rapidity
y
, for
p <
30 GeV
/c
and 2
.
0
< y <
4
.
5.
The polarisation of prompt
ψ
(
2
S
)
mesons is measured by performing an angular analysis of
ψ
(
2
S
)
→
μ
+
μ
-
decays using proton-proton collision data, corresponding to an integrated luminosity ...of 1.0
fb
-
1
, collected by the LHCb detector at a centre-of-mass energy of 7 TeV. The polarisation is measured in bins of transverse momentum
p
T
and rapidity
y
in the kinematic region
3.5
<
p
T
<
15
GeV
/
c
and
2.0
<
y
<
4.5
, and is compared to theoretical models. No significant polarisation is observed.
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The first study is presented of CP violation with an amplitude analysis of the Dalitz plot of B0 → DK+π– decays, with D → K+π–, K+K–, and π+π–. The analysis is based on a data sample corresponding to ...3.0 fb–1 of pp collisions collected with the LHCb detector. No significant CP violation effect is seen, and constraints are placed on the angle γ of the unitarity triangle formed from elements of the Cabibbo-Kobayashi-Maskawa quark mixing matrix. Hadronic parameters associated with the B0 → DK*(892)0 decay are determined for the first time. These measurements can be used to improve the sensitivity to γ of existing and future studies of the B0 → DK*(892)0 decay.
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Using a pp collision data sample corresponding to an integrated luminosity of 3.0 fb–1, collected by the LHCb detector, we present the first search for the strangeness-changing weak decay Ξb– → ...Λ0bπ–. No b hadron decay of this type has been seen before. A signal for this decay, corresponding to a significance of 3.2 standard deviations, is reported.
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