A
bstract
The relative production rate of
$ B_s^0 $
and
B
0
mesons is determined with the hadronic decays
$ B_s^0\to D_s^{-}{\pi^{+}} $
and
B
0
→
D
−
K
+
. The measurement uses data corresponding to ...1.0 fb
−1
of
pp
collisions at a centre-of-mass energy of
$ \sqrt{s}=7 $
TeV recorded in the forward region with the LHCb experiment. The ratio of production rates,
f
s
/f
d
, is measured to be 0
.
238 ± 0
.
004 ± 0
.
015 ± 0
.
021, where the first uncertainty is statistical, the second systematic, and the third theoretical. This is combined with a previous LHCb measurement to obtain
f
s
/f
d
= 0
.
256 ± 0
.
020. The dependence of
f
s
/f
d
on the transverse momentum and pseudorapidity of the
B
meson is determined using the decays
$ B_s^0\to D_s^{-}{\pi^{+}} $
and
B
0
→
D
−
π
+
. There is evidence for a decrease with increasing transverse momentum, whereas the ratio remains constant as a function of pseudorapidity. In addition, the ratio of branching fractions of the decays
B
0
→
D
−
K
+
and
B
0
→
D
−
π
+
is measured to be 0
.
0822 ± 0
.
0011 (stat) ± 0
.
0025 (syst).
In the Standard Model of particle physics, the strength of the couplings of the b quark to the u and c quarks, |Vub| and |Vcb|, 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 Λb0 baryon to decay into the p final state relative to the final state is measured. Combined with theoretical calculations of the strong interaction and a previously measured value of |Vcb|, the first |Vub| measurement to use a baryonic decay is performed. This measurement is consistent with previous determinations of |Vub| using B meson decays to specific final states and confirms the existing incompatibility with those using an inclusive sample of final states.
Observation of the decay → J/ψ K+K−π Adinolfi, M.; Albrecht, J.; Anderlini, L. ...
The journal of high energy physics,
12/11, Letnik:
2013, Številka:
11
Journal Article
Recenzirano
Odprti dostop
A
bstract
The decay
→
J/ψK
+
K
−
π
+
is observed for the first time, using protonproton collisions collected with the LHCb detector corresponding to an integrated luminosity of 3 fb
−1
. A signal ...yield of 78 ± 14 decays is reported with a significance of 6.2 standard deviations. The ratio of the branching fraction of
→
J/ψK
+
K
−
π
+
decays to that of
→
J/ψπ
+
decays is measured to be 0
.
53 ± 0
.
10 ± 0
.
05, where the first uncertainty is statistical and the second is systematic.
The CP-violating charge asymmetry in B±→ϕK± decays is measured in a sample of pp collisions at 7 TeV centre-of-mass energy, corresponding to an integrated luminosity of 1.0 fb−1 collected by the LHCb ...experiment. The result is ACP(B±→ϕK±)=0.022±0.021±0.009, where the first uncertainty is statistical and the second systematic. In addition, a search for the B±→ϕπ± decay mode is performed, using the B±→ϕK± decay rate for normalization. An upper limit on the branching fraction B(B±→ϕπ±)<1.5×10−7 is set at 90% confidence level.
The production of J/ψ mesons in proton–proton collisions at √s = 7 TeV is studied with the LHCb detector at the LHC. The differential cross-section for prompt J/ψ production is measured as a function ...of the J/ψ transverse
momentum pT and rapidity y in the fiducial region pT ∈ 0; 14 GeV/c and y ∈ 2.0; 4.5. The differential cross-section and fraction of J/ψ from b-hadron decays are also measured in the same pT 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+1.64 −2.20 µb for prompt J/ψ production and 1.14 ± 0.01 ± 0.16 µb for J/ψ from b-hadron decays, where the first uncertainty is statistical and the second systematic. The prompt J/ψ production cross-section is obtained assuming no J/ψ polarisation and the third error indicates the acceptance uncertainty due to this assumption.
The angular distribution and differential branching fraction of the decay $B^{0} \to K^{*0} \mu^{+}\mu^{-}$ are studied using a data sample, collected by the LHCb experiment in $pp$ collisions at ...$\sqrt{s}=7\,{\rm TeV}$, corresponding to an integrated luminosity of $1.0\,{\rm fb}^{-1}$. 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 $q_{0}^{2} = 4.9 \pm 0.9 \,{\rm GeV}^{2}/c^{4}$, where the uncertainty is the sum of statistical and systematic uncertainties. The results are consistent with the Standard Model predictions.
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