The production of J/ψ 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/ψ in the rapidity range 2<yJ/ψ<4.5 and transverse momentum pTJ/ψ<10 GeV/c isσJ/ψJ/ψ=5.1±1.0±1.1 nb, where the first uncertainty is statistical and the second systematic.
An analysis of B±→DK± and B±→Dπ± decays is presented where the D meson is reconstructed in the two-body final states: K±π∓, K+K− and π+π−. Using 1.0 fb−1 of s=7TeVpp collisions, measurements of ...several observables are made including the first observation of the suppressed mode B±→π±K∓DK±. CP violation in B±→DK± decays is observed with 5.8σ significance.
The prompt production of the charmonium χc1 and χc2 mesons has been studied in proton–proton collisions at the Large Hadron Collider at a centre-of-mass energy of s=7 TeV. The χc mesons are ...identified through their decays χc→J/ψγ with J/ψ→μ+μ− using 36 pb−1 of data collected by the LHCb detector in 2010. The ratio of the prompt production cross-sections for the two χc spin states, σ(χc2)/σ(χc1), has been determined as a function of the J/ψ transverse momentum, pTJ/ψ, in the range from 2 to 15 GeV/c. The results are in agreement with the next-to-leading order non-relativistic QCD model at high pTJ/ψ and lie consistently above the pure leading-order colour-singlet prediction.
A
bstract
A search for previously unobserved decays of beauty baryons to the final states
and
is reported. The analysis is based on a data sample corresponding to an integrated luminosity of 1
.
0 fb
...−1
of
pp
collisions. The
decay is observed with a significance of 8
.
6
σ
, with branching fraction
where the uncertainties are statistical, systematic, from the ratio of fragmentation fractions
and from the branching fraction of the
B
0
→
K
0
π
+
π
−
normalisation channel, respectively. A first measurement is made of the
CP
asymmetry, giving
No significant signals are seen for
decays,
decays to both the
and
final states, and the
decay, and upper limits on their branching fractions are reported.
The cross-section for inclusive ϕ meson production in pp collisions at a centre-of-mass energy of 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 ϕ 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 ϕ production in this kinematic range is σ(pp→ϕX)=1758±19(stat)−14+43(syst)±182(scale) μb, where the first 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.
Using 1.0 fb−1 of pp collision data collected at a centre-of-mass energy of s=7 TeV with the LHCb detector, measurements of the polarization amplitudes, strong phase difference and triple product ...asymmetries in the Bs0→ϕϕ decay mode are presented. The measured values are|A0|2=0.365±0.022(stat)±0.012(syst),|A⊥|2=0.291±0.024(stat)±0.010(syst),cos(δ∥)=−0.844±0.068(stat)±0.029(syst),AU=−0.055±0.036(stat)±0.018(syst),AV=0.010±0.036(stat)±0.018(syst).
A measurement of the effective Bs0→K+K− lifetime is presented using approximately 37 pb−1 of data collected by LHCb during 2010. This quantity can be used to put constraints on contributions from ...processes beyond the Standard Model in the Bs0 meson system and is determined by two complementary approaches asτKK=1.440±0.096 (stat)±0.008 (syst)±0.003 (model) ps.
Evidence for the decay X(3872)→ψ(2S)γ Ajaltouni, Z.; An, L.; Andreotti, M. ...
Nuclear physics. B,
09/2014, Letnik:
886, Številka:
C
Journal Article
Recenzirano
Odprti dostop
Evidence for the decay mode X(3872)→ψ(2S)γ in B+→X(3872)K+ decays is found with a significance of 4.4 standard deviations. The analysis is based on a data sample of proton–proton collisions, ...corresponding to an integrated luminosity of 3 fb−1, collected with the LHCb detector, at centre-of-mass energies of 7 and 8 TeV. The ratio of the branching fraction of the X(3872)→ψ(2S)γ decay to that of the X(3872)→J/ψγ decay is measured to beB(X(3872)→ψ(2S)γ)B(X(3872)→J/ψγ)=2.46±0.64±0.29, where the first uncertainty is statistical and the second is systematic. The measured value does not support a pure DD¯⁎ molecular interpretation of the X(3872) state.
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