A search for Formula omitted violation in charmless four-body decays of Formula omitted and Formula omitted baryons with a proton and three charged mesons in the final state is performed. To cancel ...out production and detection charge-asymmetry effects, the search is carried out by measuring the difference between the Formula omitted asymmetries in a charmless decay and in a decay with an intermediate charmed baryon with the same particles in the final state. The data sample used was recorded in 2011 and 2012 with the LHCb detector and corresponds to an integrated luminosity of Formula omitted. A total of 18 Formula omitted asymmetries are considered, either accounting for the full phase space of the decays or exploring specific regions of the decay kinematics. No significant Formula omitted-violation effect is observed in any of the measurements.
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Search for the rare decay [Formula omitted] Aaij, R; Beteta, C. Abellán; Adeva, B ...
The European physical journal. C, Particles and fields,
08/2019, Volume:
79, Issue:
8
Journal Article
Peer reviewed
Open access
A search for the rare leptonic decay Formula omitted is performed using proton-proton collision data corresponding to an integrated luminosity of Formula omitted collected by the LHCb experiment. The ...search is carried out in the region where the lowest of the two Formula omitted mass combinations is below Formula omitted. The data are consistent with the background-only hypothesis and an upper limit of Formula omitted at 95% confidence level is set on the branching fraction in the stated kinematic region.
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Two new algorithms for use in the analysis of pp collision are developed to identify the flavour of B0 mesons at production using pions and protons from the hadronization process. The algorithms are ...optimized and calibrated on data, using B0→D-π+ decays from pp collision data collected by LHCb at centre-of-mass energies of 7 and 8 TeV . The tagging power of the new pion algorithm is 60% greater than the previously available one; the algorithm using protons to identify the flavour of a B0 meson is the first of its kind.
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The branching fraction and direct Formula omitted asymmetry of the decay Formula omitted are measured using proton-proton collision data collected with the LHCb detector at centre-of-mass energies of ...7 and 8 TeV, corresponding to a total integrated luminosity of 3 Formula omitted. The following results are obtained: B(B+right arrowJ/psirho+)=(3.81-0.24+0.25±0.35)x10-5,ACP(B+right arrowJ/psirho+)=-0.045-0.057+0.056±0.008,where the first uncertainties are statistical and the second systematic. Both measurements are the most precise to date.
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A Dalitz plot analysis of Formula omitted decays is performed using data samples of pp collisions collected with the Formula omitted detector at centre-of-mass energies of Formula omitted and Formula ...omitted, corresponding to a total integrated luminosity of Formula omitted. A satisfactory description of the data is obtained when including a contribution representing an exotic Formula omitted resonant state. The significance of this exotic resonance is more than three standard deviations, while its mass and width are Formula omitted and Formula omitted, respectively. The spin-parity assignments Formula omitted and Formula omitted are both consistent with the data. In addition, the first measurement of the Formula omitted branching fraction is performed and gives B(B0right arrowetac(1S)K+pi-)=(5.73±0.24±0.13±0.66)x10-4,where the first uncertainty is statistical, the second systematic, and the third is due to limited knowledge of external branching fractions.
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A search for the decay
is performed, based on a data sample of proton-proton collisions corresponding to an integrated luminosity of
, collected by the LHCb experiment at centre-of-mass energies of ...7 and 8
. The observed yield is consistent with the background-only hypothesis, yielding a limit on the branching fraction of
at
confidence level. This result improves the previous upper limit on the branching fraction by an order of magnitude.
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Using decays to
-meson pairs, the inclusive production of charmonium states in
-hadron decays is studied with
collision data corresponding to an integrated luminosity of
, collected by the LHCb ...experiment at centre-of-mass energies of 7 and 8 TeV. Denoting by
the inclusive branching fraction of a
hadron to a charmonium state
that decays into a pair of
mesons, ratios
are determined as
,
,
,
,
and
. Here and below the first uncertainties are statistical and the second systematic. Upper limits at 90% confidence level for the inclusive production of
(3872),
(3915) and
states are obtained as
,
and
. Differential cross-sections as a function of transverse momentum are measured for the
and
states. The branching fraction of the decay
is measured for the first time,
. Here the third uncertainty is due to the branching fraction of the decay
, which is used for normalization. No evidence for intermediate resonances is seen. A preferentially transverse
polarization is observed. The measurements allow the determination of the ratio of the branching fractions for the
decays to
and
as
.
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The first observation of the semileptonic b-baryon decay Λ_{b}^{0}→Λ_{c}^{+}τ^{-}νover ¯_{τ}, with a significance of 6.1σ, is reported using a data sample corresponding to 3 fb^{-1} of integrated ...luminosity, collected by the LHCb experiment at center-of-mass energies of 7 and 8 TeV at the LHC. The τ^{-} lepton is reconstructed in the hadronic decay to three charged pions. The ratio K=B(Λ_{b}^{0}→Λ_{c}^{+}τ^{-}νover ¯_{τ})/B(Λ_{b}^{0}→Λ_{c}^{+}π^{-}π^{+}π^{-}) is measured to be 2.46±0.27±0.40, where the first uncertainty is statistical and the second systematic. The branching fraction B(Λ_{b}^{0}→Λ_{c}^{+}τ^{-}νover ¯_{τ})=(1.50±0.16±0.25±0.23)% is obtained, where the third uncertainty is from the external branching fraction of the normalization channel Λ_{b}^{0}→Λ_{c}^{+}π^{-}π^{+}π^{-}. The ratio of semileptonic branching fractions R(Λ_{c}^{+})≡B(Λ_{b}^{0}→Λ_{c}^{+}τ^{-}νover ¯_{τ})/B(Λ_{b}^{0}→Λ_{c}^{+}μ^{-}νover ¯_{μ}) is derived to be 0.242±0.026±0.040±0.059, where the external branching fraction uncertainty from the channel Λ_{b}^{0}→Λ_{c}^{+}μ^{-}νover ¯_{μ} contributes to the last term. This result is in agreement with the standard model prediction.
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A measurement of the time-dependent CP-violating asymmetry in Bs0→ϕϕ\ {B}_s^0\to \phi \phi \ decays is presented. Using a sample of proton-proton collision data corresponding to an integrated ...luminosity of 5.0 fb−1 collected by the LHCb experiment at centre-of-mass energies s\ \sqrt{s} \ = 7 TeV in 2011, 8 TeV in 2012 and 13 TeV in 2015 and 2016, a signal yield of around 9000 Bs0→ϕϕ\ {B}_s^0\to \phi \phi \ decays is obtained. The CP-violating phase ϕsss¯s\ {\phi}_s^{s\overline{s}s} \ is measured to be −0.073 ± 0.115(stat) ± 0.027(syst) rad, under the assumption it is independent of the helicity of the ϕϕ decay. In addition, the CP-violating phases of the transverse polarisations under the assumption of CP conservation of the longitudinal phase are measured. The helicity-independent direct CP-violation parameter is also measured, and is found to be |λ| = 0.99 ± 0.05(stat) ± 0.01(syst). In addition, T-odd triple-product asymmetries are measured. The results obtained are consistent with the hypothesis of CP conservation in b¯→s¯ss¯s\ \overline{b}\to \overline{s}s\overline{s}s \ transitions. Finally, a limit on the branching fraction of the B0 → ϕϕ decay is determined to be BB0→ϕϕ<2.7×10−8\ \mathcal{B}\left({B}^0\to \phi \phi \right)<2.7\times {10}^{-8} \ at 90 % confidence level.
Using proton-proton collision data, collected with the LHCb detector and corresponding to 1.0, 2.0 and 1.9 fb−1 of integrated luminosity at the centre-of-mass energies of 7, 8, and 13 TeV, ...respectively, the decay Λb0→χc1\ {\Lambda}_{\mathrm{b}}^0\to {\upchi}_{\mathrm{c}1} \(3872)pK− with χc1(3872) → J/ψ π+π− is observed for the first time. The significance of the observed signal is in excess of seven standard deviations. It is found that (58 ± 15)% of the decays proceed via the two-body intermediate state χc1(3872)Λ(1520). The branching fraction with respect to that of the Λb0\ {\Lambda}_{\mathrm{b}}^0 \ → ψ(2S)pK− decay mode, where the ψ(2S) meson is reconstructed in the J/ψ π+π− final state, is measured to be:βΛb0→χc13872pK−βΛb0→ψ2SpK−×βχc13872→J/ψπ+π−βψ2S→J/ψπ+π−=5.4±1.1±0.2×10−2,\ \frac{\beta \left({\Lambda}_{\mathrm{b}}^0\to {\upchi}_{\mathrm{c}1}(3872){\mathrm{pK}}^{-}\right)}{\beta \left({\Lambda}_{\mathrm{b}}^0\to \uppsi \left(2\mathrm{S}\right){\mathrm{pK}}^{-}\right)}\times \frac{\beta \left({\upchi}_{\mathrm{c}1}(3872)\to \mathrm{J}/\uppsi {\uppi}^{+}{\uppi}^{-}\right)}{\beta \left(\uppsi \left(2\mathrm{S}\right)\to \mathrm{J}/\uppsi {\uppi}^{+}{\uppi}^{-}\right)}=\left(5.4\pm 1.1\pm 0.2\right)\times {10}^{-2}, \where the first uncertainty is statistical and the second is systematic.
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