Abstract A search for the rare leptonic decay $${{{B} ^+}} \!\rightarrow {\mu ^+} {\mu ^-} {\mu ^+} {{\upnu } _\mu } $$ B+→μ+μ-μ+νμ is performed using proton-proton collision data corresponding to an ...integrated luminosity of $$4.7 \, {\hbox {fb}}^{-1}$$ 4.7fb-1 collected by the LHCb experiment. The search is carried out in the region where the lowest of the two $${\mu ^+\mu ^-} $$ μ+μ- mass combinations is below $$980 {\mathrm {\,MeV\!/}c^2} $$ 980MeV/c2 . The data are consistent with the background-only hypothesis and an upper limit of $$1.6 \times 10^{-8}$$ 1.6×10-8 at 95% confidence level is set on the branching fraction in the stated kinematic region.
Abstract The decay-time-dependent $$CP$$ CP asymmetry in $${{B} ^0_{s}} \rightarrow J/\psi {{K} ^+} {{K} ^-} $$ Bs0→J/ψK+K- decays is measured using proton–proton collision data, corresponding to an ...integrated luminosity of $$1.9\,\mathrm{fb}^{-1} $$ 1.9fb-1 , collected with the LHCb detector at a centre-of-mass energy of $$13\,\mathrm {TeV}$$ 13TeV in 2015 and 2016. Using a sample of approximately 117 000 signal decays with an invariant $${{K} ^+} {{K} ^-} $$ K+K- mass in the vicinity of the $$\phi (1020)$$ ϕ(1020) resonance, the $$CP$$ CP -violating phase $$\phi _s$$ ϕs is measured, along with the difference in decay widths of the light and heavy mass eigenstates of the $${{B} ^0_{s}} $$ Bs0 -$${{\overline{B}{}} {}^0_{s}} $$ B¯s0 system, $$\Delta \Gamma _s$$ ΔΓs . The difference of the average $${{B} ^0_{s}} $$ Bs0 and $${{B} ^0} $$ B0 meson decay widths, $$\Gamma _s-\Gamma _d$$ Γs-Γd , is determined using in addition a sample of $${{B} ^0} \rightarrow J/\psi {{K} ^+} {{\pi } ^-} $$ B0→J/ψK+π- decays. The values obtained are $$\phi _s = -0.083\pm 0.041\pm 0.006\mathrm { \,rad} $$ ϕs=-0.083±0.041±0.006rad , $$\Delta \Gamma _s = 0.077 \pm 0.008 \pm 0.003 {\mathrm { \,ps^{-1}}} $$ ΔΓs=0.077±0.008±0.003ps-1 and $$\Gamma _s-\Gamma _d = -0.0041 \pm 0.0024 \pm 0.0015{\mathrm { \,ps^{-1}}} $$ Γs-Γd=-0.0041±0.0024±0.0015ps-1 , where the first uncertainty is statistical and the second systematic. These are the most precise single measurements of these quantities to date and are consistent with expectations based on the Standard Model and with a previous LHCb analysis of this decay using data recorded at centre-of-mass energies 7 and 8 TeV. Finally, the results are combined with recent results from $${{B} ^0_{s}} \rightarrow J/\psi {{\pi } ^+} {{\pi } ^-} $$ Bs0→J/ψπ+π- decays obtained using the same dataset as this analysis, and with previous independent LHCb results.
Abstract The branching fraction and direct $$C\!P$$ CP asymmetry of the decay $${{{B} ^+}} \!\rightarrow {{J /\psi }} {{\rho } ^+} $$ B+→J/ψρ+ 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$$\,\text{ fb }^{-1}$$ fb-1 . The following results are obtained: $$\begin{aligned} \mathcal {B}({{B} ^+} \!\rightarrow {{J /\psi }} {{\rho } ^+} )&= (3.81^{+0.25}_{-0.24} \pm 0.35) \times 10^{-5},\\ \mathcal {A}^{{C\!P}} ({{B} ^+} \!\rightarrow {{J /\psi }} {{\rho } ^+} )&= -0.045^{+0.056}_{-0.057} \pm 0.008, \end{aligned}$$ B(B+→J/ψρ+)=(3.81-0.24+0.25±0.35)×10-5,ACP(B+→J/ψρ+)=-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.
Abstract The resonant structure of the radiative decay Λ b 0 → pK − γ $$ {\Lambda}_b^0\to {pK}^{-}\gamma $$ in the region of proton-kaon invariant-mass up to 2.5 GeV/c 2 is studied using ...proton-proton collision data recorded at centre-of-mass energies of 7, 8, and 13 TeV collected with the LHCb detector, corresponding to a total integrated luminosity of 9 fb −1. Results are given in terms of fit and interference fractions between the different components contributing to this final state. Only Λ resonances decaying to pK − are found to be relevant, where the largest contributions stem from the Λ(1520), Λ(1600), Λ(1800), and Λ(1890) states.
Abstract A Dalitz plot analysis of $${{B} ^0} \!\rightarrow \eta _c(1S) {{K} ^+} {{\pi } ^-} $$ B0→ηc(1S)K+π- decays is performed using data samples of pp collisions collected with the $$\text{ LHCb ...} $$ LHCb detector at centre-of-mass energies of $${\sqrt{s}} =7,~8$$ s=7,8 and $$13{\,\mathrm {Te}\mathrm {V}} $$ 13TeV , corresponding to a total integrated luminosity of $$4.7 \,\text{ fb }^{-1} $$ 4.7fb-1 . A satisfactory description of the data is obtained when including a contribution representing an exotic $$\eta _c(1S) \pi ^-$$ ηc(1S)π- resonant state. The significance of this exotic resonance is more than three standard deviations, while its mass and width are $$4096 \pm 20~^{+18}_{-22} \,\mathrm {Me}\mathrm {V} $$ 4096±20-22+18MeV and $$152 \pm 58~^{+60}_{-35} \,\mathrm {Me}\mathrm {V} $$ 152±58-35+60MeV , respectively. The spin-parity assignments $$J^P=0^+$$ JP=0+ and $$J^{P}=1^-$$ JP=1- are both consistent with the data. In addition, the first measurement of the $${{B} ^0} \!\rightarrow \eta _c(1S) {{K} ^+} {{\pi } ^-} $$ B0→ηc(1S)K+π- branching fraction is performed and gives $$\begin{aligned} \displaystyle \mathcal {B}({{B} ^0} \!\rightarrow \eta _c(1S) {{K} ^+} {{\pi } ^-} ) = (5.73 \pm 0.24 \pm 0.13 \pm 0.66) \times 10^{-4}, \end{aligned}$$ B(B0→ηc(1S)K+π-)=(5.73±0.24±0.13±0.66)×10-4, where the first uncertainty is statistical, the second systematic, and the third is due to limited knowledge of external branching fractions.
Abstract The ratio of production cross-sections of ψ(2S) over J/ψ mesons as a function of charged-particle multiplicity in proton-proton collisions at a centre-of-mass energy s $$ \sqrt{s} $$ = 13 ...TeV is measured with a data sample collected by the LHCb detector, corresponding to an integrated luminosity of 658 pb −1. The ratio is measured for both prompt and non-prompt ψ(2S) and J/ψ mesons. When there is an overlap between the rapidity ranges over which multiplicity and charmonia production are measured, a multiplicity-dependent modification of the ratio is observed for prompt mesons. No significant multiplicity dependence is found when the ranges do not overlap. For non-prompt production, the ψ(2S)-to-J/ψ production ratio is roughly independent of multiplicity, irrespective of the rapidity range over which the multiplicity is measured. The results are compared to predictions of the co-mover model and agree well except in the low multiplicity region. The ratio of production cross-sections of ψ(2S) over J/ψ mesons are cross-checked with other measurements in di-lepton channels and found to be compatible.
Abstract The cross-section of associated J/ψ-ψ(2S) production in proton-proton collisions at a centre-of-mass energy of s $$ \sqrt{s} $$ = 13 TeV is measured using a data sample corresponding to an ...integrated luminosity of 4.2 fb −1, collected by the LHCb experiment. The measurement is performed for both J/ψ and ψ(2S) mesons having transverse momentum p T < 14 GeV/c and rapidity 2.0 < y < 4.5, assuming negligible polarisation of the J/ψ and ψ(2S) mesons. The production cross-section is measured to be 4.5 ± 0.7 ± 0.3 nb, where the first uncertainty is statistical and the second systematic. The differential cross-sections are measured as functions of several kinematic variables of the J/ψ-ψ(2S) candidates. The results are combined with a measurement of J/ψ-J/ψ production, giving a cross-section ratio between J/ψ-ψ(2S) and J/ψ-J/ψ production of 0.274 ± 0.044 ± 0.008, where the first uncertainty is statistical and the second systematic.
Abstract A measurement of CP-violating observables associated with the interference of B 0 → D 0 K ⋆(892)0 and B 0 → D ¯ 0 K ⋆ 892 0 $$ {B}^0\to {\overline{D}}^0{K}^{\star }{(892)}^0 $$ decay ...amplitudes is performed in the D 0 → K ∓ π ± (π + π − ), D 0 → π + π − (π + π − ), and D 0 → K + K − final states using data collected by the LHCb experiment corresponding to an integrated luminosity of 9 fb −1. CP-violating observables related to the interference of B s 0 → D 0 K ¯ ⋆ 892 0 $$ {B}_s^0\to {D}^0{\overline{K}}^{\star }{(892)}^0 $$ and B s 0 → D ¯ 0 K ¯ ⋆ 892 0 $$ {B}_s^0\to {\overline{D}}^0{\overline{K}}^{\star }{(892)}^0 $$ are also measured, but no evidence for interference is found. The B 0 observables are used to constrain the parameter space of the CKM angle γ and the hadronic parameters r B 0 DK ⋆ $$ {r}_{B^0}^{DK\star } $$ and δ B 0 DK ⋆ $$ {\delta}_{B^0}^{DK\star } $$ with inputs from other measurements. In a combined analysis, these measurements allow for four solutions in the parameter space, only one of which is consistent with the world average.
Abstract Measurements of the branching fraction ratio B ϕ → μ + μ − / B ϕ → e + e − $$ \mathcal{B}\left(\phi \to {\mu}^{+}{\mu}^{-}\right)/\mathcal{B}\left(\phi \to {e}^{+}{e}^{-}\right) $$ with D s ...+ → π + ϕ $$ {D}_s^{+}\to {\pi}^{+}\phi $$ and D + → π + ϕ decays, denoted R ϕπ s $$ {R}_{\phi \pi}^s $$ and R ϕπ d $$ {R}_{\phi \pi}^d $$ , are presented. The analysis is performed using a dataset corresponding to an integrated luminosity of 5.4 fb −1 of pp collision data collected with the LHCb experiment. The branching fractions are normalised with respect to the B + → K + J/ψ(→ e + e − ) and B + → K + J/ψ(→ μ + μ − ) decay modes. The combination of the results yields R ϕπ = 1.022 ± 0.012 stat ± 0.048 syst . $$ {R}_{\phi \pi}=1.022\pm 0.012\left(\textrm{stat}\right)\pm 0.048\left(\textrm{syst}\right). $$ The result is compatible with previous measurements of the ϕ → ℓ + ℓ − branching fractions and predictions based on the Standard Model.
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