Search for B⁺_c→π⁺μ⁺μ⁻ decays and measurement of the branching fraction ratio <i>B</i>(B⁺_c→ψ(2<i>S</i>)π⁺)/<i>B</i>(B⁺_c→<i>J</i>/ψπ⁺)

The first search for nonresonant B+c→π+μ+μ− decays is reported. The analysis uses proton-proton collision data collected with the LHCb detector between 2011 and 2018, corresponding to an integrated luminosity of 9 fb−1. No evidence for an excess of signal events over background is observed and an upper limit is set on the branching fraction ratio B(B+c→π+μ+μ−)/B(B+c→J/ψπ+)&lt;2.1×10−4 at 90% confidence level. Additionally, an updated measurement of the ratio of the B+c→ψ(2S)π+ and B+c→J/ψπ+ branching fractions is reported. The ratio B(B+c→ψ(2S)π+)/B(B+c→J/ψπ+) is measured to be 0.254±0.018±0.003±0.005, where the first uncertainty is statistical, the second systematic, and the third is due to the uncertainties on the branching fractions of the leptonic J/ψ and ψ(2S) decays. This measurement is the most precise to date and is consistent with previous LHCb results

Observation of the<i> B</i>⁺_c → <i>J/ψ</i>π⁺π⁰ decay

The frst observation of the B+c → J/ψπ+π0 decay is reported with high significance using proton-proton collision data, corresponding to an integrated luminosity of 9 fb−1, collected with the LHCb detector at centre-of-mass energies of 7, 8, and 13 TeV. The ratio ofits branching fraction relative to the B+c → J/ψπ+ channel is measured to beBB+c →J/ψπ+π0BB+c →J/ψπ+= 2.80 ± 0.15 ± 0.11 ± 0.16 ,where the first uncertainty is statistical, the second systematic and the third related to imprecise knowledge of the branching fractions for B+ → J/ψK∗+ and B+c → J/ψπ+ decays, which are used to determine the π0 detection efficiency. The π+π0 mass spectrum is found to be consistent with the dominance of an intermediate ρ+ contribution in accordance witha model based on QCD factorisation.<br/

Study of <i>CP</i> violation in <i>B</i>⁰_(s)→<i>DK</i>^∗(892)⁰ decays with <i>D</i>→<i>K</i>π(ππ), ππ(ππ), and <i>KK</i> final states

A measurement of CP-violating observables associated with the interference of B0→D0K∗(892)0 and B0→D¯0K∗(892)0 decay amplitudes is performed in the D0→K∓π±(π+π−), D0→π+π−(π+π−), and D0→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 B0s→D0K¯∗(892)0 and B0s→D¯0K¯∗(892)0 are also measured, but no evidence for interference is found. The B0 observables are used to constrain the parameter space of the CKM angle γ and the hadronic parameters rDK∗B0 and δDK∗B0 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

A measurement of ΔΓs\Delta \Gamma_{s}

Using a dataset corresponding to 9 fb$^{−1}$ of integrated luminosity collected with the LHCb detector between 2011 and 2018 in proton-proton collisions, the decay-time distributions of the decay modes ${B}_s^0\to J/{\psi \eta}^{\prime }$ and ${B}_s^0\to J/\psi {\pi}^{+}{\pi}^{-}$ are studied. The decay-width difference between the light and heavy mass eigenstates of the ${B}_s^0$ meson is measured to be ∆Γ$_{s}$ = 0.087 ± 0.012 ± 0.009 ps$^{−1}$, where the first uncertainty is statistical and the second systematic.[graphic not available: see fulltext]Using a dataset corresponding to $9~\mathrm{fb}^{-1}$ of integrated luminosity collected with the LHCb detector between 2011 and 2018 in proton-proton collisions, the decay-time distributions of the decay modes $B_s^0 \rightarrow J/\psi \eta'$ and $B_s^0 \rightarrow J/\psi \pi^{+} \pi^{-}$ are studied. The decay-width difference between the light and heavy mass eigenstates of the $B_s^0$ meson is measured to be $\Delta \Gamma_s = 0.087 \pm 0.012 \pm 0.009 \, \mathrm{ps}^{-1}$, where the first uncertainty is statistical and the second systematic

Observation of Cabibbo-suppressed two-body hadronic decays and precision mass measurement of the Ωc0\Omega_{c}^{0} baryon

International audienceThe first observation of the singly Cabibbo-suppressed $\Omega_{c}^{0}\to\Omega^{-}K^{+}$ and $\Omega_{c}^{0}\to\Xi^{-}\pi^{+}$ decays is reported, using proton-proton collision data at a centre-of-mass energy of $13\,{\rm TeV}$, corresponding to an integrated luminosity of $5.4\,{\rm fb}^{-1}$, collected with the LHCb detector between 2016 and 2018. The branching fraction ratios are measured to be $\frac{\mathcal{B}(\Omega_{c}^{0}\to\Omega^{-}K^{+})}{\mathcal{B}(\Omega_{c}^{0}\to\Omega^{-}\pi^{+})}=0.0608\pm0.0051({\rm stat})\pm 0.0040({\rm syst})$, $\frac{\mathcal{B}(\Omega_{c}^{0}\to\Xi^{-}\pi^{+})}{\mathcal{B}(\Omega_{c}^{0}\to\Omega^{-}\pi^{+})}=0.1581\pm0.0087({\rm stat})\pm0.0043({\rm syst})\pm0.0016({\rm ext})$. In addition, using the $\Omega_{c}^{0}\to\Omega^{-}\pi^{+}$ decay channel, the $\Omega_{c}^{0}$ baryon mass is measured to be $M(\Omega_{c}^{0})=2695.28\pm0.07({\rm stat})\pm0.27({\rm syst})\pm0.30({\rm ext})\,{\rm MeV}/c^{2}$, improving the precision of the previous world average by a factor of four

Observation and branching fraction measurement of the decay Ξb−→Λb0π−\Xi_b^-\to\Lambda_b^0\pi^-

International audienceThe decay $\Xi_b^-\to\Lambda_b^0\pi^-$ is observed using a proton-proton collision data sample collected at center-of-mass energy $\sqrt{s}=13$ TeV with the LHCb detector, corresponding to an integrated luminosity of 5.5 fb$^{-1}$. This process is mediated by the $s\to u\bar{u}d$ quark-level transition, where the $b$ quark in the $\Xi_b^-$ baryon is a spectator in the decay. Averaging the results obtained using the two $\Lambda_b^0$ decay modes, $\Lambda_b^0\to\Lambda_c^+\pi^-$ and $\Lambda_b^0\to\Lambda_c^+\pi^-\pi^+\pi^-$, the relative production ratio is measured to be $(f_{\Xi_b^-}/f_{\Lambda_b^0}){\cal{B}}(\Xi_b^-\to\Lambda_b^0\pi^-)=(7.3\pm0.8\pm0.6)\times10^{-4}$. Here the uncertainties are statistical and systematic, respectively, and $f_{\Xi_b^-}(f_{\Lambda_b^0})$ is the fragmentation fraction for a $b$ quark into a $\Xi_b^-$ ($\Lambda_b^0$) baryon. Using an independent measurement of $f_{\Xi_b^-}/f_{\Lambda_b^0}$, the branching fraction ${\cal{B}}(\Xi_b^-\to\Lambda_b^0\pi^-)=(0.89\pm0.10\pm0.07\pm0.29)\%$ is obtained, where the last uncertainty is due to the assumed SU(3) flavor symmetry in the determination of $f_{\Xi_b^-}/f_{\Lambda_b^0}$

Modification of χc1\chi_{c1}(3872) and ψ\psi(2SS) production in ppPb collisions at sNN=8.16\sqrt{s_{NN}} = 8.16 TeV

The LHCb Collaboration measures production of the exotic hadron χc1(3872) in proton-nucleus collisions for the first time. Comparison with the charmonium state ψ(2S) suggests that the exotic χc1(3872) experiences different dynamics in the nuclear medium than conventional hadrons, and comparison with data from proton-proton collisions indicates that the presence of the nucleus may modify χc1(3872) production rates. This is the first measurement of the nuclear modification factor of an exotic hadron.The LHCb collaboration measures production of the exotic hadron $\chi_{c1}$(3872) in proton-nucleus collisions for the first time. Comparison with the charmonium state $\psi$(2$S$) suggests that the exotic $\chi_{c1}$(3872) experiences different dynamics in the nuclear medium than conventional hadrons, and comparison with data from proton-proton collisions indicates that the presence of the nucleus may modify $\chi_{c1}$(3872) production rates. This is the first measurement of the nuclear modification factor of an exotic hadron

Observation of Ξb0→Ξc+Ds−\Xi_b^0 \rightarrow \Xi_c^+ D_s^- and Ξb−→Ξc0Ds−\Xi_b^- \rightarrow \Xi_c^0 D_s^- decays

International audienceThe $\Xi_b^0 \rightarrow \Xi_c^+ D_s^-$ and $\Xi_b^- \rightarrow \Xi_c^0 D_s^-$ decays are observed for the first time using proton-proton collision data collected by the LHCb experiment at a centre-of-mass energy of $\sqrt{s}=13\mathrm{TeV}$, corresponding to an integrated luminosity of $5.1\mathrm{fb}^{-1}$. The relative branching fractions times the beauty-baryon production cross-sections are measured to be \begin{align*} \mathcal{R}\left(\frac{\Xi_b^0}{\Lambda_b^0}\right) \equiv \frac{\sigma\left(\Xi_b^0\right)}{\sigma\left(\Lambda_b^0\right)} \times \frac{\mathcal{B}\left(\Xi_b^0 \rightarrow \Xi_c^+ D_s^-\right)}{\mathcal{B}\left(\Lambda_b^0 \rightarrow \Lambda_c^0 D_s^-\right)} =(15.8\pm1.1\pm0.6\pm7.7)\%, \mathcal{R}\left(\frac{\Xi_b^-}{\Lambda_b^0}\right) \equiv \frac{\sigma\left(\Xi_b^-\right)}{\sigma\left(\Lambda_b^0\right)} \times \frac{\mathcal{B}\left(\Xi_b^- \rightarrow \Xi_c^0 D_s^-\right)}{\mathcal{B}\left(\Lambda_b^0 \rightarrow \Lambda_c^0 D_s^-\right)} =(16.9\pm1.3\pm0.9\pm4.3)\%, \end{align*} where the first uncertainties are statistical, the second systematic, and the third due to the uncertainties on the branching fractions of relevant charm-baryon decays. The masses of $\Xi_b^0$ and $\Xi_b^-$ baryons are measured to be $m_{\Xi_b^0}=5791.12\pm0.60\pm0.45\pm0.24\mathrm{MeV}/c^2$ and $m_{\Xi_b^-}=5797.02\pm0.63\pm0.49\pm0.29\mathrm{MeV}/c^2$, where the uncertainties are statistical, systematic, and those due to charm-hadron masses, respectively