Measurement of prompt D+D^+ and Ds+D^+_{s} production in pPbp\mathrm{Pb} collisions at sNN=5.02 \sqrt {s_{\mathrm{NN}}}=5.02\,TeV

International audienceThe production of prompt $D^+$ and $D^+_{s}$ mesons is studied in proton-lead collisions at a centre-of-mass energy of $\sqrt {s_{\mathrm{NN}}}=5.02\,$TeV. The data sample corresponding to an integrated luminosity of $(1.58\pm0.02)\mathrm{nb}^{-1}$ is collected by the LHCb experiment at the LHC. The differential production cross-sections are measured using $D^+$ and $D^+_{s}$ candidates with transverse momentum in the range of $0<p_{\mathrm{T}} <14\,\mathrm{GeV}/c$ and rapidities in the ranges of $1.5<y^*<4.0$ and $-5.0<y^*<-2.5$ in the nucleon-nucleon centre-of-mass system. For both particles, the nuclear modification factor and the forward-backward production ratio are determined. These results are compared with theoretical models that include initial-state nuclear effects. In addition, measurements of the cross-section ratios between $D^+$, $D^+_{s}$ and $D^0$ mesons are presented, providing a baseline for studying the charm hadronization in lead-lead collisions at LHC energies

Measurement of prompt D+D^+ and Ds+D^+_{s} production in pPbp\mathrm{Pb} collisions at sNN=5.02 \sqrt {s_{\mathrm{NN}}}=5.02\,TeV

International audienceThe production of prompt $D^+$ and $D^+_{s}$ mesons is studied in proton-lead collisions at a centre-of-mass energy of $\sqrt {s_{\mathrm{NN}}}=5.02\,$TeV. The data sample corresponding to an integrated luminosity of $(1.58\pm0.02)\mathrm{nb}^{-1}$ is collected by the LHCb experiment at the LHC. The differential production cross-sections are measured using $D^+$ and $D^+_{s}$ candidates with transverse momentum in the range of $0<p_{\mathrm{T}} <14\,\mathrm{GeV}/c$ and rapidities in the ranges of $1.5<y^*<4.0$ and $-5.0<y^*<-2.5$ in the nucleon-nucleon centre-of-mass system. For both particles, the nuclear modification factor and the forward-backward production ratio are determined. These results are compared with theoretical models that include initial-state nuclear effects. In addition, measurements of the cross-section ratios between $D^+$, $D^+_{s}$ and $D^0$ mesons are presented, providing a baseline for studying the charm hadronization in lead-lead collisions at LHC energies

Evidence for the decays B0→Dˉ(∗)0ϕB^{0}\rightarrow\bar{D}^{(*)0}\phi and updated measurements of the branching fractions of the Bs0→Dˉ(∗)0ϕB^{0}_{s}\rightarrow\bar{D}^{(*)0}\phi decays

International audienceEvidence for the decays $B^{0}\rightarrow\bar{D}^{0}\phi$ and $B^{0} \rightarrow \bar{D}^{*0}\phi$ is reported with a significance of 3.6$\,\sigma$ and 4.3$\,\sigma$, respectively. The analysis employs $pp$ collision data at centre-of-mass energies $\sqrt{s}=7$, 8 and 13 TeV collected by the LHCb detector and corresponding to an integrated luminosity of 9 $\rm{fb}^{-1}$. The branching fractions are measured to be $\mathcal{B}(B^{0}\rightarrow\bar{D}^{0}\phi) = (7.7\pm2.1\pm0.7\pm0.7)\times10^{-7}$, $\mathcal{B}(B^{0} \rightarrow \bar{D}^{*0}\phi)=(2.2\pm0.5\pm0.2\pm0.2)\times10^{-6}$. In these results, the first uncertainties are statistical, the second systematic, and the third is related to the branching fraction of the $B^{0}\rightarrow\bar{D}^{0}K^{+}K^{-}$ decay, used for normalisation. By combining the branching fractions of the decays $B^{0}\rightarrow\bar{D}^{(*)0}\phi$ and $B^{0}\rightarrow\bar{D}^{(*)0}\omega$, the $\omega$-$\phi$ mixing angle $\delta$ is constrained to be $\tan^2\delta = (3.6\pm0.7\pm0.4)\times10^{-3}$, where the first uncertainty is statistical and the second systematic. An updated measurement of the branching fractions of the $B^{0}_{s} \rightarrow \bar{D}^{(*)0}\phi$ decays, which can be used to determine the CKM angle $\gamma$, leads to $\mathcal{B}(B^{0}_{s}\rightarrow\bar{D}^{0}\phi)=(2.30\pm0.10 \pm 0.11\pm0.20)\times10^{-5}$, $\mathcal{B}(B^{0}_{s}\rightarrow\bar{D}^{*0}\phi) =(3.17\pm0.16 \pm 0.17 \pm 0.27)\times10^{-5}$

Study of the Bose-Einstein correlations of same-sign pions in proton-lead collisions

International audienceCorrelations of same-sign charged particles are analysed using proton-lead collision data collected by the LHCb experiment at a nucleon-nucleon centre-of-mass energy of 5.02 TeV, corresponding to an integrated luminosity of 1.06 nb-1. Bose-Einstein correlations are observed in the form of an enhancement of pair production for same-sign charged pions with a small four-momentum difference squared. The dependence of the correlation radius and the intercept parameter on the reconstructed charged-particle multiplicity is investigated. The measured correlation radii scale linearly with the cube root of the reconstructed charged-particle multiplicity, being compatible with predictions of hydrodynamic models on the collision system evolution

Measurement of CP violation in B0→ψ(→ℓ+ℓ−)KS0(→π+π−)B^0\to\psi(\to\ell^+\ell^-)K^0_S(\to\pi^+\pi^-) decays

International audienceA measurement of time-dependent CP violation in the decays of $B^0$ and $\overline{B}^0$ mesons to the final states $J/\psi(\to\mu^+\mu^-)K^0_S$, $\psi(2S)(\to\mu^+\mu^-)K^0_S$ and $J/\psi(\to e^+e^-)K^0_S$ with $K^0_S\to\pi^+\pi^-$ is presented. The data correspond to an integrated luminosity of 6 fb${}^{-1}$ collected at a centre-of-mass energy of $\sqrt{s}=13$ TeV with the LHCb detector. The CP-violation parameters are measured to be \begin{align*} S_{\psi K^0_S} &= 0.717 \pm 0.013 (\text{stat}) \pm 0.008 (\text{syst}), \\ C_{\psi K^0_S} &= 0.008 \pm 0.012 (\text{stat}) \pm 0.003 (\text{syst}). \end{align*} This measurement of $S_{\psi K^0_S}$ represents the most precise single measurement of the CKM angle $\beta$ to date and is more precise than the current world average. In addition, measurements of the CP-violation parameters of the individual channels are reported and a combination with the LHCb Run 1 measurements is performed

Measurement of the CKM angle γ\gamma in the B0→DK∗0B^0 \to DK^{*0} channel using self-conjugate D→KS0h+h−D \to K_S^0 h^+ h^- decays

International audienceA model-independent study of CP violation in $B^0 \to DK^{*0}$ decays is presented using data corresponding to an integrated luminosity of 9fb$^{-1}$ collected by the LHCb experiment at centre-of-mass energies of $\sqrt{s}=7, \, 8$ and $13$TeV. The CKM angle $\gamma$ is determined by examining the distributions of signal decays in phase-space bins of the self-conjugate $D \to K_S^0 h^+ h^-$ decays, where $h = \pi, K$. Observables related to CP violation are measured and the angle $\gamma$ is determined to be $\gamma=(49^{+ 23}_{-18})^\circ$. Measurements of the amplitude ratio and strong-phase difference between the favoured and suppressed $B^0$ decays are also presented

A measurement of ΔΓs\Delta \Gamma_{s}

International audienceUsing 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

Determination of short- and long-distance contributions in B0→K∗0μ+μ−B^{0}\to K^{*0}\mu^+\mu^- decays

International audienceAn amplitude analysis of the $B^0 \to K^{*0} \mu^+\mu^-$ decay is presented. The analysis is based on data collected by the LHCb experiment from proton-proton collisions at $\sqrt{s} = 7,\,8$ and $13$ TeV, corresponding to an integrated luminosity of $4.7$ fb$^{-1}$. For the first time, Wilson coefficients and non-local hadronic contributions are accessed directly from the unbinned data, where the latter are parameterised as a function of $q^2$ with a polynomial expansion. Wilson coefficients and non-local hadronic parameters are determined under two alternative hypotheses: the first relies on experimental information alone, while the second one includes information from theoretical predictions for the non-local contributions. Both models obtain similar results for the parameters of interest. The overall level of compatibility with the Standard Model is evaluated to be between 1.8 and 1.9 standard deviations when looking at the $\mathcal{C}_9$ Wilson coefficient alone, and between 1.3 and 1.4 standard deviations when considering the full set of $\mathcal{C}_9, \, \mathcal{C}_{10}, \, \mathcal{C}_9^\prime$ and $\mathcal{C}_{10}^\prime$ Wilson coefficients. The ranges reflect the theoretical assumptions made in the analysis

Study of Bc+→χcπ+B_c^+ \rightarrow \chi_c \pi^+ decays

International audienceA study of $B_c^+ \rightarrow \chi_c \pi^+$ decays is reported using proton-proton collision data, collected with the LHCb detector at centre-of-mass energies of 7, 8, and 13 TeV, corresponding to an integrated luminosity of 9fb$^{-1}$. The decay $B_c^+ \rightarrow \chi_{c2} \pi^+$ is observed for the first time, with a significance exceeding seven standard deviations. The relative branching fraction with respect to the $B_c^+ \rightarrow J/\psi \pi^+$ decay is measured to be $$\frac{\mathcal{B}_{B_c^+ \rightarrow \chi_{c2} \pi^+}} {\mathcal{B}_{B_c^+ \rightarrow J/\psi \pi^+}} = 0.37 \pm 0.06 \pm 0.02 \pm 0.01 ,$$ where the first uncertainty is statistical, the second is systematic, and the third is due to the knowledge of the $\chi_c \rightarrow J/\psi \gamma$ branching fraction. No significant $B_c^+ \rightarrow \chi_{c1} \pi^+$ signal is observed and an upper limit for the relative branching fraction for the $B_c^+ \rightarrow \chi_{c1} \pi^+$ and $B_c^+ \rightarrow \chi_{c2} \pi^+$ decays of $$\frac{\mathcal{B}_{B_c^+ \rightarrow \chi_{c1} \pi^+}} {\mathcal{B}_{B_c^+ \rightarrow \chi_{c2} \pi^+}} < 0.49$$ is set at the 90% confidence level