Amplitude analysis of the B(s)0→K∗0K‾∗0B^0_{(s)} \to K^{*0} \overline{K}^{*0} decays and measurement of the branching fraction of the B0→K∗0K‾∗0B^0 \to K^{*0} \overline{K}^{*0} decay

International audienceThe ${B}^0\to {K}^{\ast 0}{\overline{K}}^{\ast 0}$ and ${B}_s^0\to {K}^{\ast 0}{\overline{K}}^{\ast 0}$ decays are studied using proton-proton collision data corresponding to an integrated luminosity of 3 fb$^{−1}$. An untagged and timeintegrated amplitude analysis of B_{( s}_{)}^{0}  → (K$^{+}$π$^{−}$)(K$^{−}$π$^{+}$) decays in two-body invariant mass regions of 150 MeV/c$^{2}$ around the K$^{∗0}$ mass is performed. A stronger longitudinal polarisation fraction in the ${B}^0\to {K}^{\ast 0}{\overline{K}}^{\ast 0}$ decay, f$_{L}$ = 0.724 ± 0.051 (stat) ± 0.016 (syst), is observed as compared to f$_{L}$ = 0.240 ± 0.031 (stat) ± 0.025 (syst) in the ${B}_s^0\to {K}^{\ast 0}{\overline{K}}^{\ast 0}$ decay. The ratio of branching fractions of the two decays is measured and used to determine $\mathrm{\mathcal{B}}\left({B}^0\to {K}^{\ast 0}{\overline{K}}^{\ast 0}\right)=\left(8.0\pm 0.9\left(\mathrm{stat}\right)\pm 0.4\left(\mathrm{syst}\right)\right)\times {10}^{-7}$

Measurement of CPCP-violating and mixing-induced observables in Bs0→ϕγB_s^0 \to \phi\gamma decays

International audienceA time-dependent analysis of the Bs0→ϕγ decay rate is performed to determine the CP -violating observables Sϕγ and Cϕγ and the mixing-induced observable AϕγΔ. The measurement is based on a sample of pp collision data recorded with the LHCb detector, corresponding to an integrated luminosity of 3  fb-1 at center-of-mass energies of 7 and 8 TeV. The measured values are Sϕγ=0.43±0.30±0.11, Cϕγ=0.11±0.29±0.11, and AϕγΔ=-0.67-0.41+0.37±0.17, where the first uncertainty is statistical and the second systematic. This is the first measurement of the observables S and C in radiative Bs0 decays. The results are consistent with the standard model predictions

Measurement of CP violation in the Bs0→ϕϕ {B}_s^0\to \phi \phi decay and search for the B0→ϕϕB^0\rightarrow \phi\phi decay

International audienceA measurement of the time-dependent CP-violating asymmetry in ${B}_s^0\to \phi \phi$ 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 $\sqrt{s}$ = 7 TeV in 2011, 8 TeV in 2012 and 13 TeV in 2015 and 2016, a signal yield of around 9000 ${B}_s^0\to \phi \phi$ decays is obtained. The CP-violating phase ${\phi}_s^{s\overline{s}s}$ 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 $\overline{b}\to \overline{s}s\overline{s}s$ transitions. Finally, a limit on the branching fraction of the B$^{0}$ → ϕϕ decay is determined to be $\mathcal{B}\left({B}^0\to \phi \phi \right)<2.7\times {10}^{-8}$ at 90 % confidence level

Observation of an excited Bc+B_c^+ state

International audienceUsing pp collision data corresponding to an integrated luminosity of 8.5  fb-1 recorded by the LHCb experiment at center-of-mass energies of s=7, 8, and 13 TeV, the observation of an excited Bc+ state in the Bc+π+π- invariant-mass spectrum is reported. The observed peak has a mass of 6841.2±0.6(stat)±0.1(syst)±0.8(Bc+)  MeV/c2, where the last uncertainty is due to the limited knowledge of the Bc+ mass. It is consistent with expectations of the Bc*(2S31)+ state reconstructed without the low-energy photon from the Bc*(1S31)+→Bc+γ decay following Bc*(2S31)+→Bc*(1S31)+π+π-. A second state is seen with a global (local) statistical significance of 2.2σ (3.2σ) and a mass of 6872.1±1.3(stat)±0.1(syst)±0.8(Bc+)  MeV/c2, and is consistent with the Bc(2S10)+ state. These mass measurements are the most precise to date

Observation of Several Sources of CPCP Violation in B+→π+π+π−B^+ \to \pi^+ \pi^+ \pi^- Decays

International audienceObservations are reported of different sources of CP violation from an amplitude analysis of B+→π+π+π- decays, based on a data sample corresponding to an integrated luminosity of 3  fb-1 of pp collisions recorded with the LHCb detector. A large CP asymmetry is observed in the decay amplitude involving the tensor f2(1270) resonance, and in addition significant CP violation is found in the π+π-S wave at low invariant mass. The presence of CP violation related to interference between the π+π-S wave and the P wave B+→ρ(770)0π+ amplitude is also established; this causes large local asymmetries but cancels when integrated over the phase space of the decay. The results provide both qualitative and quantitative new insights into CP -violation effects in hadronic B decays

Measurement of the mass difference between neutral charm-meson eigenstates

International audienceWe report a measurement of the mass difference between neutral charm-meson eigenstates using a novel approach that enhances sensitivity to this parameter. We use 2.3×106 D0→KS0π+π- decays reconstructed in proton-proton collisions collected by the LHCb experiment in 2011 and 2012. Allowing for CP violation in mixing and in the interference between mixing and decay, we measure the CP-averaged normalized mass difference xCP=[2.7±1.6(stat)±0.4(syst)]×10-3 and the CP-violating parameter Δx=[-0.53±0.70(stat)±0.22(syst)]×10-3. The results are consistent with CP symmetry. These determinations are the most precise from a single experiment and, combined with current world-average results, yield the first evidence that the masses of the neutral charm-meson eigenstates differ

Near-threshold DDˉD\bar{D} spectroscopy and observation of a new charmonium state

International audienceUsing proton-proton collision data, corresponding to an integrated luminosity of 9 fb$^{−1}$, collected with the LHCb detector between 2011 and 2018, a new narrow charmonium state, the X(3842) resonance, is observed in the decay modes $\mathrm{X}(3842)\to {D}^0{\overline{D}}^0$ and X(3842) → D$^{+}$D$^{−}$. The mass and the natural width of this state are measured to b