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Register a new userMeasurement of $CP$ violation in $B^0to D^{*pm} D^{mp}$ decays
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The decay-time-dependent $CP$ asymmetry in $B^0 to D^{*pm}D^{mp}$ decays is measured using a data set corresponding to an integrated luminosity of $9$fb$^{-1}$ recorded by the LHCb detector in proton-proton collisions at centre-of-mass energies of 7, 8 and 13 TeV. The $CP$ parameters are measured as $ S_{D^*D} = -0.861 pm 0.077,text{(stat)} pm 0.019 ,text{(syst)},, $ $ Delta S_{D^*D} = 0.019 pm 0.075 ,text{(stat)} pm 0.012 ,text{(syst)} ,, $ $ C_{D^*D} = -0.059 pm 0.092 ,text{(stat)} pm 0.020 ,text{(syst)} ,, $ $ Delta C_{D^*D} = -0.031 pm 0.092 ,text{(stat)} pm 0.016 ,text{(syst)} ,, $ $ {cal A}_{D^*D} = 0.008 pm 0.014 ,text{(stat)} pm 0.006 ,text{(syst)},. $ The analysis provides the most precise single measurement of $CP$ violation in this decay channel to date. All parameters are consistent with their current world average values.
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A measurement of the $CP$ asymmetries $S_{f}$ and $S_{bar{f}}$ in $B^0to D^{mp}pi^{pm}$ decays is reported. The decays are reconstructed in a dataset collected with the LHCb experiment in proton-proton collisions at centre-of-mass energies of 7 and 8 TeV and corresponding to an integrated luminosity of $3.0 rm{ fb}^{-1}$. The $CP$ asymmetries are measured to be $S_{f} = 0.058 pm 0.020 (rm{stat}) pm 0.011(rm{syst})$ and $S_{bar{f}} = 0.038pm 0.020 (text{stat})pm 0.007 (text{syst})$. These results are in agreement with, and more precise than, previous determinations. They are used to constrain $|sinleft(2beta+gammaright)|$ and $gamma$ to intervals that are consistent with the current world-average values.
We report on measurements of the time-dependent CP violating observables in $B^0_srightarrow D^{mp}_s K^{pm}$ decays using a dataset corresponding to 1.0 fb$^{-1}$ of pp collisions recorded with the LHCb detector. We find the CP violating observables $C_f=0.53pm0.25pm0.04$, $A^{DeltaGamma}_f=0.37pm0.42pm0.20$, $A^{DeltaGamma}_{bar{f}}=0.20pm0.41pm0.20$, $S_f=-1.09pm0.33pm0.08$, $S_{bar{f}}=-0.36pm0.34pm0.08$, where the uncertainties are statistical and systematic, respectively. Using these observables together with a recent measurement of the $B^0_s$ mixing phase $-2beta_s$ leads to the first extraction of the CKM angle $gamma$ from $B^0_s rightarrow D^{mp}_s K^{pm}$ decays, finding $gamma$ = (115$_{-43}^{+28}$)$^circ$ modulo 180$^circ$ at 68% CL, where the error contains both statistical and systematic uncertainties.
The $CP$ violation observables $S$ and $C$ in the decay channel $B^0 !rightarrow D^+ D^-$ are determined from a sample of proton-proton collisions at center-of-mass energies of 7 and 8 TeV, collected by the LHCb experiment and corresponding to an integrated luminosity of 3 fb$^{-1}$. The observable $S$ describes $CP$ violation in the interference between mixing and the decay amplitude, and $C$ parametrizes direct $CP$ violation in the decay. The following values are obtained from a flavor-tagged, decay-time-dependent analysis: begin{align*} S &= -0.54 , ^{+0.17}_{-0.16} , text{(stat)} pm 0.05 , text{(syst)},, ewline C &= phantom{-}0.26 , ^{+0.18}_{-0.17} , text{(stat)} pm 0.02 , text{(syst)},. end{align*} These values provide evidence for $CP$ violation at a significance level of 4.0 standard deviations. The phase shift due to higher-order Standard Model corrections is constrained to a small value of begin{align*} Deltaphi = -0.16,^{+0.19}_{-0.21},text{rad},. end{align*}
Measurements of $CP$ observables in $B^pm rightarrow D^{(*)} K^pm$ and $B^pm rightarrow D^{(*)} pi^pm$ decays are presented, where $D^{(*)}$ indicates a neutral $D$ or $D^*$ meson that is an admixture of $D^{(*)0}$ and $bar{D}^{(*)0}$ states. Decays of the $D^*$ meson to the $Dpi^0$ and $Dgamma$ final states are partially reconstructed without inclusion of the neutral pion or photon, resulting in distinctive shapes in the $B$ candidate invariant mass distribution. Decays of the $D$ meson are fully reconstructed in the $K^pm pi^mp$, $K^+ K^-$ and $pi^+ pi^-$ final states. The analysis uses a sample of charged $B$ mesons produced in $pp$ collisions collected by the LHCb experiment, corresponding to an integrated luminosity of 2.0, 1.0 and 2.0 fb$^{-1}$ taken at centre-of-mass energies of $sqrt{s}$ = 7, 8 and 13 TeV, respectively. The study of $B^{pm} to D^{*} K^{pm}$ and $B^{pm} to D^{*} pi^{pm}$ decays using a partial reconstruction method is the first of its kind, while the measurement of $B^{pm} to D K^{pm}$ and $B^{pm} to D pi^{pm}$ decays is an update of previous LHCb measurements. The $B^{pm} to D K^{pm}$ results are the most precise to date.
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