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Register a new userMeasurement of the CP-violating phase $phi_s$ in $bar{B}^{0}_{s}to D_{s}^{+}D_{s}^{-}$ decays
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We present a measurement of the $CP$-violating weak mixing phase $phi_s$ using the decay $bar{B}^{0}_{s}to D_{s}^{+}D_{s}^{-}$ in a data sample corresponding to $3.0$ fb$^{-1}$ of integrated luminosity collected with the LHCb detector in $pp$ collisions at centre-of-mass energies of 7 and 8 TeV. An analysis of the time evolution of the system, which does not constrain $|lambda|=1$ to allow for the presence of $CP$ violation in decay, yields $phi_s = 0.02 pm 0.17$ (stat) $pm 0.02$ (syst) rad, $|lambda| = 0.91^{+0.18}_{-0.15}$ (stat) $pm0.02$ (syst). This result is consistent with the Standard Model expectation.
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The branching fraction of the decay $B_{s}^{0} rightarrow D_{s}^{(*)+}D_{s}^{(*)-}$ is measured using $pp$ collision data corresponding to an integrated luminosity of $1.0fb^{-1}$, collected using the LHCb detector at a centre-of-mass energy of $7$TeV. It is found to be begin{align*} {mathcal{B}}(B_{s}^{0}rightarrow~D_{s}^{(*)+}D_{s}^{(*)-}) = (3.05 pm 0.10 pm 0.20 pm 0.34)%, end{align*} where the uncertainties are statistical, systematic, and due to the normalisation channel, respectively. The branching fractions of the individual decays corresponding to the presence of one or two $D^{*pm}_{s}$ are also measured. The individual branching fractions are found to be begin{align*} {mathcal{B}}(B_{s}^{0}rightarrow~D_{s}^{*pm}D_{s}^{mp}) = (1.35 pm 0.06 pm 0.09 pm 0.15)%, ewline{mathcal{B}}(B_{s}^{0}rightarrow~D_{s}^{*+}D_{s}^{*-}) = (1.27 pm 0.08 pm 0.10 pm 0.14)%. end{align*} All three results are the most precise determinations to date.
Searches for $CP$ violation in the two-body decays $D_{(s)}^{+}rightarrow h^{+}pi^{0}$ and $D_{(s)}^{+} rightarrow h^{+}eta$ (where $h^{+}$ denotes a $pi^{+}$ or $K^{+}$ meson) are performed using $pp$ collision data collected by the LHCb experiment corresponding to either 9 fb$^{-1}$ or 6 fb$^{-1}$ of integrated luminosity. The $pi^{0}$ and $eta$ mesons are reconstructed using the $e^{+}e^{-}gamma$ final state, which can proceed as three-body decays $pi^{0}rightarrow e^{+}e^{-}gamma$ and $eta rightarrow e^{+}e^{-}gamma$, or via the two-body decays $pi^{0}rightarrow gammagamma$ and $etarightarrowgammagamma$ followed by a photon conversion. The measurements are made relative to the control modes $D_{(s)}^{+}rightarrow K_{S}^{0} h^{+}$ to cancel the production and detection asymmetries. The $CP$ asymmetries are measured to be begin{align} mathcal{A}_{CP}(D^{+}rightarrow pi^{+}pi^{0}) &= (-1.3 pm 0.9 pm 0.6 )%, end{align} begin{align} mathcal{A}_{CP}(D^{+}rightarrow K^{+}pi^{0}) &= (-3.2 pm 4.7 pm 2.1 )%, end{align} begin{align} mathcal{A}_{CP}(D^{+}rightarrow pi^{+}eta) &= (-0.2 pm 0.8 pm 0.4 )%, end{align} begin{align} mathcal{A}_{CP}(D^{+}rightarrow K^{+}eta) &= (-6 pm 10 pm 4 )%, end{align} begin{align} mathcal{A}_{CP}(D_{s}^{+}rightarrow K^{+}pi^{0}) &= (-0.8 pm 3.9 pm 1.2 )%, end{align} begin{align} mathcal{A}_{CP}(D_{s}^{+}rightarrow pi^{+}eta) &= (0.8 pm 0.7 pm 0.5 )%, end{align} begin{align} mathcal{A}_{CP}(D_{s}^{+}rightarrow K^{+}eta) &= (0.9 pm 3.7 pm 1.1 )%, end{align} where the first uncertainties are statistical and the second systematic. These results are consistent with no $CP$ violation and mostly constitute the most precise measurements of $mathcal{A}_{CP}$ in these decay modes to date.
Measurements are presented of the branching fractions of the decays $B_{s}^{0} to D_{s}^{mp} K^{pm}$ and $B^{0} to D_{s}^{-} K^{+}$ relative to the decays $B_{s}^{0} to D_{s}^{-} pi^{+}$ and $B^{0} to D^{-} pi^{+}$, respectively. The data used correspond to an integrated luminosity of 3.0 fb$^{-1}$ of proton-proton collisions. The ratios of branching fractions are $dfrac{mathcal{B}(B_{s}^{0} to D_{s}^{mp} K^{pm})}{mathcal{B}(B_{s}^{0} to D_{s}^{-} pi^{+})} = 0.0752 pm 0.0015 pm 0.0019$ and $dfrac{mathcal{B}(B^{0} to D_{s}^{-} K^{+})}{mathcal{B}(B^{0} to D^{-} pi^{+})} = 0.0129 pm 0.0005 pm 0.0008,$ where the uncertainties are statistical and systematic, respectively.
Using 586 $textrm{pb}^{-1}$ of $e^{+}e^{-}$ collision data acquired at $sqrt{s}=4.170$ GeV with the CLEO-c detector at the Cornell Electron Storage Ring, we report the first observation of $D_{s}^{*+} to D_{s}^{+} e^{+} e^{-}$ with a significance of $5.3 sigma$. The ratio of branching fractions $calB(D_{s}^{*+} to D_{s}^{+} e^{+} e^{-}) / calB(D_{s}^{*+} to D_{s}^{+} gamma)$ is measured to be $[ 0.72^{+0.15}_{-0.13} (textrm{stat}) pm 0.10 (textrm{syst})]%$, which is consistent with theoretical expectations.
Decays of $B_{s}^{0}$ and $overline{B}{}_{s}^{0}$ mesons into $J/psipi^+pi^-$ final states are studied in a data sample corresponding to 1.9 fb$^{-1}$ of integrated luminosity collected with the LHCb detector in 13 TeV $pp$ collisions. A time-dependent amplitude analysis is used to determine the final-state resonance contributions, the $CP$-violating phase $phi_s=-0.057pm 0.060pm 0.011$ rad, the decay-width difference between the heavier mass $B_{s}^{0}$ eigenstate and the $B^{0}$ meson of $-0.050pm 0.004pm 0.004$ ps$^{-1}$, and the $CP$-violating parameter $|lambda|=1.01_{-0.06}^{+0.08}pm0.03$, where the first uncertainty is statistical and the second systematic. These results are combined with previous LHCb measurements in the same decay channel using 7 TeV and 8 TeV $pp$ collisions obtaining $phi_s =0.002pm0.044pm0.012$ rad, and $|lambda| =0.949pm0.036pm0.019$.
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