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Register a new userObservation of $B^{pm} to psi(2S) pi^{pm}$ and search for direct CP-violation
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We report the first observation of $B^{pm}topsi(2S)pi^{pm}$, a Cabibbo- and color-suppressed decay. This analysis is based on $657times10^{6}$ $Boverline B$ events collected at the $Upsilon(4S)$ resonance with the Belle detector at the KEKB energy-asymmetric $e^+e^-$ collider. The measured branching fraction is ($2.44 pm 0.22 pm 0.20$)$times 10^{-5}$ and the charge asymmetry is $mathcal{A}=0.022 pm 0.085 pm 0.016$. The ratio of the branching fractions $mathcal {B}(B^{pm} to psi(2S) pi^{pm})$$/ mathcal {B}(B^{pm} to psi(2S) K^{pm})$ $ = (3.99 pm 0.36pm 0.17)%$ is also determined.
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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.
A first study of CP violation in the decay modes $B^pmto [K^0_{rm S} K^pm pi^mp]_D h^pm$ and $B^pmto [K^0_{rm S} K^mp pi^pm]_D h^pm$, where $h$ labels a $K$ or $pi$ meson and $D$ labels a $D^0$ or $overline{D}^0$ meson, is performed. The analysis uses the LHCb data set collected in $pp$ collisions, corresponding to an integrated luminosity of 3 fb$^{-1}$. The analysis is sensitive to the CP-violating CKM phase $gamma$ through seven observables: one charge asymmetry in each of the four modes and three ratios of the charge-integrated yields. The results are consistent with measurements of $gamma$ using other decay modes.
We analyze the partial rate asymmetry in $B^{pm} to P {bar P} pi^{pm}$ decays ($ P = pi^+, K ^+, pi^0, eta$) which results from the interference of the nonresonant decay amplitude and the resonant amplitude for $B^{pm} to chi_{c0} pi^{pm} $ followed by the decay $chi_{c0} to P {bar P} $. The CP violating phase $gamma$ can be extracted from the measured asymmetry. We find that the partial rate asymmetry for $B^pm to pi^+ pi^- pi^pm$ is $0.33~sin gamma$, while for $B^pm to K^+ K^-pi^pm$ it amounts $0.45~ sin gamma$.
The $B^{pm}$ meson production asymmetry in $pp$ collisions is measured using $B^+ to bar{D}^0 pi^+$ decays. The data were recorded by the LHCb experiment during Run 1 of the LHC at centre-of-mass energies of $sqrt{s}=$ 7 and 8 TeV. The production asymmetries, integrated over transverse momenta in the range $2 < p_{rm T} < 30$ GeV/$c$, and rapidities in the range $2.1 < y < 4.5$, are measured to be begin{align*} mathcal{A}_{rm prod}(B^+,sqrt{s}=7~{rm TeV}) &= (-0.41 pm 0.49 pm 0.10) times 10^{-2}, mathcal{A}_{rm prod}(B^+,sqrt{s}=8~{rm TeV}) &= (-0.53 pm 0.31 pm 0.10) times 10^{-2}, end{align*} where the first uncertainties are statistical and the second are systematic. These production asymmetries are used to correct the raw asymmetries of $B^{+} to J/psi K^{+}$ decays, thus allowing a measurement of the $CP$ asymmetry, begin{equation*} mathcal{A}_{CP} = (0.09 pm 0.27 pm 0.07) times 10^{-2}. end{equation*}
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