# Measurements of the branching fractions and $C\!P$ asymmetries of $B^{\pm} \to J\!/\!\psi\, \pi^{\pm}$ and $B^{\pm} \to \psi(2S) \pi^{\pm}$ decays

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## Abstract

A study of B+ to J/psi pi+ and B+ to psi(2S) pi+ decays is performed with data corresponding to 0.37 fb-1 of proton-proton collisions at sqrt(s)=7 TeV. Their branching fractions are found to be B(B+ to J/psi pi+) = (3.88 +- 0.11 +- 0.15) x 10^{-5} and B(B+ to psi(2S) pi+) = (2.52 +- 0.26 +- 0.15) x 10^{-5}, where the first uncertainty is related to the statistical size of the sample and the second quantifies systematic effects. The measured CP asymmetries in these modes are ACP(J/psi pi) = 0.005 +- 0.027 +- 0.011 and ACP(psi(2S) pi) = 0.048 +- 0.090 +- 0.011 with no evidence of direct CP violation seen.

## Figures and captions

 Distribution of $\cos(\theta^*_h)$ versus the invariant mass of $B ^+ \rightarrow { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} \pi ^+$ candidates. The curved structure contains misidentified $B ^+ \rightarrow { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} K ^+$ decays which separate from the $B ^+ \rightarrow { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} \pi ^+$ vertical band for $\cos(\theta^*_h)<0$. The partially reconstructed background, $B\rightarrow { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} K\pi$ enters top left. Fig1.eps [114 KiB] HiDef png [399 KiB] Thumbnail [148 KiB] *.C file Distributions of $B ^\pm \rightarrow { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} h^{\pm}$ invariant mass, overlain by the total fitted PDF (thin line). Pion-like events, with DLL$_{K\pi}<6$ are reconstructed as ${ J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} \pi ^\pm$ and enter in the top plots. All other events are reconstructed as ${ J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} K ^\pm$ and are shown in the bottom plots on a logarithmic scale. $B ^-$ decays are shown on the left, $B ^+$ on the right. The dark [red] curve shows the $B ^\pm \rightarrow { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} \pi ^\pm$ component, the light [green] curve represents $B ^\pm \rightarrow { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} K ^\pm$. The partially reconstructed contributions are shaded. In the lower plots these are visualised with a dark (light) shade for $B ^0_ s$ ( $B ^+$ or $B ^0$ ) decays. In the top plots the shaded component are contributions from $B \rightarrow { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} K ^\pm \pi$ (dark) and $B \rightarrow { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} \pi ^\pm \pi$ (light). Fig2.eps [46 KiB] HiDef png [482 KiB] Thumbnail [63 KiB] *.C file Distributions of $B ^\pm \rightarrow \psi {(2S)} h^{\pm}$ invariant mass. See the caption of Fig. 2 for details. The partially reconstructed background in the pion-like sample is present but negligible yields are found. Fig3.eps [43 KiB] HiDef png [371 KiB] Thumbnail [69 KiB] *.C file Animated gif made out of all figures. PAPER-2011-024.gif Thumbnail

## Tables and captions

 Signal shape parameters from the $B ^\pm \rightarrow \psi h^{\pm}$ fits. Table_1.pdf [43 KiB] HiDef png [71 KiB] Thumbnail [12 KiB] tex code Raw fitted yields. The labels D' and U' refer to the two polarities of the LHCb dipole. Table_2.pdf [41 KiB] HiDef png [96 KiB] Thumbnail [17 KiB] tex code Summary of systematic uncertainties. The statistical fit errors are included for comparison. Table_3.pdf [57 KiB] HiDef png [86 KiB] Thumbnail [13 KiB] tex code

Created on 20 April 2019.Citation count from INSPIRE on 20 April 2019.