# Measurement of the CP-violating phase and decay-width difference in $B_s^0\to\psi(2S)\phi$ decays

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## Abstract

A time-dependent angular analysis of $B_s^0\to\psi(2S)\phi$ decays is performed using data recorded by the LHCb experiment. The data set corresponds to an integrated luminosity of 3.0\invfb collected during Run 1 of the LHC. The CP-violating phase and decay-width difference of the $B_s^0$ system are measured to be $\phi_s = 0.23^{+0.29}_{-0.28} \pm 0.02$ rad and $\Delta\Gamma_s = 0.066^{+0.041}_{-0.044} \pm 0.007$ ps$^{-1}$, respectively, where the first uncertainty is statistical and the second systematic. This is the first time that $\phi_s$ and $\Delta\Gamma_s$ have been measured in a decay containing the $\psi(2S)$ resonance.

## Figures and captions

 Definition of helicity angles. fig1a.pdf [29 KiB] HiDef png [47 KiB] Thumbnail [22 KiB] Distribution of $m(\psi(2S) K ^+ K ^- )$ for the selected $B ^0_ s \rightarrow \psi(2S)\phi$ candidates. The total fit model is shown by the solid blue line, which is composed of a sum of two Crystal Ball functions for the signal and an exponential function for the background (long-dashed green line). fig2a.pdf [19 KiB] HiDef png [153 KiB] Thumbnail [121 KiB] Distribution of $m(\psi(2S) K ^+ \pi^-)$ of the selected $B ^0 \rightarrow \psi(2S)K^{*}(892)^{0}$ candidates. The total fit model is shown by the solid blue line, which is composed of a sum of two Crystal Ball functions for the signal and an exponential function for the background (long-dashed green line). fig3a.pdf [20 KiB] HiDef png [161 KiB] Thumbnail [129 KiB] Decay-time efficiency $\varepsilon_{\rm data}^{ B ^0_ s }(t)$ in arbitrary units. fig4a.pdf [16 KiB] HiDef png [91 KiB] Thumbnail [105 KiB] Decay-time and helicity-angle distributions for $B ^0_ s \rightarrow \psi(2S)\phi$ decays (data points) with the one-dimensional projections of the fitted PDF. The solid blue line shows the total signal contribution, which is composed of $C P$ -even (long-dashed red), $C P$ -odd (short-dashed green) and $S$-wave (dash-dotted purple) contributions. fig5a.pdf [20 KiB] HiDef png [209 KiB] Thumbnail [165 KiB] fig5b.pdf [18 KiB] HiDef png [222 KiB] Thumbnail [182 KiB] fig5c.pdf [18 KiB] HiDef png [216 KiB] Thumbnail [171 KiB] fig5d.pdf [19 KiB] HiDef png [211 KiB] Thumbnail [169 KiB] $|A_0|^2$ as a function of the invariant mass squared of the dimuon system, $q^2$. Data points are taken from Ref. [38] ($B ^0_ s \rightarrow \phi\mu^+\mu^-$, circles), Ref. [3] ($B ^0_ s \rightarrow { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} \phi$, diamond) and this paper (square). fig6a.pdf [14 KiB] HiDef png [114 KiB] Thumbnail [118 KiB] Animated gif made out of all figures. PAPER-2016-027.gif Thumbnail

## Tables and captions

 Results of the maximum likelihood fit to the selected $B ^0_ s \rightarrow \psi(2S)\phi$ candidates including all acceptance and resolution effects. The first uncertainty is statistical and the second is systematic, which will be discussed in Section 7. Table_1.pdf [54 KiB] HiDef png [254 KiB] Thumbnail [110 KiB] tex code Correlation matrix of statistical uncertainties. Table_2.pdf [49 KiB] HiDef png [73 KiB] Thumbnail [25 KiB] tex code Summary of statistical and systematic uncertainties. Fields containing a dash (--) correspond to systematic uncertainties that are negligible. Table_3.pdf [62 KiB] HiDef png [119 KiB] Thumbnail [53 KiB] tex code

Created on 18 January 2020.