# Measurement of ${C\!P}$ violation parameters and polarisation fractions in ${B_s^0\to J/\psi \overline{K}^{*0}}$ decays

[to restricted-access page]

## Abstract

The first measurement of ${C\!P}$ asymmetries in the decay ${B_s^0\to J/\psi \overline{K}^{*}(892)^{0}}$ and an updated measurement of its branching fraction and polarisation fractions are presented. The results are obtained using data corresponding to an integrated luminosity of $3.0\,fb^{-1}$ of proton-proton collisions recorded with the LHCb detector at centre-of-mass energies of $7$ and $8\,\mathrm{TeV}$. Together with constraints from ${B^0\to J/\psi \rho^0}$, the results are used to constrain additional contributions due to penguin diagrams in the ${C\!P}$-violating phase ${{\phi}_{s}}$, measured through ${B_s^0}$ decays to charmonium.

## Figures and captions

 Decay topologies contributing to the $B^0_s\to { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} \phi$ channel (a,b) and $B^0_s\to { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} \overline{ K}{} ^{*0}$ channel (c,d). The tree diagrams (a,c) are shown on the left and the penguin diagrams (b,d) on the right. Fig1a.pdf [6 KiB] HiDef png [99 KiB] Thumbnail [24 KiB] *.C file Fig1b.pdf [8 KiB] HiDef png [115 KiB] Thumbnail [27 KiB] *.C file Fig1c.pdf [9 KiB] HiDef png [102 KiB] Thumbnail [25 KiB] *.C file Fig1d.pdf [11 KiB] HiDef png [117 KiB] Thumbnail [28 KiB] *.C file The ${ J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} K^- \pi^+$ invariant mass distribution with the sum of the fit projections in the 20 $m_{ K^- \pi^+ }$ and $\cos(\theta_{\mu})$ bins. Points with error bars show the data. The projection of the fit result is represented by the solid blue line, and the contributions from the different components are detailed in the legend. At this scale the contribution of the $\Lambda^0_b \to { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} p \pi^-$ is barely visible. All the other peaking background components are subtracted as described in the text. Fig2.pdf [32 KiB] HiDef png [291 KiB] Thumbnail [90 KiB] *.C file Representation of helicity angles as discussed in the text. Fig3.pdf [28 KiB] HiDef png [34 KiB] Thumbnail [7 KiB] *.C file Efficiency corrected $m_{ K^- \pi^+ }$ distribution for $B^0_s$ shown in squares (red) and $\overline{ B}{} ^0$ shown in circles (black) using $sW\!eights$ computed from the maximum likelihood fit to the ${ J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} K^- \pi^+$ invariant mass spectrum. Fig4.pdf [16 KiB] HiDef png [137 KiB] Thumbnail [52 KiB] *.C file Fitted signal distributions compared with the weighted angular distributions with $B^0_s$ $sW\!eights$ . Points with error bars show the data. The projection of the fit result is represented by the solid black line, and the contributions from the different amplitude components are described in the legend. Fig5.pdf [26 KiB] HiDef png [284 KiB] Thumbnail [95 KiB] *.C file Limits on the penguin parameters $a_i$ and $\theta_i$ obtained from intersecting contours derived from the ${C\!P}$ asymmetries and branching fraction information in $B^0_s\to { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} \overline{ K}{} ^{*0}$. Superimposed are the confidence level contours obtained from a $\chi^2$ fit to the data. Shown are the longitudinal (top), parallel (middle) and perpendicular (bottom) polarisation. Fig6a.pdf [215 KiB] HiDef png [839 KiB] Thumbnail [134 KiB] *.C file Fig6b.pdf [265 KiB] HiDef png [871 KiB] Thumbnail [150 KiB] *.C file Fig6c.pdf [250 KiB] HiDef png [706 KiB] Thumbnail [134 KiB] *.C file Dependence of the uncertainty on the penguin shift $\Delta\phi_{s,i}^{ { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} \phi}$ on the uncertainty on $\xi$. The bands correspond to the 68% C.L. The longitudinal (top), parallel (middle) and perpendicular (bottom) polarisations are shown. Fig7a.pdf [99 KiB] HiDef png [145 KiB] Thumbnail [46 KiB] *.C file Fig7b.pdf [99 KiB] HiDef png [140 KiB] Thumbnail [45 KiB] *.C file Fig7c.pdf [99 KiB] HiDef png [132 KiB] Thumbnail [45 KiB] *.C file Limits on the penguin parameters $a_i$ and $\theta_i$ obtained from intersecting contours derived from the ${C\!P}$ asymmetries and branching fraction information in $B^0_s\to { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} \overline{ K}{} ^{*0}$ and $B^0 \to { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} \rho^0$. Superimposed are the confidence level contours obtained from a $\chi^2$ fit to the data. The longitudinal (top), parallel (middle) and perpendicular (bottom) polarisations are shown. Fig8a.pdf [189 KiB] HiDef png [1 MiB] Thumbnail [181 KiB] *.C file Fig8b.pdf [249 KiB] HiDef png [1 MiB] Thumbnail [175 KiB] *.C file Fig8c.pdf [217 KiB] HiDef png [1 MiB] Thumbnail [188 KiB] *.C file Animated gif made out of all figures. PAPER-2015-034.gif Thumbnail

## Tables and captions

 Expected yields of each background component in the signal mass range. Table_1.pdf [52 KiB] HiDef png [94 KiB] Thumbnail [16 KiB] tex code The $C_{\rm SP}$, $C_{\rm SD}$ and $C_{\rm PD}$ factors calculated in each of the four $m_{ K^- \pi^+ }$ bins around the $\overline{ K}{} ^{*0}$ peak. Table_2.pdf [58 KiB] HiDef png [55 KiB] Thumbnail [9 KiB] tex code Summary of the measured $B^0_s\to { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} \overline{ K}{} ^{*0}$ {\rm P--wave} properties and their statistical and systematic uncertainties. When no value is given, it means an uncertainty below $5\times10^{-4}$, except for the two phases, $\delta_\parallel$ (rad) and $\delta_\perp$ (rad), in which case the uncertainty is below $5\times10^{-3}$. Table_3.pdf [67 KiB] HiDef png [171 KiB] Thumbnail [24 KiB] tex code Summary of the measured $B^0_s\to { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} \overline{ K}{} ^{*0}$ {\rm S--wave} properties and their statistical and systematic uncertainties. When no value is given, it means an uncertainty below $5\times10^{-4}$, except for the four phases related to the {\rm S--wave} component, $\delta_{\rm S}$ (rad), in which case the uncertainty is below $5\times10^{-3}$. The $m_{ K^- \pi^+ }$ binning definition is identical to the one given in Table ???. Table_4.pdf [81 KiB] HiDef png [166 KiB] Thumbnail [24 KiB] tex code Summary of the measured values for the relative branching fractions and their statistical and systematic uncertainties. Table_5.pdf [100 KiB] HiDef png [86 KiB] Thumbnail [14 KiB] tex code Corrected angular acceptance weights for $K^-\pi^+$ events lying in the first $m_{ K^- \pi^+ }$ bin. The $\xi_{ij}$ weights are normalised with respect to the $\xi_{00}$ weight. Table_6.pdf [41 KiB] HiDef png [233 KiB] Thumbnail [31 KiB] tex code Statistical correlation matrix for the parameters from the angular fit. Table_7.pdf [48 KiB] HiDef png [328 KiB] Thumbnail [65 KiB] tex code

Created on 20 April 2019.Citation count from INSPIRE on 25 April 2019.