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

Information

LHCb-PAPER-2015-034
CERN-PH-EP-2015-224
arXiv:1509.00400 [PDF]

(Submitted on 01 Sep 2015)
JHEP 11 (2015) 082
Inspire 1391324

Tools

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 [103 KiB] Thumbnail [82 KiB] *.C file
	Fig1b.pdf [8 KiB] HiDef png [114 KiB] Thumbnail [90 KiB] *.C file
	Fig1c.pdf [9 KiB] HiDef png [105 KiB] Thumbnail [85 KiB] *.C file
	Fig1d.pdf [11 KiB] HiDef png [116 KiB] Thumbnail [92 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 [285 KiB] Thumbnail [232 KiB] *.C file
Representation of helicity angles as discussed in the text.	Fig3.pdf [28 KiB] HiDef png [27 KiB] Thumbnail [15 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 [139 KiB] Thumbnail [127 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 [243 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 [772 KiB] Thumbnail [384 KiB] *.C file
	Fig6b.pdf [265 KiB] HiDef png [823 KiB] Thumbnail [431 KiB] *.C file
	Fig6c.pdf [250 KiB] HiDef png [631 KiB] Thumbnail [353 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 [144 KiB] Thumbnail [103 KiB] *.C file
	Fig7b.pdf [99 KiB] HiDef png [140 KiB] Thumbnail [100 KiB] *.C file
	Fig7c.pdf [99 KiB] HiDef png [133 KiB] Thumbnail [100 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 [486 KiB] *.C file
	Fig8b.pdf [249 KiB] HiDef png [957 KiB] Thumbnail [474 KiB] *.C file
	Fig8c.pdf [217 KiB] HiDef png [1 MiB] Thumbnail [499 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 [79 KiB] Thumbnail [39 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 [49 KiB] Thumbnail [22 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 [142 KiB] Thumbnail [59 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 [139 KiB] Thumbnail [58 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 [72 KiB] Thumbnail [34 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 [193 KiB] Thumbnail [80 KiB] tex code
Statistical correlation matrix for the parameters from the angular fit.	Table_7.pdf [48 KiB] Thumbnail [116 KiB] tex code