Amplitude analysis of the $B_{(s)}\to K^{\ast 0}{\overline{K}}^{\ast 0}$ decays and measurement of the branching fraction of the $B\to K^{\ast 0}{\overline{K}}^{\ast 0}$ decay

Abstract

The $B^0\to K^{\ast 0}{\overline{K}}^{\ast 0}$ and $B_s^0\to K^{\ast 0}{\overline{K}}^{\ast 0}$ decays are studied using proton-proton collision data corresponding to an integrated luminosity of 3fb${}^{-1}$. An untagged and time-integrated amplitude analysis of $B_{(s)}^0\to (K^{+}\ddot{I}{€}^{-})(K^{-}\ddot{I}{€}^{+})$ decays in two-body invariant mass regions of 150 MeV$/c^2$ around the $K^{\ast 0}$ mass is performed. A stronger longitudinal polarisation fraction in the $B^0\to K^{\ast 0}{\overline{K}}^{\ast 0}$ decay, $f_L=0.724\pm 0.051(\mathrm{stat})\pm 0.016(\mathrm{syst})$, is observed as compared to $f_L=0.240\pm 0.031(\mathrm{stat})\pm 0.025(\mathrm{syst})$ in the $B_s^0\to K^{\ast 0}{\overline{K}}^{\ast 0}$ decay. The ratio of branching fractions of the two decays is measured and used to determine $\mathcal{B}(B^0\to K^{\ast 0}{\overline{K}}^{\ast 0})=(8.0\pm 0.9(\mathrm{stat})\pm 0.4(\mathrm{syst}))\times 10^{-7}$.

All figures and tables, along with any supplementary material and additional information, are available at https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2019-004.html (LHCb public pages)