Study of charmonium production in $b$-hadron decays and first evidence for the decay $B_s^0\to \varphi \varphi \varphi$

Abstract

Using decays to $\varphi$-meson pairs, the inclusive production of charmonium states in $b$-hadron decays is studied with $pp$ collision data corresponding to an integrated luminosity of $3.0f{b}^{-1}$, collected by the LHCb experiment at centre-of-mass energies of 7 and 8 TeV. Denoting by $B_C\equiv B(b\to CX)\times B(C\to \varphi \varphi )$ the inclusive branching fraction of a $b$ hadron to a charmonium state $C$ that decays into a pair of $\varphi$ mesons, ratios $R_{C2}^{C1}\equiv B_{C1}/B_{C2}$ are determined as $R_{{\eta }_c(1S)}^{{\chi }_{c0}}=0.147\pm 0.023\pm 0.011$, $R_{{\eta }_c(1S)}^{{\chi }_{c1}}=0.073\pm 0.016\pm 0.006$, $R_{{\eta }_c(1S)}^{{\chi }_{c2}}=0.081\pm 0.013\pm 0.005$, $R_{{\chi }_{c0}}^{{\chi }_{c1}}=0.50\pm 0.11\pm 0.01$, $R_{{\chi }_{c0}}^{{\chi }_{c2}}=0.56\pm 0.10\pm 0.01$ and $R_{{\eta }_c(1S)}^{{\eta }_c(2S)}=0.040\pm 0.011\pm 0.004$. Here and below the first uncertainties are statistical and the second systematic. Upper limits at $90\%$ confidence level for the inclusive production of $X(3872)$, $X(3915)$ and ${\chi }_{c2}(2P)$ states are obtained as $R_{{\chi }_{c1}}^{X(3872)}<0.34$, $R_{{\chi }_{c0}}^{X(3915)}<0.12$ and $R_{{\chi }_{c2}}^{{\chi }_{c2}(2P)}<0.16$. Differential cross-sections as a function of transverse momentum are measured for the ${\eta }_c(1S)$ and ${\chi }_c$ states. The branching fraction of the decay $B_s^0\to \varphi \varphi \varphi$ is measured for the first time, $B(B_s^0\to \varphi \varphi \varphi )=(2.15\pm 0.54\pm 0.28\pm 0.21_B)\times 10^{-6}$. Here the third uncertainty is due to the branching fraction of the decay $B_s^0\to \varphi \varphi$, which is used for normalization. No evidence for intermediate resonances is seen. A preferentially transverse $\varphi$ polarization is observed. The measurements allow the determination of the ratio of the branching fractions for the ${\eta }_c(1S)$ decays to $\varphi \varphi$ and $p\bar{p}$ as $B({\eta }_c(1S)\to \varphi \varphi )/B({\eta }_c(1S)\to p\bar{p})=1.79\pm 0.14\pm 0.32$.

All figures and tables, along with any supplementary material and additional information, are available at https://lhcbproject.web.cern.ch/lhcbproject/Publications/LHCbProjectPublic/LHCb-PAPER-2017-007.html . This version differs by minor editorial modifications corresponding to the EPJC publication. No changes in the content of the paper