Measurement of B$_s^0$ and B$^+$ meson yields in PbPb collisions at ${\sqrt{s_{\text{NN}}}} = 5.02$ TeV

The B$^{0}_s$ and B$^{+}$ production cross sections are measured in PbPb collisions at a center-of-mass energy per nucleon pair of $5.02\,$TeV. The data sample, collected by the CMS detector at the LHC, corresponds to an integrated luminosity of $1.7\,\text{nb}^{-1}$. The mesons are reconstructed in the exclusive decay channels B$^{0}_s\rightarrow{J}/\psi\,\phi(1020)$ and B$^{+}\rightarrow{J}/\psi\,K^{+}$. The B$^{0}_s$ meson is observed with a statistical significance in excess of 5 standard deviations for the first time in nucleus-nucleus collisions. The measurements are performed as a function of the transverse momentum of the B mesons, in the interval $7-50\,$GeV$/c$, and of the PbPb collision centrality. The ratio of production yields of {B}$^{0}_s$ and {B}$^{+}$ is also presented.