First Exclusive Reconstruction of the $B^{*+},\ B^{*0},\ \text{and}\ B_s^{*0}$ Mesons and Precise Measurement of Their Masses

Using proton-proton collision data collected by the CMS experiment at s = 13 TeV in 2016–2018, corresponding to an integrated luminosity of 140 fb − 1 , the first full reconstruction of the three vector B meson states, B * + , B * 0 , and B s * 0 , is performed. The mass differences between the excited mesons and their corresponding ground states are measured to be m ( B * + ) − m ( B + ) = 45.277 ± 0.039 ± 0.027 MeV , m ( B * 0 ) − m ( B 0 ) = 45.471 ± 0.056 ± 0.028 MeV , and m ( B s * 0 ) − m ( B s 0 ) = 49.407 ± 0.132 ± 0.041 MeV , where the first uncertainties are statistical and the second are systematic. These results improve on the precision of previous measurements by an order of magnitude.