First Exclusive Reconstruction of the B^*+, B^*0, and B^*0ₛ 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^*0_𝑠, 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⁡ (𝐵⁰) =45. 471±0. 056±0. 028 MeV, and 𝑚⁡ (𝐵^*0_𝑠) −𝑚⁡ (𝐵⁰_𝑠) =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.