부산대학교 도서관

We propose novel methods to determine the $\Upsilon(4S)\to B^+B^-$ and $\Upsilon(4S)\to B^0\bar B^0$ decay rates. The precision to which they and their ratio are known yields at present a limiting uncertainty around $2\%$ in measurements of absolute $B$ decay rates, and thus in a variety of applications, such as precision determinations of elements of the Cabibbo-Kobayashi-Maskawa matrix and flavor symmetry relations. The new methods we propose are based in one case on exploiting the $\Upsilon(5S)$ data sets, in the other case on the different average number of charged tracks in $B^\pm$ and $B^0$ decays. We estimate future sensitivities using these methods and discuss possible measurements of $f_d / f_u$ at the (HL-)LHC.
Comment: 10 pages, 3 figures