Orateur
Description
In this talk, I present novel methods [Bernlochner:2023bad] 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 $B$ meson 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 method proposed here is based on exploiting the existing and future $\Upsilon(5S)$ data sets, as well as global event characteristics in $B^\pm$ and $B^0$ decays. Estimates of future sensitivities using these methods and possible measurements of $f_d / f_u$ at the (HL-)LHC are briefly discussed.
