Semi-inclusive lepton flavor universality ratio in b → sl+ l- transitions

We construct a semi-inclusive lepton flavor universality (LFU) ratio, R-Sigma, to test mu/e universality in b -> sl(+)l(-) transitions at e(+)e(-) B-meson factories. Combining different decay channels, this observable maximizes the sensitivity to possible LFU violations of short-distance origin, yet preserves a clean theoretical interpretation in the case of a deviation from its Standard Model prediction, R-Sigma(SM) = 1.

Automated summary

A semi-inclusive lepton flavor universality (LFU) ratio, R-Sigma, is constructed to test mu/e universality in b -> sl(+)l(-) transitions at e(+)e(-) B-meson factories. By combining different decay channels, this observable maximizes sensitivity to possible violations of LFU from short-distance origin, while maintaining a clean theoretical interpretation in case of deviation from its Standard Model prediction, R-Sigma(SM) = 1.