Hints of new physics in bottomonium decays and spectroscopy

Abstract

A non-standard light CP-odd Higgs boson could induce a slight (but observable) lepton universality breakdown in Upsilon leptonic decays. Moreover, the mixing between such a pseudoscalar Higgs and $η_b$ states might shift the mass levels of the latter, thereby changing the values of the $m_{Υ(nS)}-m_{η_b(nS)}$ splittings predicted in the standard model. Besides, also the $η_b$ width could be broader than expected, with potentially negative consequences for its discovery in both $e^+e^-$ and hadron colliders.