Search for an invisible $Z^{\prime }$ in a final state with two muons and missing energy at Belle II

Belle II Collaboration, I. Adachi, K. Adamczyk +385

The $L_{\mu }-L_{\tau }$ extension of the standard model predicts the existence of a lepton-flavor-universality-violating $Z^{\prime }$ boson that couples only to the heavier lepton families.…