New weakly-coupled forces hidden in low-energy QCD

Abstract

Is it possible to detect a new weakly-coupled force at the QCD scale that interacts primarily with quarks? This work investigates experimental signatures of a new MeV - GeV gauge boson that couples to baryon number, with attention to the 100 MeV - GeV mass range that is the regime of nonperturbative QCD. Such a state can be searched for in rare radiative decays of light mesons ($\eta, \eta^\prime, \phi, \omega$) as a $\pi^0 \gamma$ resonance, which is its leading decay mode from 140 - 620 MeV. This is a new discovery window for forces beyond the Standard Model that is not covered by existing dark photon searches.