Implications of an Improved Neutron-Antineutron Oscillation Search for Baryogenesis: A Minimal Effective Theory Analysis

Abstract

Future neutron-antineutron ($n$-$\bar{n}$) oscillation experiments, such as at the European Spallation Source and the Deep Underground Neutrino Experiment, aim to find first evidence of baryon number violation. We investigate implications of an improved $n$-$\bar{n}$ oscillation search for baryogenesis via interactions of $n$-$\bar{n}$ mediators, parameterized by an effective field theory (EFT). We find that even in a minimal EFT setup, there is overlap between the parameter space probed by $n$-$\bar{n}$ oscillation and the region that can realize the observed baryon asymmetry of the universe. The mass scales of exotic new particles are in the TeV-PeV regime, inaccessible at the LHC or its envisioned upgrades. Given the innumerable high energy theories that can match to, or resemble, the minimal EFT that we discuss, future $n$-$\bar{n}$ oscillation experiments could probe many viable theories of baryogenesis beyond the reach of other experiments.

Comments: 14 pages, 5 figures; v2: revised discussion on future ESS and DUNE sensitivity, added comment on dinucleon decays