Neutron-antineutron oscillations and |ΔB|=2 deuteron decay in chiral EFT

Baryon-number (B) violation is an essential ingredient for explaining the observed matter-antimatter asymmetry in the universe. An interesting class of beyond-the-standard-model models explaining the matter-antimatter asymmetry violates B by two units. In such models neutrons can oscillate into antineutrons and otherwise stable nuclei can decay. In this talk I will present a description for neutron-antineutron (n-nbar) oscillations and |ΔB| = 2 deuteron decay in chiral effective field theory (χEFT), which is a low-energy EFT of QCD. I will start with the one-(anti)nucleon sector and give our result for the n-nbar oscillation time. Then I will move on to the two-(anti)nucleon sector. Power-counting and naive dimensional analysis arguments imply that for most |ΔB| = 2 sources n-nbar oscillation is the dominant |∆B| = 2 mechanism for deuteron decay. We find that for these sources the limit on the deuteron lifetime puts a more stringent limit on the n-nbar oscillation time than previously thought. For one source we expect the relation between the deuteron decay rate and the n-nbar oscillation time to be very different, which may allow for a (partial) identification the |ΔB| = 2 source at the quark level from combined data of deuteron decay and free n-nbar oscillations.