In the framework of a baryon-number-violating effective Lagrangian, we calculate improved lower bounds on partial lifetimes for proton and bound neutron decays, including p→ℓ+ℓ′+ℓ′−, n→ν¯ℓ+ℓ′−, p→ℓ+νν¯, and n→ν¯ν¯ν, where ℓ and ℓ′ denote e or μ, with both ℓ=ℓ′ and ℓ≠ℓ′ cases. Our lower bounds are substantially stronger than the corresponding lower bounds from direct experimental searches. We also present lower bounds on (τ/B)p→ℓ+γ, (τ/B)n→ν¯γ, (τ/B)p→ℓ+γγ, and (τ/B)n→ν¯γγ. Our method relies on relating the rates for these decay modes to the rates for decay modes of the form p→ℓ+M and n→ν¯M, where M is a pseudoscalar or vector meson, and then using the experimental lower bounds on the partial lifetimes for these latter decays.

• Received 16 October 2019

DOI:https://doi.org/10.1103/PhysRevD.100.115025

Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. Funded by SCOAP³.

Published by the American Physical Society