Echoes of Nucleon Decay from Long-Lived Particles

TL;DR

This paper introduces a novel class of nucleon decay observables involving long-lived particles that produce spatially separated but correlated decay signatures, enhancing detection prospects in large neutrino detectors.

Contribution

It proposes a new experimental signature for baryon number violation involving long-lived particles and demonstrates the potential sensitivity of current and future detectors.

Findings

Super-Kamiokande, Hyper-Kamiokande, and JUNO can achieve up to 80% acceptance for these signatures.

Echo signatures are applicable to any visibly decaying long-lived particle.

The study constructs effective operators and models for vector LLPs.

Abstract

Nucleon decay searches provide uniquely sensitive probes of baryon number violation and physics beyond the Standard Model. We propose a new class of nucleon decay observables involving long-lived particles (LLPs), characterized by spatially separated but temporally correlated "echo" vertices not captured by conventional prompt searches. Focusing on vector LLPs, we construct effective operators and ultraviolet realizations, and show that Super-Kamiokande, Hyper-Kamiokande and JUNO can achieve geometric acceptances approaching 80% over a broad range of LLP decay lengths. Echo signatures could in principle arise from any visibly decaying LLP.