Baryon asymmetry of the Universe is one of the most intriguing open questions in modern particle physics: the observable Universe is composed almost entirely of matter, with no evidence of primordial antimatter domains on cosmological scales. This matter–antimatter asymmetry must have been generated dynamically through physical processes in the early history of the cosmos, requiring the existence of baryon-number-violating processes.
Baryon number is an accidental global symmetry of the Standard Model (SM) at the classical level. Grand Unified Theories (GUTs)—a family of well-motivated SM extensions that unify the strong, weak, and electromagnetic interactions into a single gauge group at high energy scales—naturally predict baryon number violation. GUTs predict nucleon decay as an extremely rare process, with lifetimes far exceeding the age of the Universe ($\sim 1.38 \times 10^{10}$ years). Consequently, massive underground detectors employing state-of-the-art technologies are critical for these searches: deep underground locations shield against cosmic-ray muon backgrounds, while advanced reconstruction techniques enable the rejection of atmospheric neutrino interactions that could mimic the expected signal.
In this presentation, we discuss how the DUNE Far Detector, based on liquid argon time projection chamber technology, will contribute to this search. In particular, we focus on nucleon decay channels featuring a $K^+$ meson in the final state, such as $p \to \bar{\nu} K^+$.