Exotic Particles at the DUNE Near Detector from Charged Pion Scattering

TL;DR

This paper explores how charged pion scattering in the DUNE Near Detector can produce exotic particles like millicharged particles and axion-like particles, enhancing detection sensitivity over previous methods.

Contribution

It introduces a new production mechanism via charged pion rescattering and demonstrates improved sensitivity of DUNE to these particles using chiral perturbation theory.

Findings

Charged pion rescattering can dominate exotic particle production.

DUNE's sensitivity to MCPs and ALPs is significantly improved.

Parameter space regimes where pion production is the main source.

Abstract

Fixed-target proton-beam experiments produce a multitude of charged pions that rescatter in the beam dump. These charged pion scattering events can be an additional irreducible source of exotic particles which couple to photons or hadrons. We analyze the sensitivity of the DUNE Near Detector complex to millicharged particles (MCPs) and heavy axion-like particles (ALPs) with low-energy couplings to gluons. Using the framework of chiral perturbation theory, we demonstrate regimes of parameter space where the charged pion production channel dominates over previously-considered production mechanisms for both MCPs and ALPs, thereby improving the sensitivity of DUNE to these new particles compared to previous studies.