Probing new physics with underground accelerators and radioactive sources

摘要

New light, weakly coupled particles can be efficiently produced at existing and future high-intensity accelerators and radioactive sources in deep underground laboratories. Once produced, these particles can scatter or decay in large neutrino detectors (e.g. Super-K and Borexino) housed in the same facilities. We discuss the production of weakly coupled scalars ? via nuclear de-excitation of an excited element into the ground state in two viable concrete reactions: the decay of the 0 + excited state of 16 O populated via a ( p , α ) reaction on fluorine and from radioactive 144 Ce decay where the scalar is produced in the de-excitation of 144 Nd ? , which occurs along the decay chain. Subsequent scattering on electrons, e ( ? , γ ) e , yields a mono-energetic signal that is observable in neutrino detectors. We show that this proposed experimental setup can cover new territory for masses 250 keV ≤ m ? ≤ 2 m e and couplings to protons and electrons, 10 ? 11 ≤ g e g p ≤ 10 ? 7 . This parameter space is motivated by explanations of the “proton charge radius puzzle”, thus this strategy adds a viable new physics component to the neutrino and nuclear astrophysics programs at underground facilities.