Alladi Ramakrishnan Hall

Dark Neutrons: Cosmology, Astrophysics & Laboratory

Dr. Nirmal Raj

TRIUMPH, Canada

New states that mix with the neutron, such as dark baryons and mirror neutrons, have been proposed to address dark matter, baryogenesis, the long-standing neutron lifetime anomaly, and the recent (albeit later disfavoured) XENON1T excess. First I show that such states are extensively probed by cosmological epochs and astrophysical systems where protons, neutrons and electrons play a central role. In particular, wide-ranging constraints arise from (1) Big Bang nucleosynthesis, (2) cosmic microwave background spectra, (3) the stability of nuclides in low-metallicity stars, (4) a novel mechanism to heat neutron stars by tapping the energy stored in their Fermi seas. Then I show that even more sensitive to dark neutrons would be a new "neutrons-shining-through-a-wall" search at a deep-underground accelerator facility such as the imminent IsoDAR experiment, and a reinterpretation of neutron disappearance searches at ultra-cold neutron facilities.