Surveys of diffuse γ-ray in the interstellar medium (ISM) can be used to probe hydrogen-antihydrogen oscillations, by detecting the γ-ray emission from antihydrogen annihilation. A bound on the oscillation parameter δ was originally derived by Feinberg, Goldhaber and Steigman (1978). In this paper, we re-visit the original derivation by performing a more detailed analysis that (1) incorporates suppression effects from additional elastic and inelastic processes, (2) treats the ISM as a multi-phase medium, and (3) utilises more recent γ-ray data from the Fermi Large Area Telescope. We find that suppression from elastic scattering plays a more important role than previously thought, while the multi-phase nature of the ISM affects how the γ-ray data should be utilised. We derive a more accurate bound on the oscillation period that is about an order of magnitude weaker than the older bound.
Cite
@article{arxiv.1806.08233,
title = {Re-visiting the bounds on hydrogen-antihydrogen oscillations from diffuse $\gamma$-ray surveys},
author = {Yuval Grossman and Wee Hao Ng and Shamayita Ray},
journal= {arXiv preprint arXiv:1806.08233},
year = {2018}
}