Candidate theories to explain the anomalous spectroscopic signatures of atomic H in molecular H$_2$ crystals

TL;DR

This paper reviews and critically evaluates various theories explaining anomalous spectroscopic signatures of atomic hydrogen in solid molecular hydrogen, including the potential role of Bose-Einstein condensation, and suggests future experimental directions.

Contribution

It provides a comprehensive analysis of existing hypotheses for the anomalies and assesses their validity, offering predictions for future experimental tests.

Findings

Certain theories can explain some experimental features

Bose-Einstein condensation remains a plausible explanation

Guidelines for future experiments are proposed

Abstract

We analyze a number of proposed explanations for spectroscopic anomalies observed in atomic hydrogen defects embedded in a solid molecular hydrogen matrix. In particular, we critically evaluate the possibility that these anomalies are related to Bose-Einstein condensation (both global and local). For each proposed mechanism we discuss which aspects of the experiment can be explained, and make predictions for future experiments.