A Cosmological Lithium Solution from Discrete Gauged Baryon Minus Lepton Number

Abstract

We propose the infrared gauge symmetry of our sector includes an unbroken discrete gauged subgroup of baryon minus lepton number of order 2 × 3 colors × 3 generations. We UV complete this at a scale Λ as the familiar U (1) B−NcL Abelian Higgs theory, and the early universe phase transition forms cosmic strings which are charged under an emergent higher-form generalized symmetry. These topological defects catalyze interactions which turn 3 baryons into 3 leptons at strong scale rates in an analogue of the Callan-Rubakov effect.The cosmological lithium problem-that the observed primordial abundance is lower than theoretical expectations by a factor of a few-is perhaps the most statistically significant anomaly of SM + ΛCDM, and has resisted decades of attempts by cosmologists, nuclear physicists, and astronomers alike to root out systematics. We write down a model in which B − N c L strings superconduct bosonic global baryon plus lepton number currents and catalyze solely 3p + → 3e + . We suggest that such cosmic strings have disintegrated O(1) of the lithium nuclei formed during Big Bang Nucleosynthesis and estimate the rate, with our benchmark model finding Λ ∼ 10 8 GeV gives the right number density of strings. Figure 0: Photo of a commissioned abstract artist's impression in acrylic on canvas by Bailey Lingen, a Chicago-based artist and trans rights activist who produces music under the name LiTHiUM THiEF.