Reheating Bounds from Thermal GUT Monopole Production
Abstract
Magnetic monopoles are a generic prediction of Grand Unified Theories (GUTs) that are in tension with modern cosmological and observational bounds. In this paper, we calculate the present-day abundance of GUT monopoles produced thermally in the early Universe. We improve on previous calculations by accounting for full relativistic corrections to the thermal abundance and enhanced monopole annihilation due to the emission of radiation and scattering off massive gauge bosons, the Standard Model fermions and their superpartners. To obtain a present-day energy density less than that of dark matter, we show that the reheating temperature of the Universe, TRH, must be less than $0.55$ times the GUT symmetry breaking scale TGUT for the canonical 't Hooft-Polyakov monopole mass. Accounting for Parker bounds on the present-day magnetic monopole abundance, the bound is tightened to TRH/TGUT ≲ 0.45. Furthermore, experimental bounds from Super-Kamiokande require TRH/TGUT ≲ 0.35 in our scenario.
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BibTeX
@misc{liveoak2026reheating,
title = {{Reheating Bounds from Thermal GUT Monopole Production}},
author = {Donald Liveoak and Arielle Schutz and James D. Wells},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.18596},
eprint = {2609.18596},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.18596},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Reheating Bounds from Thermal GUT Monopole Production
AU - Donald Liveoak
AU - Arielle Schutz
AU - James D. Wells
PY - 2026
DA - 2026/09/16
PB - arXiv
DO - 10.48550/arxiv.2609.18596
UR - https://arxiv.org/abs/2609.18596
AB - Magnetic monopoles are a generic prediction of Grand Unified Theories (GUTs) that are in tension with modern cosmological and observational bounds. In this paper, we calculate the present-day abundance of GUT monopoles produced thermally in the early Universe. We improve on previous calculations by accounting for full relativistic corrections to the thermal abundance and enhanced monopole annihilation due to the emission of radiation and scattering off massive gauge bosons, the Standard Model fermions and their superpartners. To obtain a present-day energy density less than that of dark matter, we show that the reheating temperature of the Universe, T_RH, must be less than $0.55$ times the GUT symmetry breaking scale T_GUT for the canonical 't Hooft-Polyakov monopole mass. Accounting for Parker bounds on the present-day magnetic monopole abundance, the bound is tightened to T_RH/T_GUT ≲ 0.45. Furthermore, experimental bounds from Super-Kamiokande require T_RH/T_GUT ≲ 0.35 in our scenario.
ER -