Freezing-in gravitational waves

Journal Article · Wed Jan 31 00:00:00 EST 2024 · Physical Review. D.

DOI:https://doi.org/10.1103/PhysRevD.109.023538· OSTI ID:2283474

Ghiglieri, Jacopo; Schütte-Engel, Jan; Speranza, Enrico

The thermal plasma in the early Universe produced a stochastic gravitational wave (GW) background, which peaks today in the microwave regime and was dubbed the cosmic gravitational microwave background (CGMB). In previous works, only single graviton production processes that contribute to the CGMB have been considered. Here, we also investigate graviton pair production processes and show that these can lead to a significant contribution if the ratio between the maximum temperature and the Planck mass, $T_{\max }/m_{\mathrm{p}}$ , divided by the internal coupling in the heat bath is large enough. As the dark matter freeze-in production mechanism is conceptually very similar to the GW production mechanism from the primordial thermal plasma, we refer to the latter as “GW freeze-in production.” We show that quantum gravity effects appear in single graviton production and are smaller by a factor $(T_{\max }/m_{\mathrm{p}}{)}^2$ than the leading order contribution. In our work, we explicitly compute the CGMB spectrum within a scalar model with quartic interaction.

Published by the American Physical Society 2024

• Research Organization: Univ. of Illinois at Urbana-Champaign, IL (United States)
• Sponsoring Organization: USDOE; USDOE Office of Science (SC)
• Grant/Contract Number: SC0015655
• OSTI ID: 2283474
• Alternate ID(s): OSTI ID: 2579338
• Journal Information: Physical Review. D., Journal Name: Physical Review. D. Journal Issue: 2 Vol. 109; ISSN PRVDAQ; ISSN 2470-0010
• Publisher: American Physical Society
• Country of Publication: United States
• Language: English

Related Subjects

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