On dark radiation from string moduli decay to ALPs
We examine the issue of dark radiation (DR) from string moduli decay into axion-like particles (ALPs). In KKLT-type models of moduli stabilization, the axionlike phases of moduli fields are expected to decouple whilst in LVS-type moduli stabilization some can remain light and may constitute dark radiation. Here, we evaluate modulus decay to Minimal Supersymmetric Standard Model (MSSM) particles and dark radiation for more general compactifications. In spite of tightening error bars on ΔNeff, we find only mild constraints on modulus-ALP couplings due to the somewhat suppressed modulus branching fraction to DR owing to the large number of MSSM decay modes. We anticipate that future CMB experiments with greater precision on ΔNeff may still turn up evidence for DR if the ALP associated with the lightest modulus field is indeed light.
- Research Organization:
- Univ. of Oklahoma, Norman, OK (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), High Energy Physics (HEP)
- Grant/Contract Number:
- SC-0017647; SC-0009956; SC0009956; SC0017647
- OSTI ID:
- 2335540
- Alternate ID(s):
- OSTI ID: 1863842; OSTI ID: 1865336
- Journal Information:
- Journal of High Energy Astrophysics, Journal Name: Journal of High Energy Astrophysics Vol. 34 Journal Issue: C; ISSN 2214-4048
- Publisher:
- ElsevierCopyright Statement
- Country of Publication:
- Netherlands
- Language:
- English
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