We study the contribution to the QCD axion dark matter abundance that is produced by string defects during the so-called scaling regime. Clear evidence of scaling violations is found, the most conservative extrapolation of which strongly suggests a large number of axions from strings. In this regime, nonlinearities at around the QCD scale are shown to play an important role in determining the final abundance. The overall result is a lower bound on the QCD axion mass in the post-inflationary scenario that is substantially stronger than the naive one from misalignment.

More axions from strings / Gorghetto, Marco; Hardy, Edward; Villadoro, Giovanni. - In: SCIPOST PHYSICS. - ISSN 2542-4653. - 10:2(2021), pp. 1-59. [10.21468/scipostphys.10.2.050]

More axions from strings

Gorghetto, Marco;Villadoro, Giovanni
2021-01-01

Abstract

We study the contribution to the QCD axion dark matter abundance that is produced by string defects during the so-called scaling regime. Clear evidence of scaling violations is found, the most conservative extrapolation of which strongly suggests a large number of axions from strings. In this regime, nonlinearities at around the QCD scale are shown to play an important role in determining the final abundance. The overall result is a lower bound on the QCD axion mass in the post-inflationary scenario that is substantially stronger than the naive one from misalignment.
2021
10
2
1
59
050
https://doi.org/10.21468/SciPostPhys.10.2.050
https://arxiv.org/abs/2007.04990
Gorghetto, Marco; Hardy, Edward; Villadoro, Giovanni
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/20.500.11767/142175
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