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Axion-like particle as Cold Dark Matter via the misalignment mechanism with PQ symmetry unbroken during inflation
by P. Kozow, M. Olechowski
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Submission summary
| Authors (as registered SciPost users): | Pawel Kozow |
| Submission information | |
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| Preprint Link: | scipost_202210_00016v2 (pdf) |
| Date submitted: | 2022-11-19 11:54 |
| Submitted by: | Kozow, Pawel |
| Submitted to: | SciPost Physics Proceedings |
| Proceedings issue: | 14th International Conference on Identification of Dark Matter (IDM2022) |
| Ontological classification | |
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| Academic field: | Physics |
| Specialties: |
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Abstract
The QCD axion and axion-like particles (ALPs) are well motivated candidates for Cold Dark Matter (CDM). Such models may be divided into two classes depending on whether the associated Peccei-Quinn (PQ) symmetry is broken or not during inflation. The latter case is usually considered to be quite simple with relic density depending only on the corresponding decay constant and with no constraints from the known bounds on isocurvature perturbations. We will show that the situation is much more complicated. We will discuss conditions which should be fulfilled by ALP models with U(1) unbroken during inflation to be phenomenologically interesting.
Author comments upon resubmission
for further improving the presentation. We have addressed all of the referee's points, in particular by making
modifications to the text, which are marked as red in the new version (2nd). A description of the modifications together with answers to the Referee's questions or comments, are listed below.
List of changes
"1. The statement in Section.3 is a little confusing for me. Does SS obtain a non-zero VEV during the inflation, or after the inflation? If this new proposal is more like a “PQ broken'' instead of “PQ unbroken'' scenario, the author may mention it explicitly."
S obtains VEV during inflation.
- Concerning the first issue, the text was further improved by modifying the sentence which contains eq. (6) and the former, on page 4.
- An extra comment on the second issue was added at the end of the current verion. It starts at the very end of the main text on page 4.
"2. If I understand it correctly, the first equality in Eq. (6) is only true during the inflation, since the curvature effects become time-dependent in the post-inflationary era, right?"
The first equality in Eq. (6) is for the post-inflationary era. It already accounts for the fact that the curvature effects to the potential become time-dependent after inflation. Ihe improvements to the text above eq. (6) described above already address clarification of this issue.
"3. The temperature correction is always neglected, while potentially it may lead to interesting effects."
- A corresponding comment was added in the footnote on page 4.
"2. The abstract mentions that "We find that many such models predict unacceptable isocurvature perturbations", but this is not explicitly discussed in the main text. I suggest the author remove or improve this sentence."
- We followed the Referee's suggestion and removed this sentence.
"3. "in order to obtain bounded from below VCW sounds confusing, probably change it to "to make sure VCWVCW is bounded from below" or so?"
- The sentence above eq. (3) was modified accordingly.
Current status:
Reports on this Submission
Report #1 by Anonymous (Referee 2) on 2022-11-22 (Invited Report)
- Cite as: Anonymous, Report on arXiv:scipost_202210_00016v2, delivered 2022-11-22, doi: 10.21468/SciPost.Report.6174
Report
The authors have answered the questions in the previous report. I really appreciate the texts added to the end of Sec.3, and would happily recommend the publication of this manuscript in SciPost Physics Proceedings, just after the very naive question below.
I still hope to understand Eq. (6) better. In a (post-inflationary) radiation-dominated Universe, the curvature correction should be a function of temperature $T$, being independent of inflation Hubble parameter $H_I$. So, could the authors explain explicitly why $H_I$ appears in the first equality of Eq. (6), but $T$ does not. Is $H_I$ simply from $S_i$, and $T$-terms are negligible, or I am missing something?
BTW, at the end of footnote 1, it should be "the scope of this work".