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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_00016v1 (pdf) |
| Date submitted: | 2022-10-03 11:58 |
| 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 find that many such models predict unacceptable isocurvature perturbations. We will discuss conditions which should be fulfilled by ALP models with U(1) unbroken during inflation to be phenomenologically interesting.
Current status:
Reports on this Submission
Report #1 by Anonymous (Referee 3) on 2022-11-10 (Invited Report)
- Cite as: Anonymous, Report on arXiv:scipost_202210_00016v1, delivered 2022-11-10, doi: 10.21468/SciPost.Report.6117
Strengths
1. This work studies the feeble-$\lambda$ case of the PQ potential, and argues that here the curvature corrections can be crucial. Especially, in the quasi ``SUSY'' limit, a second (global) VEV may appear, leading to suppressed isocurvature perturbations.
2. The topic of this manuscript is well motivated. And the idea to suppress stochastic fluctuations by achieving an earlier second (global) VEV from curvature effect is very interesting.
Weaknesses
1. The statement in Section.3 is a little confusing for me. Does $S$ 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.
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?
3. The temperature correction is always neglected, while potentially it may lead to interesting effects.
Report
This submission definitely meets the criteria of SciPost Physics Proceedings, and it should be published here after several minor improvements are made.
Requested changes
1. See the weakness 1 above.
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.
3. "in order to obtain bounded from below $V_{CW}$" sounds confusing, probably change it to "to make sure $V_{CW}$ is bounded from below" or so?