Cosmological problems of the string axion alleviated by high scale SUSY of m3/2≃10-100 TeV

Masahiro Kawasaki, Tsutomu T. Yanagida, Norimi Yokozaki

Research output: Contribution to journalArticlepeer-review

2 Citations (Scopus)


The string axion may provide the most attractive solution to the strong CP problem in QCD. However, the axion energy density easily exceeds the dark matter density in the present universe due to a large decay constant around 1016 GeV, unless the initial value of the axion field is finely tuned. We show that this problem is alleviated if and only if the SUSY particle mass scale is 10-100 TeV, since the decay of the saxion can produce a large enough amount of entropy after the QCD phase transition, not disturbing the BBN prediction. The saxion decay also produces a large number of the lightest SUSY particles (LSPs). As a consequence, R-parity needs to be violated to avoid the overproduction of the LSPs. The saxion field can be stabilized with relatively simple Kähler potentials, not inducing a too large axion dark radiation. Despite the large entropy production, the observed baryon number is explained by the Affleck-Dine mechanism. Furthermore, the constraint from isocurvature perturbations is relaxed, and the Hubble constant during inflation can be as large as several ×1010 GeV.

Original languageEnglish
Pages (from-to)389-394
Number of pages6
JournalPhysics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics
Publication statusPublished - 2016 Feb 10
Externally publishedYes

ASJC Scopus subject areas

  • Nuclear and High Energy Physics


Dive into the research topics of 'Cosmological problems of the string axion alleviated by high scale SUSY of m3/2≃10-100 TeV'. Together they form a unique fingerprint.

Cite this