On the origin of dark matter axions

✍ Scribed by E.P.S Shellard; R.A Battye

• Publisher: Elsevier Science
• Year: 1999
• Tongue: English
• Weight: 30 KB
• Volume: 72
• Category: Article
• ISSN: 0920-5632
• DOI: 10.1016/s0920-5632(98)00507-6

✦ Synopsis

We discuss the possible sources of dark matter axions in the early universe. In the standard thermal scenario, an axion string network forms at the Peccei-Quinn phase transition T~fa and then radiatively decays into a cosmological background of axions; to be the dark matter, these axions must have a mass m a ~ 100 ~teW with specified large uncertainties. An inflationary phase with a reheat temperature below the PQ-scale Treh ~< fo can also produce axion strings through quantum fluctuations, provided that the Hubble parameter during inflation is large H1 >fa; this case again implies a dark matter axion mass ma ~ 100 ~teV. For a smaller Hubble parameter during inflation HI <f~, 'anthropic tuning' allows dark matter axions to have any mass in a huge range below m a < 1 meV.