The QCD Axion and Moduli Stabilisation
ArXiv hep-th/0602233 (2006)
Abstract:
We investigate the conditions for a QCD axion to coexist with stabilised
moduli in string compactifications. We show how the simplest approaches to
moduli stabilisation give unacceptably large masses to the axions. We observe
that solving the F-term equations is insufficient for realistic moduli
stabilisation and give a no-go theorem on supersymmetric moduli stabilisation
with unfixed axions applicable to all string compactifications and relevant to
much current work. We demonstrate how nonsupersymmetric moduli stabilisation
with unfixed axions can be realised. We finally outline how to stabilise the
moduli such that f_a is within the allowed window 10^9 GeV < f_a < 10^{12} GeV,
with f_a ~ \sqrt{M_{SUSY} M_P}.
