1996/08/31 by Tom Banks, Michael Dine · 142 citations
Physics and Astronomy · #Astrophysics #Axion #Compactification (mathematics) #Cosmology #Cosmology and Gravitation Theories #Dark Matter and Cosmic Phenomena #Dark matter #Gravitino #Moduli #Non-critical string theory #Particle physics #Particle physics theoretical and experimental studies #Physics #Pure mathematics #Quantum gravity #Quantum mechanics #Relationship between string theory and quantum field theory #String (physics) #String cosmology #String theory #Supergravity #Supersymmetry #Theoretical physics #hep-ph #hep-th
paper · pdf · doi:10.1016/s0550-3213(97)00413-6
published in Nuclear Physics B 505(1-2), 445-460 (Elsevier BV) · 24 pages, uses harvmac. Refs corrected plus spelling
arxiv created 1996/09/04 · openalex publication_date 1997/11/01 · arxiv updated 2014/11/17 · openalex created_date 2020/11/23 · openalex updated_date 2026/08/06
String theory posesses numerous axion candidates. The recent realization that the compactification radius in string theory might be large means that these states can solve the strong CP problem. This still leaves the question of the cosmological bound on the axion mass. Here we explore two schemes for accommodating such light axions in cosmology. In the first, we note that in string theory the universe is likely to be dominated early on by the coherent oscillations of some moduli. The usual moduli problem assumes that these fields have masses comparable to the gravitino. We argue that string moduli are likely to be substantially more massive, eliminating this problem. In such cosmologies the axion bound is significantly weakened. Plausible mechanisms for generating the baryon number density are described. In the second, we point out that in string theory, the axion potentials might be much larger at early times than at present. In string theory, if CP violation is described by a small parameter, the axion may sit sufficiently close to its true minimum to invalidate the bounds.