Abstract
We consider a model with a small explicit breaking of a global symmetry, as suggested by gravitational arguments. Our model has one scalar field transforming under a nonanomalous U(1) symmetry, and coupled to matter and to gauge bosons. The spontaneous breaking of the explicitly broken symmetry gives rise to a massive pseudo-Goldstone boson. We analyze thermal and nonthermal production of this particle in the early universe, and perform a systematic study of astrophysical and cosmological constraints on its properties. We find that for very suppressed explicit breaking the pseudo-Goldstone boson is a cold dark matter candidate.
Original language | English |
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Article number | 115009 |
Journal | Physical Review D - Particles, Fields, Gravitation and Cosmology |
Volume | 70 |
Issue number | 11 |
DOIs | |
Publication status | Published - 1 Dec 2004 |