Thermal relics in modified cosmologies: Bounds on evolution histories of the early Universe and cosmological boosts for PAMELA

Journal Article · Tue Jun 15 04:00:00 EDT 2010 · Physical Review. D, Particles Fields

DOI:https://doi.org/10.1103/PHYSREVD.81.123522· OSTI ID:21408055

Catena, R ^[1]; Fornengo, N ^[2]; Pato, M ^[3]; Pieri, L ^[4]; Masiero, A ^[3]

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1. Institut fuer Theoretische Physik, Philosophenweg 16, D-69120, Heidelberg (Germany)
2. Dipartimento di Fisica Teorica, Universita di Torino, via P. Giuria 1, I-10125 Torino (Italy)
3. Dipartimento di Fisica, Universita di Padova, via Marzolo 8, I-35131, Padova (Italy)
4. Dipartimento di Astronomia, Universita di Padova, vicolo dell'Osservatorio 3, I-35122, Padova (Italy)

Alternative cosmologies, based on extensions of general relativity, predict modified thermal histories in the early Universe during the pre-big bang nucleosynthesis era, an epoch which is not directly constrained by cosmological observations. When the expansion rate is enhanced with respect to the standard case, thermal relics typically decouple with larger relic abundances. The correct value of the relic abundance is therefore obtained for larger annihilation cross sections, as compared to standard cosmology. A direct consequence is that indirect detection rates are enhanced. Extending previous analyses of ours, we derive updated astrophysical bounds on the dark matter annihilation cross sections and use them to constrain alternative cosmologies in the pre-big bang nucleosynthesis era. We also determine the characteristics of these alternative cosmologies in order to provide the correct value of relic abundance for a thermal relic for the (large) annihilation cross section required to explain the PAMELA results on the positron fraction, therefore providing a ''cosmological boost'' solution to the dark matter interpretation of the PAMELA data.

• OSTI ID: 21408055
• Journal Information: Physical Review. D, Particles Fields, Journal Name: Physical Review. D, Particles Fields Journal Issue: 12 Vol. 81; ISSN PRVDAQ; ISSN 0556-2821
• Country of Publication: United States
• Language: English

Related Subjects

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
79 ASTRONOMY AND ASTROPHYSICS
ANNIHILATION
ASTROPHYSICS
COSMOLOGY
CROSS SECTIONS
DETECTION
EVOLUTION
EXPANSION
FIELD THEORIES
GENERAL RELATIVITY THEORY
INTERACTIONS
MATHEMATICAL SOLUTIONS
MATTER
NONLUMINOUS MATTER
NUCLEOSYNTHESIS
PARTICLE INTERACTIONS
PHYSICS
RELATIVITY THEORY
SYNTHESIS
UNIVERSE