Three exceptions in the calculation of relic abundances

Journal Article · Wed May 15 00:00:00 EDT 1991 · Physical Review, D (Particles Fields); (USA)

DOI:https://doi.org/10.1103/PhysRevD.43.3191· OSTI ID:5666538

Griest, K ^[1]; Seckel, D ^[2]

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1. Center for Particle Astrophysics and Astronomy Department, University of California, Berkeley, California 94720 (USA)
2. Bartol Research Institute, University of Delaware, Newark, Delaware 19716 (USA)

The calculation of relic abundances of elementary particles by following their annihilation and freeze-out in the early Universe has become an important and standard tool in discussing particle dark-matter candidates. We find three situations, all occurring in the literature, in which the standard methods of calculating relic abundances fail. The first situation occurs when another particle lies near in mass to the relic particle and shares a quantum number with it. An example is a light squark with neutralino dark matter. The additional particle must be included in the reaction network, since its annihilation can control the relic abundance. The second situation occurs when the relic particle lies near a mass threshold. Previously, annihilation into particles heavier than the relic particle was considered kinematically forbidden, but we show that if the mass difference is {similar to}5--15 %, these forbidden'' channels can dominate the cross section and determine the relic abundance. The third situation occurs when the annihilation takes place near a pole in the cross section. Proper treatment of the thermal averaging and the annihilation after freeze-out shows that the dip in relic abundance caused by a pole is not nearly as sharp or deep as previously thought.

• DOE Contract Number: AC02-78ER05007
• OSTI ID: 5666538
• Journal Information: Physical Review, D (Particles Fields); (USA), Vol. 43:10; ISSN 0556-2821
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
RELICT RADIATION
ABUNDANCE
UNIVERSE
NONLUMINOUS MATTER
ANNIHILATION
BOLTZMANN EQUATION
CROSS SECTIONS
HIGGS BOSONS
MASS DIFFERENCE
QUANTUM NUMBERS
QUARKS
SUPERSYMMETRY
W MINUS BOSONS
W PLUS BOSONS
Z NEUTRAL BOSONS
BASIC INTERACTIONS
BOSONS
DIFFERENTIAL EQUATIONS
ELECTROMAGNETIC INTERACTIONS
ELECTROMAGNETIC RADIATION
ELEMENTARY PARTICLES
EQUATIONS
FERMIONS
INTERACTIONS
INTERMEDIATE BOSONS
INTERMEDIATE VECTOR BOSONS
MATTER
MICROWAVE RADIATION
PARTIAL DIFFERENTIAL EQUATIONS
PARTICLE INTERACTIONS
PARTICLE PROPERTIES
POSTULATED PARTICLES
RADIATIONS
SYMMETRY
640106* - Astrophysics & Cosmology- Cosmology