Big bang nucleosynthesis with a stiff fluid

Journal Article · Fri Oct 15 00:00:00 EDT 2010 · Physical Review. D, Particles Fields

DOI:https://doi.org/10.1103/PHYSREVD.82.083501· OSTI ID:21467385

Dutta, Sourish; Scherrer, Robert J ^[1]

---

1. Department of Physics and Astronomy, Vanderbilt University, Nashville, Tennessee 37235 (United States)

Models that lead to a cosmological stiff fluid component, with a density {rho}{sub S} that scales as a{sup -6}, where a is the scale factor, have been proposed recently in a variety of contexts. We calculate numerically the effect of such a stiff fluid on the primordial element abundances. Because the stiff fluid energy density decreases with the scale factor more rapidly than radiation, it produces a relatively larger change in the primordial helium-4 abundance than in the other element abundances, relative to the changes produced by an additional radiation component. We show that the helium-4 abundance varies linearly with the density of the stiff fluid at a fixed fiducial temperature. Taking {rho}{sub S10} and {rho}{sub R10} to be the stiff fluid energy density and the standard density in relativistic particles, respectively, at T=10 MeV, we find that the change in the primordial helium abundance is well-fit by {Delta}Y{sub p}=0.00024({rho}{sub S10}/{rho}{sub R10}). The changes in the helium-4 abundance produced by additional radiation or by a stiff fluid are identical when these two components have equal density at a 'pivot temperature', T{sub *}, where we find T{sub *}=0.55 MeV. Current estimates of the primordial {sup 4}He abundance give the constraint on a stiff fluid energy density of {rho}{sub S10}/{rho}{sub R10}<30.

• OSTI ID: 21467385
• Journal Information: Physical Review. D, Particles Fields, Vol. 82, Issue 8; Other Information: DOI: 10.1103/PhysRevD.82.083501; (c) 2010 American Institute of Physics; ISSN 0556-2821
• Country of Publication: United States
• Language: English

Related Subjects

73 NUCLEAR PHYSICS AND RADIATION PHYSICS
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
COSMOLOGICAL MODELS
DENSITY
ELEMENT ABUNDANCE
ENERGY DENSITY
HELIUM 4
MEV RANGE 01-10
NUCLEOSYNTHESIS
RELATIVISTIC RANGE
SIMULATION
ABUNDANCE
ENERGY RANGE
EVEN-EVEN NUCLEI
HELIUM ISOTOPES
ISOTOPES
LIGHT NUCLEI
MATHEMATICAL MODELS
MEV RANGE
NUCLEI
PHYSICAL PROPERTIES
STABLE ISOTOPES
SYNTHESIS