We show that charged particles decaying in the early Universe can induce a scale-dependent or running spectral index in the small-scale linear and nonlinear matter power spectrum and discuss examples of this effect in minimal supersymmetric models in which the lightest neutralino is a viable cold-dark-matter candidate. We find configurations in which the neutralino relic density is set by coannihilations with a long-lived stau and the late decay of staus partially suppresses the linear matter power spectrum. Nonlinear evolution on small scales then causes the modified linear power spectrum to evolve to a nonlinear power spectrum similar to (but different in detail) models parametrized by a constant running alpha(s)=dn(s)/dlnk by redshifts of 2 to 4. Thus, Lyman-alpha forest observations, which probe the matter power spectrum at these redshifts, might not discriminate between the two effects. However, a measurement of the angular power spectrum of primordial 21-cm radiation from redshift zapproximate to30-200 might distinguish between this charged-decay model and a primordial running spectral index. The direct production of a long-lived charged particle at future colliders is a dramatic prediction of this model.
A running spectral index in supersymmetric dark-matter models with quasistable charged particles / Profumo, S; Sigurdson, K; Ullio, Piero; Kamionkowski, M.. - In: PHYSICAL REVIEW D, PARTICLES, FIELDS, GRAVITATION, AND COSMOLOGY. - ISSN 1550-7998. - 71:2(2005), pp. 023518.1-023518.15. [10.1103/PhysRevD.71.023518]
A running spectral index in supersymmetric dark-matter models with quasistable charged particles
Ullio, Piero;
2005-01-01
Abstract
We show that charged particles decaying in the early Universe can induce a scale-dependent or running spectral index in the small-scale linear and nonlinear matter power spectrum and discuss examples of this effect in minimal supersymmetric models in which the lightest neutralino is a viable cold-dark-matter candidate. We find configurations in which the neutralino relic density is set by coannihilations with a long-lived stau and the late decay of staus partially suppresses the linear matter power spectrum. Nonlinear evolution on small scales then causes the modified linear power spectrum to evolve to a nonlinear power spectrum similar to (but different in detail) models parametrized by a constant running alpha(s)=dn(s)/dlnk by redshifts of 2 to 4. Thus, Lyman-alpha forest observations, which probe the matter power spectrum at these redshifts, might not discriminate between the two effects. However, a measurement of the angular power spectrum of primordial 21-cm radiation from redshift zapproximate to30-200 might distinguish between this charged-decay model and a primordial running spectral index. The direct production of a long-lived charged particle at future colliders is a dramatic prediction of this model.File | Dimensione | Formato | |
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