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Baryon Asymmetry and Dark Matter

M. Bolz, W. Buchmüller, M. Plümacher

TL;DR

The paper examines whether a large baryogenesis temperature $T_B \sim 10^{10}$ GeV, expected from leptogenesis, can be reconciled with supersymmetric cosmology given gravitino constraints. It computes gravitino production in the thermal bath, derives the yield $Y_{\tilde{G}}$ and relic density $\Omega_{\tilde{G}} h^2$ in the MSSM, particularly for $m_{\tilde{G}} \ll m_{\tilde{g}}$. Applying BBN bounds on late decays, it shows that a conventional unstable gravitino with such $T_B$ typically overproduces energy density or disrupts nucleosynthesis, unless the LSP is gravitino and the NSP is a higgsino-like neutralino in a narrow mass range. Within these conditions, a gravitino LSP with a higgsino-like NSP in $80$–$300$ GeV can yield an acceptable $\Omega h^2$ and a viable $T_B$, making gravitinos viable dark matter candidates for $T_B$ up to $\mathcal{O}(10^{10})$ GeV depending on parameters.

Abstract

We study the implications of a large baryogenesis temperature, $T_B = O(10^{10}$ GeV), on the mass spectrum of superparticles in supersymmetric extensions of the standard model. Models with a neutralino as lightest superparticle (LSP) are excluded. A consistent picture is obtained with the gravitino as LSP, followed by a higgsino-like neutralino (NSP). Gravitinos with masses from 10 to 100 GeV may be the dominant component of dark matter.

Baryon Asymmetry and Dark Matter

TL;DR

The paper examines whether a large baryogenesis temperature GeV, expected from leptogenesis, can be reconciled with supersymmetric cosmology given gravitino constraints. It computes gravitino production in the thermal bath, derives the yield and relic density in the MSSM, particularly for . Applying BBN bounds on late decays, it shows that a conventional unstable gravitino with such typically overproduces energy density or disrupts nucleosynthesis, unless the LSP is gravitino and the NSP is a higgsino-like neutralino in a narrow mass range. Within these conditions, a gravitino LSP with a higgsino-like NSP in – GeV can yield an acceptable and a viable , making gravitinos viable dark matter candidates for up to GeV depending on parameters.

Abstract

We study the implications of a large baryogenesis temperature, GeV), on the mass spectrum of superparticles in supersymmetric extensions of the standard model. Models with a neutralino as lightest superparticle (LSP) are excluded. A consistent picture is obtained with the gravitino as LSP, followed by a higgsino-like neutralino (NSP). Gravitinos with masses from 10 to 100 GeV may be the dominant component of dark matter.

Paper Structure

This paper contains 4 sections, 15 equations, 2 figures, 1 table.

Table of Contents

  1. Introduction
  2. Gravitino density
  3. Constraints from nucleosynthesis
  4. Mass spectrum of superparticles

Figures (2)

  • Figure 1: Upper and lower bounds on the NSP mass as function of the gravitino mass. The full lines represent the upper bound on the gluino mass $m_{\tilde{g}}(\mu) > m_{NSP}$ for different reheating temperatures. The dashed line is the lower bound on $m_{NSP}$ which follows from the NSP lifetime. A higgsino-like NSP with a mass in the shaded area satisfies all cosmological constraints including those from primordial nucleosynthesis.
  • Figure 2: Contribution of gravitinos to the density parameter $\Omega h^2$ for different gravitino masses $m_{\tilde{G}}$ as function of the reheating temperature $T_B$. The gluino mass has been set to $m_{\tilde{g}}(\mu)=500$ GeV.