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Gauge mediation in supergravity and gravitino dark matter

Masahiro Ibe, Ryuichiro Kitano

TL;DR

The paper proposes a gravity-stabilized, simple gauge mediation model featuring a singlet $S$ and messenger fields to address gravitino cosmology and the $\mu$-problem. It shows that $S$ dynamics in the early universe lead to a SUSY-breaking vacuum, and that $S$ decays produce gravitinos in a controlled, non-thermal way whose relic density can match the observed dark matter, largely independent of the thermal history. The two-parameter framework yields concrete relations between $m_S$, $m_{3/2}$, and MSSM gaugino masses, with gravitino production governed by decay channels $S\to hh$ or $gg$ and a calculable $T_d$ that typically lies around the MeV scale. Entropy production from $S$ decay dilutes unwanted relics and allows possible baryogenesis, offering a cosmologically viable picture that links SUSY breaking, dark matter, and grand-unified motivations.

Abstract

Gravitinos and hidden sector fields often cause a cosmological disaster in supersymmetric models. We find that a model with gravitational gauge mediation solves such a problem quite naturally. The mu-problem is also absent in the model. Moreover, the abundance of gravitinos explains correct amount of dark matter of the universe. The dark matter abundance can be calculated without detailed information on the thermal history of the universe such as the reheating temperature after inflation.

Gauge mediation in supergravity and gravitino dark matter

TL;DR

The paper proposes a gravity-stabilized, simple gauge mediation model featuring a singlet and messenger fields to address gravitino cosmology and the -problem. It shows that dynamics in the early universe lead to a SUSY-breaking vacuum, and that decays produce gravitinos in a controlled, non-thermal way whose relic density can match the observed dark matter, largely independent of the thermal history. The two-parameter framework yields concrete relations between , , and MSSM gaugino masses, with gravitino production governed by decay channels or and a calculable that typically lies around the MeV scale. Entropy production from decay dilutes unwanted relics and allows possible baryogenesis, offering a cosmologically viable picture that links SUSY breaking, dark matter, and grand-unified motivations.

Abstract

Gravitinos and hidden sector fields often cause a cosmological disaster in supersymmetric models. We find that a model with gravitational gauge mediation solves such a problem quite naturally. The mu-problem is also absent in the model. Moreover, the abundance of gravitinos explains correct amount of dark matter of the universe. The dark matter abundance can be calculated without detailed information on the thermal history of the universe such as the reheating temperature after inflation.

Paper Structure

This paper contains 12 sections, 55 equations, 2 figures.

Table of Contents

  1. Introduction
  2. A simple model of gauge mediation
  3. Gravitational gauge mediation
  4. $\mu$-term driven supersymmetry breaking
  5. Cosmological evolution of $S$
  6. Gravitino dark matter
  7. Interaction Lagrangian of the $S$ field
  8. $S$ decays and gravitino production
  9. Are gravitinos cold?
  10. Entropy production and baryogenesis
  11. Summary
  12. Initial condition of $S$

Figures (2)

  • Figure 1: A typical evolution of the $S$ field (left) and time dependence of the amplitude $|S|$ (right) for $m_{S} = 400$ GeV, $m_{3/2}=500$ MeV and $\lambda = 10^{-3}$.
  • Figure 2: The parameter regions of the model ($N=1$) which account for the dark matter component of the universe. The correct amount of gravitino dark matter can be obtained within the allowed range of parameter space. Below the dot-dashed line in the left figure, the decay mode of $S$ into two Higgs boson is closed (Case (B)). The constraint from the lower bound on the decay temperature $T_d > 2$ MeV is indicated. The contour of $T_d = 5$ MeV is also shown. In the right figure, the decay mode $S \to hh$ is open above the dot-dashed line (Case (A)). The decay mode into two Binos is open in the right-lower region.