Logo
ScienceStack
Table of Contents
Fetching ...
Sign In

Wino Cold Dark Matter from Anomaly-Mediated SUSY Breaking

Takeo Moroi, Lisa Randall

TL;DR

This paper demonstrates that anomaly-mediated SUSY breaking with a sequestered sector resolves the cosmological moduli problem by yielding heavy moduli whose decays occur before BBN, while predicting a Wino-like LSP. The authors show that modulus decay can produce the right relic abundance of Wino CDM, thanks to enhanced $s$-wave annihilation and controlled LSP production per decay, with $m_\phi \sim 100$–300 TeV and $\Omega_\chi h^2$ in the 0.1–1 range for natural parameters. They further argue that Wino CDM has favorable detection prospects: relatively large Higgs-exchange scattering cross sections give $R\sim 0.01$–$0.1$~events/kg/day in Ge detectors, and distinctive high-energy positron and neutrino signals are testable by AMS and neutrino telescopes. The work highlights a testable pathway where a heavy-modulus, anomaly-mediated framework yields a viable CDM candidate with strong experimental signatures, linking early-un Universe cosmology to near-future dark matter searches.

Abstract

The cosmological moduli problem is discussed in the framework of sequestered sector/anomaly-mediated supersymmetry (SUSY) breaking. In this scheme, the gravitino mass (corresponding to the moduli masses) is naturally 10 - 100 TeV, and hence the lifetime of the moduli fields can be shorter than $\sim 1 sec$. As a result, the cosmological moduli fields should decay before big-bang nucleosynthesis starts. Furthermore, in the anomaly-mediated scenario, the lightest superparticle (LSP) is the Wino-like neutralino. Although the large annihilation cross section means the thermal relic density of the Wino LSP is too small to be the dominant component of cold dark matter (CDM), moduli decays can produce Winos in sufficient abundance to constitute CDM. If Winos are indeed the dark matter, it will be highly advantageous from the point of view of detection. If the halo density is dominated by the Wino-like LSP, the detection rate of Wino CDM in Ge detectors can be as large as $0.1 - 0.01$ event/kg/day, which is within the reach of the future CDM detection with Ge detector. Furthermore, there is a significant positron signal from pair annihilation of Winos in our galaxy which should give a spectacular signal at AMS.

Wino Cold Dark Matter from Anomaly-Mediated SUSY Breaking

TL;DR

This paper demonstrates that anomaly-mediated SUSY breaking with a sequestered sector resolves the cosmological moduli problem by yielding heavy moduli whose decays occur before BBN, while predicting a Wino-like LSP. The authors show that modulus decay can produce the right relic abundance of Wino CDM, thanks to enhanced -wave annihilation and controlled LSP production per decay, with –300 TeV and in the 0.1–1 range for natural parameters. They further argue that Wino CDM has favorable detection prospects: relatively large Higgs-exchange scattering cross sections give –~events/kg/day in Ge detectors, and distinctive high-energy positron and neutrino signals are testable by AMS and neutrino telescopes. The work highlights a testable pathway where a heavy-modulus, anomaly-mediated framework yields a viable CDM candidate with strong experimental signatures, linking early-un Universe cosmology to near-future dark matter searches.

Abstract

The cosmological moduli problem is discussed in the framework of sequestered sector/anomaly-mediated supersymmetry (SUSY) breaking. In this scheme, the gravitino mass (corresponding to the moduli masses) is naturally 10 - 100 TeV, and hence the lifetime of the moduli fields can be shorter than . As a result, the cosmological moduli fields should decay before big-bang nucleosynthesis starts. Furthermore, in the anomaly-mediated scenario, the lightest superparticle (LSP) is the Wino-like neutralino. Although the large annihilation cross section means the thermal relic density of the Wino LSP is too small to be the dominant component of cold dark matter (CDM), moduli decays can produce Winos in sufficient abundance to constitute CDM. If Winos are indeed the dark matter, it will be highly advantageous from the point of view of detection. If the halo density is dominated by the Wino-like LSP, the detection rate of Wino CDM in Ge detectors can be as large as event/kg/day, which is within the reach of the future CDM detection with Ge detector. Furthermore, there is a significant positron signal from pair annihilation of Winos in our galaxy which should give a spectacular signal at AMS.

Paper Structure

This paper contains 5 sections, 33 equations, 2 figures, 1 table.

Table of Contents

  1. Introduction
  2. Mass Density of the Wino LSP
  3. Detecting Wino CDM
  4. Conclusion
  5. Moduli Field Couplings

Figures (2)

  • Figure 1: Contours of the constant $\Omega_\chi h^2$ on $m_\chi$ vs. $\bar{N}_{\rm LSP}$ plane. Numbers in the figure are $\Omega_\chi h^2$. Here, we take $\Lambda_{\rm eff}=M_*$ and $m_\phi=100~\hbox{TeV}$.
  • Figure 3: Contours of the constant detection rate $R$ in $^{76}$Ge detector on $m_\chi$ vs. $\tan\beta$ plane. We take the parameters of $\mu =2m_{\rm G2}$, $m_h={\rm 100~GeV}$, $m_H={\rm 300~GeV}$, $E_{\rm thr}={\rm 2~keV}$, $\bar{v}_\chi={\rm 320~km/sec}$ and $\rho_\chi^{\rm (halo)}={\rm 0.3~GeV/cm^3}$.