Abstract
We study the spontaneous R-symmetry breaking model and investigate thecosmological constraints on this model due to the pseudoNambu-Goldstone boson, R-axion. We consider the R-axion which hasrelatively heavy mass in order to complement our previous work. In thisregime, model parameters, R-axions mass and R-symmetry breaking scale,are constrained by Big Bang Nucleosynthesis and overproduction of the gravitino produced from R-axion decay and thermal plasma.We find that the allowed parameter space is very small forhigh reheating temperature.For low reheating temperature,the U(1)R breaking scale fa is constrained asfa < 1012−14 GeV regardless of the value of R-axion mass.
Highlights
Supersymmetry (SUSY) is one of the most promising candidates of the physics beyond the standard model (SM) because it can relax the naturalness problem and suggests the gauge coupling unification
In our previous study [8], we focused on relatively light and long-lived R-axions since such parameter regions are favored in the context of “low-scale gauge mediation” [12], where various cosmological constraints including the Big Bang Nucleosynthesis (BBN), the Cosmic Microwave Background (CMB), cosmic γ-ray and the re-ionization can be imposed in the late epoch of the expanding universe
We considered the spontaneous R-symmetry breaking model and investigated the cosmological constraints of heavy R-axion which can decay to hadrons
Summary
Supersymmetry (SUSY) is one of the most promising candidates of the physics beyond the standard model (SM) because it can relax the naturalness problem and suggests the gauge coupling unification. In our previous study [8], we focused on relatively light and long-lived R-axions since such parameter regions are favored in the context of “low-scale gauge mediation” [12], where various cosmological constraints including the Big Bang Nucleosynthesis (BBN), the Cosmic Microwave Background (CMB), cosmic γ-ray and the re-ionization can be imposed in the late epoch of the expanding universe In addition to these constraints, we here point out that the abundance of heavier R-axions with shorter lifetime, which can explain the 125 GeV Higgs more can be constrained in a wide range of parameter space by two cosmological constraints: One is coming from hadronic decays of R-axions.
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