Kavli Affiliate: Satoshi Shirai
| First 5 Authors: Akifumi Chitose, Masahiro Ibe, Shunsuke Neda, Satoshi Shirai,
| Summary:
Recent observations by pulsar timing arrays (PTAs) indicate a potential
detection of a stochastic gravitational wave (GW) background. Metastable cosmic
strings have been recognized as a possible source of the observed signals. In
this paper, we propose an $R$-invariant supersymmetric new inflation model. It
is characterized by a two-step symmetry breaking $mathrm{SU}(2) to
mathrm{U}(1)_G to mathrm{nothing}$, incorporating metastable cosmic strings.
The field responsible for the initial symmetry breaking acts as the inflaton,
while the second symmetry breaking occurs post-inflation, ensuring the
formation of the cosmic string network without monopole production. Our model
predicts symmetry breaking scales consistent with the string tensions favored
by PTA data, $G_mathrm{N} mu_mathrm{str} sim 10^{-5}$, where $G_mathrm{N}$
is the Newton constant. Notably, a low reheating temperature is required to
suppress non-thermal gravitino production from the decay of inflaton sector
fields. This also helps evading LIGO-Virgo-KAGRA constraints, while yielding a
distinctive GW signature that future PTA and interferometer experiments can
detect. Additionally, we examine the consistency of this scenario with
non-thermal leptogenesis and supersymmetric dark matter.
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