6 papers
Fermion Multiplicities at the GUT Scale: A Statistical Study of Unification and Proton Decay
Akifumi Chitose, Ko Hirooka, Masahiro Ibe +1
We study the impact of multiple vector-like fermions in SU(5) grand unified theory (GUT). Threshold effects from extra fermions allow the observed gauge couplings to be consistentl…
Flavor Symmetry and Proton Decay in PeV-Scale Supersymmetry
Akifumi Chitose, Masahiro Ibe, Satoshi Shirai
Supersymmetry beyond the TeV scale offers several theoretical and phenomenological advantages, such as accommodating the observed Higgs mass and alleviating the flavor and CP probl…
Do Cosmic String Segments Emit Gravitational Waves?
Akifumi Chitose, Masahiro Ibe, Shunsuke Neda +1
Cosmic strings are predicted in various extensions of the Standard Model, including grand unified theories. Depending on the symmetry-breaking pattern, they can be either topologic…
Cosmic Strings in Multi-Step Symmetry Breaking
Akifumi Chitose, Masahiro Ibe, Satoshi Shirai +1
We investigate cosmic strings arising from a hierarchical gauge symmetry breaking sequence, $\mathrm{SU}(2) \times \mathrm{U}(1) \rightarrow \mathrm{U}(1) \times \mathrm{U}(1) \rig…
Gravitational Waves from Metastable Cosmic Strings in Supersymmetric New Inflation Model
Akifumi Chitose, Masahiro Ibe, Shunsuke Neda +1
Recent observations by pulsar timing arrays (PTAs) indicate a potential detection of a stochastic gravitational wave (GW) background. Metastable cosmic strings have been recognized…
Revisiting Metastable Cosmic String Breaking
Akifumi Chitose, Masahiro Ibe, Yuhei Nakayama +2
Metastable cosmic strings appear in models of new physics with a two-step symmetry breaking , where and . They decay via the monopole-antimo…