Composite topological structures such as superheavy “quasistable strings”(QSS) and “walls
bounded by strings”(WBS) arise in realistic extensions of the Standard Model of high energy …

A series of pulsar timing arrays (PTAs) recently observed gravitational waves at the
nanohertz frequencies. Motivated by this remarkable result, we present a novel class of Pati …

We show that, when connected with monopoles, the flat D-flat direction breaking the local U
(1) BL symmetry as an extension of the minimal supersymmetric standard model can be …

The existence of a stochastic gravitational wave background is indicated by the recent
pulsar timing array (PTA) experiments. We study the enhanced production of second-order …

A realistic model of SU (5)× U (1) χ, embedded in SO (10) supersymmetric grand unified
theory, is investigated for the emergence of a metastable cosmic string network. This …

We discuss E 6 based extensions of the Standard Model (SM) containing two varieties of
superheavy metastable cosmic strings (CSs) that respectively have neutral and electrically …

A bstract We study supersymmetric (SUSY) flipped SU (5)× U (1) unification, focussing on its
predictions for proton decay, fermion masses and gravitational waves. We performed a two …

In a recent paper (Phys. Rev. D 108 (2023) 095053), we have demonstrated that the 2023
PTA results, which hint at a stochastic gravitational wave (GW) background at nanohertz …

A bstract Metastable cosmic strings appear in models of new physics with a two-step
symmetry breaking G→ H→ 1, where π 1 (H)≠ 0 and π 1 (G)= 0. They decay via the …

We consider F-term hybrid inflation (FHI) and SUSY breaking in the context of a B− L
extension of the MSSM that largely respects a global U (1) R symmetry. The hidden sector …