Motivated by the NANOGrav 15 year data and other recent investigations of stochastic
gravitational background radiation based on pulsar timing arrays, we show how superheavy …

A bstract We explore a variety of composite topological structures that arise from the
spontaneous breaking of SO (10) to SU (3) c× U (1) em via one of its maximal subgroups SU …

Proton decay is a smoking gun signature of grand unified theories (GUTs). Searches by
Super-Kamiokande have resulted in stringent limits on the GUT symmetry-breaking scale …

A bstract Grand Unified Theories (GUT) predict proton decay as well as the formation of
cosmic strings which can generate gravitational waves. We determine which non …

Topological defects can act as local impurities that seed cosmological phase transitions. In
this Letter, we study the case of domain walls and how they can affect the electroweak …

We discuss how in SO (10) grand unification an observable number density of topologically
stable intermediate mass (∼ 10 14 GeV) monopoles survive inflation driven by a Coleman …

Inspired by the recent determination of the W-boson mass by the CDF collaboration, we
revisit an SO (10) axion model in which a scalar SU (2) L triplet field with zero hypercharge …

We estimate the stochastic gravitational wave spectrum emitted from a network of cosmic
strings in which the latter are effectively stable against breaking by monopole pair creation …

A bstract In this paper we discuss SU (5) 3 with cyclic symmetry as a possible grand unified
theory (GUT). The basic idea of such a tri-unification is that there is a separate SU (5) for …

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 …