Grand Unified Theories (GUTs) are one of the most interesting high-energy completions of
the Standard Model, because they provide a rich, powerful and elegant group-theoretical …

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 …

The idea of reduction of couplings in renormalizable theories will be presented and then will
be applied in Particle Physics models. Reduced couplings appeared as functions of a …

We present a four-dimensional string model whose effective field theory has an O (6)× O (4)
gauge symmetry which is broken to the standard model at a very high scale. The fermions of …

We show how hybrid inflation can be successfully realized in a supersymmetric model with
gauge group GPS= SU (4) c× SU (2) L× SU (2) R. By including a non-renormalizable …

We study flipped SU (5)× U (1) grand unified theories (GUTs) with Γ 3≃ A 4 modular
symmetry. We propose two models with different modular weights assignments, where the …

A bstract We analyse the gravitational wave and low energy signatures of a Pati-Salam
phase transition. For a Pati-Salam scale of M PS∼ 10 5 GeV, we find a stochastic power …

A bstract Genetic Algorithms are introduced as a search method for finding string vacua with
viable phenomenological properties. It is shown, by testing them against a class of Free …

In the context of the free-fermionic formulation of the heterotic superstring, we construct a
three-generation N= 1 supersymmetric SU (4)× SU (2) L× SU (2) R model supplemented by …

We construct concrete supersymmetric grand unified theories based on the Pati–Salam
gauge group SU (4) c× SU (2) L× SU (2) R which naturally lead to a moderate violation of …