Eur. Phys. J. C (2014) 74: 2730
https://doi.org/10.1140/epjc/s10052-014-2730-9

Regular Article - Theoretical Physics

Number of fermion generations from a novel grand unified model

¹ Saha Institute of Nuclear Physics, Kolkata, 700064, India
² Departamento de Física and Centro de Física Teórica de Partículas (CFTP), Instituto Superior Técnico (IST), Universidade de Lisboa, Av. Rovisco Pais, 1049-001, Lisbon, Portugal

^* e-mail: david.costa@tecnico.ulisboa.pt

Received: 31 October 2013
Accepted: 23 December 2013
Published online: 31 January 2014

Abstract

Electroweak interactions based on the gauge group , coupled to the QCD gauge group , can predict the number of generations to be multiples of three. We first try to unify these models within groups, using antisymmetric tensor representations only. After examining why these attempts fail, we continue to search for an GUT that can explain the number of fermion generations. We show that such a model can be found for , with fermions in antisymmetric rank-1 and rank-3 representations only, and we examine the constraints on various masses in the model coming from the requirement of unification.