Colóquio do PPGF: 25 de setembro de 2026
Colóquio #04 2026.2
O Programa de Pós-Graduação em Física (PPGF) realizará, na próxima sexta-feira, 25 de setembro de 2026, mais uma edição de seu colóquio.
Nesta semana, o encontro será dividido em três apresentações, com 20 minutos destinados a cada exposição. O colóquio contará com a participação de pesquisadores do México, que estão em visita acadêmica à Universidade Federal da Paraíba (UFPB).
Sexta-feira, 25 de setembro de 2026, às 14h, no Auditório 2 do Prédio da Pós-Graduação em Física/CCEN.
Localization of a Weyl invariant action into a Principal Bundle
Dr. José Carlos Zamarripa Rodríguez
Departamento de matemáticas
Centro Universitario de Ciencias Exactas e Ingeniería
Universidad de Guadalajara, México
This talk presents a geometric construction of a principal bundle (P) as an extension of Weyl-Integrable geometry. Starting from a base manifold (M) and the introduction of an additional fiber, we define the principal-bundle connection and the associated decomposition of the tangent space into horizontal and vertical subspaces. This construction provides a framework for relating the geometry of the total space to the underlying Weyl-Integrable structure of the base manifold (M). Finally, the divergence problem emerging from this formulation is briefly examined, together with two possible approaches to addressing it.
Gravity from Invariant Weyl-Integrable space-time (IWIST)
Dr. José Edgar Madriz Aguilar
Departamento de Matemáticas
Centro Universitario de Ciencias Exactas e Ingenierías
Universidad de Guadalajara, México.
In this talk I present a geometrically motivated formulation of gravity in an invariant Weyl-Integrable space-time (IWIST), in which the background geometry is not imposed a priori but is dynamically determined through the Palatini variational principle. For a scalar field non-minimally coupled to gravity action, the resulting compatibility condition defines a Weyl-Integrable geometry which is preserved by a local Weyl transformation of the metric and the geometrical scalar field. We construct an action invariant under both diffeomorphisms and Weyl transformations and introduce a Weyl-covariant variational procedure based on an invariant extension of the divergence theorem. The corresponding field equations are obtained for the metric, the Weyl scalar, and the Weyl gauge field. We further formulate the theory in the Einstein–Riemann frame, where the effective metric is Riemannian and the scalar field is reinterpreted as a physical degree of freedom of geometric origin. Finally, we propose a geometrical mechanism for a explicit breaking of Weyl symmetry by introducing a coupling between the Weyl gauge field and a current constructed from the scalar sector. The resulting theory remains diffeomorphism covariant while departing from local Weyl invariance. The Einstein-Riemann representation of the broken theory contains an additional generally covariant interaction, making the Weyl-invariant model a particular limit of a more general gravitational theory.
A novel pre-inflationary model in view of the lack of angular correlation in the CMB
Alfonso Bernal Tirado
Departamento de Ciencias exactas y Naturales
Centro Universitario de los Valles
Universidad de Guadalajara, México.
In this presentation, we propose a new unified pre-inflationary–inflationary model of theUniverse motivated by recent Planck satellite observations. The Planck mission reported a lack of correlation in the two-point angular correlation function at large angular separations, a feature associated with a cutoff in the primordial power spectrum and a delayed onset of inflation. With the aim of addressing these issues, we propose a model in which the pre-inflationary era begins at the Planck time and is followed by an inflationary period. During this first phase, the Universe undergoes a decelerated expansion that transitions into na accelerated one, ending in a de Sitter stage at which inflation begins. Throughout this pre-inflationary phase, the horizon grows while causally disconnected modes of the pre-inflaton field remain causally disconnected, naturally explaining the lack of angular correlation observed in the CMB by Planck.
