Date: Tuesday October 14
Venue: SALÓN MERIDIANO de la Facultad de Ciencias Astronómicas y Geofísicas de la Universidad Nacional de La Plata. Argentina.
PROGRAM:
10:00 - 10:45 hs: Nicolas Grandi (IFLP/UNLP)
Title: De Sitter geometric inflation from dynamical singularities
Abstract: Within the framework of geometric inflation, where the Friedmann equation is modified to incorporate an infinite series of higher curvature corrections arising from quantum fluctuations, we describe the emergence of a de Sitter inflationary phase near the poles of an arbitrary dynamical function. Our analysis is quite general and does not depend on any specific choice of cosmological dynamics.
10:45 - 11:15 hs: Coffe
11:15 - 12 hs: Franciso Plaza (FCAG/UNLP)
Title: Unimodular Gravity Cosmology: Constraints from DESI DR2 and Complementary Observations
Abstract: Motivated by the recent baryon acoustic oscillation measurements from the DESI DR2 collaboration, in this talk we present an extended analysis of a cosmological model based on holographic dark energy within the framework of Unimodular Gravity (UG). In this setting, UG allows us to account for the accelerated expansion of the Universe through the modified gravitational dynamics themselves, while permitting spacetime variations in the effective cosmological constant. We confront the model with a wide range of observations, from Type Ia supernovae and baryon acoustic oscillations (DESI DR2) to quasars and Planck CMB data. We will discuss whether this framework alleviates the Hubble tension and how it compares to the standard $\Lambda$CDM model in terms of Bayesian model selection.
12 - 13:30 hs: Lunch
13:30 - 14:15 hs: Ilya Shapiro (Universidade Federal de Juiz de Fora, MG,Brazil)
Title: Cosmological Constant and Renormalization Group Running in the IR
Abstract: The Cosmological Constant (CC) Problem emerges in Quantum Field Theory (QFT) in curved space-time owing to the enormous magnitude of the induced vacuum energy. The CC Problem looks rather complicated, such that its solution from the first principles is not a realistic perspective, even in a far future. After reviewing the fundamental CC problem, we consider the possibility of a slightly variable CC because of the quantum effects of matter fields. There is no way to calculate relevant quantum contributions directly in the framework of available QFT methods. However, three different approaches converge to the unique form of the possible running of CC and the effective Newton constant G in the low-energy limit. Assuming covariance, or the standard quadratic decoupling of massive fields at low energies, or using dimensional arguments, we arrive at the unique form of a running, which leads to the relatively simple cosmological model with potentially observable predictions. A very recent result is that the possible running, with a single phenomenological parameter may be useful in alleviating various tensions existing nowadays in cosmology.
14:15 - 15:15 hs: Coffe
15:15 - 16:00 hs: Sebastián Franchino-Viñas (IFLP)
Title: Quantum physics in strong fields
Abstract: Quantum field theory in the presence of strong backgrounds, be them electromagnetic or gravitational, is acquiring a central rôle in the understanding of the primordial universe and laser laboratory experiments. The interaction of quantum fields with classical backgrounds gives rise to a variety of fundamental effects. In such extreme environments, we will describe the prediction and current quest of effects such as birefringence and pair creation.