Seminario CAPA. lya L. Shapiro (Universidade Federal de Juiz de Fora, MG, Brazil on sabbatical leave at DFTUZ/UNIZAR)

SEMINARIO CAPA

"Cosmological Constant and Renormalization Group Running in the IR"

Ilya L. Shapiro
(Universidade Federal de Juiz de Fora, MG, Brazil
on sabbatical leave at DFTUZ/UNIZAR)

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 possible 
form of a running, which leads to the relatively simple cosmological model with 
potentially observable predictions. Much more recent result is that this possible 
running, with a single phenomenological parameter, may be useful in alleviating 
various tensions existing nowadays in cosmology.

Fecha: jueves, 22 de octubre de 2026
Hora: 12:10 horas
Lugar: Seminario de Física Teórica