Στην αίθουσα “Αιμίλιος Χαρλαύτης” του ΙΑΑΔΕΤ στη Πεντέλη. Δευτέρα 18.09.2023, ώρα 12:00.

Ομιλητής: Dr. Joan Solà Peracaula, Departament d’Estructura i Constituents de la Matèria (ECM). Institut de Ciències del Cosmos, University of Barcelona.

Abstract: The possibility that the vacuum energy density (VED) could be time dependent in the expanding Universe is intuitively more reasonable than just a rigid cosmological constant for the entire cosmic history. The framework of the running vacuum model (RVM) is a successful example, in which the VED is a power series of the Hubble rate, H(t), and its derivatives. The RVM contributes to alleviate cosmological problems and tensions with the data, having also implications on the so-called fundamental `constants’ of Nature, which should be slowly drifting with the cosmic expansion owing to the fluctuations of the quantum vacuum. This includes the cosmological `constant’, Lambda, the gravitational `constant’, G, the gauge and Yukawa couplings as well as the particle masses themselves (both of dark matter and baryonic matter). The subtle exchange of energy involved is the basis for the “micro and macro connection”. In this talk, I will discuss not only this connection as a possibility but show that it is in fact a generic prediction of QFT in cosmological spacetime. This fact has not been pointed out until recently when an appropriate renormalization framework for the VED has been found which is free from the usual conundrums associated with the cosmological constant problem.