Related papers: Vacuum energy and cosmological constant in QFT in …
The cosmological term, $\Lambda$, in Einstein's equations is an essential ingredient of the `concordance' $\Lambda$CDM model of cosmology. In this mini-review presentation, we assess the possibility that $\Lambda$ can be a dynamical…
It is well-known that quantum field theory (QFT) induces a huge value of the cosmological constant, $\Lambda$, which is outrageously inconsistent with cosmological observations. We review here some aspects of this fundamental theoretical…
A substantial body of phenomenological and theoretical work over the last few years strengthens the possibility that the vacuum energy density (VED) of the universe is dynamical, and in particular that it adopts the `running vacuum model'…
The $\Lambda$-term in Einstein's equations is a fundamental building block of the `concordance' $\Lambda$CDM model of cosmology. Even though the model is not free of fundamental problems, they have not been circumvented by any alternative…
The cosmological constant term, $\Lambda$, in Einstein's equations has been for three decades a building block of the concordance or standard $\Lambda$CDM model of cosmology. Although the latter is not free of fundamental problems, it…
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…
In this thesis we present detailed analyses on various running vacuum models (RVM's), in which the vacuum energy density "runs" with the cosmic expansion. The RVM's are motivated from the renormalization group formalism of Quantum Field…
An expanding universe is not expected to have a static vacuum energy density. The so-called cosmological constant $\Lambda$ should be an approximation, certainly a good one for a fraction of a Hubble time, but it is most likely a temporary…
In this year, in which we celebrate 100 years of the cosmological term, $\Lambda$, in Einstein's gravitational field equations, we are still facing the crucial question whether $\Lambda$ is truly a fundamental constant or a mildly evolving…
I review the excellent phenomenological status of a class of dynamical vacuum models in which the vacuum energy density, $\rho_{\Lambda}=\rho_{\Lambda}(H)$, as a function of the Hubble rate, evolves through its interaction with dark matter…
Within the $\Lambda$CDM cosmological model, the absolute value of Einstein's cosmological constant $\Lambda$, sometimes expressed as the gravitating mass-energy density $\rho_\Lambda$ of the physical vacuum, is a fundamental constant of…
Despite the fact that a rigid $\Lambda$-term is a fundamental building block of the concordance $\Lambda$CDM model, we show that a large class of cosmological scenarios with dynamical vacuum energy density $\rho_{\Lambda}$ and/or…
We construct the cosmological model to explain the cosmological constant problem. We built the extension of the standard cosmological model $\Lambda$CDM by consideration of decaying vacuum energy represented by the running cosmological…
The possibility that the vacuum energy density (VED), $\rho_{\rm vac}$, could be time dependent in the expanding Universe is intuitively more reasonable than just a rigid cosmological constant for the entire cosmic history. The dynamics of…
Phenomenological work in the last few years has provided significant support to the idea that the vacuum energy density (VED) is a running quantity with the cosmological evolution and that this running helps to alleviate the cosmological…
Despite the outstanding achievements of modern cosmology, the classical dispute on the precise value of $H_0$, which is the first ever parameter of modern cosmology and one of the prime parameters in the field, still goes on and on after…
Inflation is a necessary cosmic mechanism to cure basic inconsistencies of the standard model of cosmology. These problems are usually `fixed' by postulating the existence of a scalar field (called the ``inflaton''). However, other less ad…
Next year we will celebrate 100 years of the cosmological term, $\Lambda$, in Einstein's gravitational field equations, also 50 years since the cosmological constant problem was first formulated by Zeldovich, and almost about two decades of…
Recent studies of QFT in cosmological spacetime indicate that the speeding up of the present universe may not just be associated with a rigid cosmological term but with a running one that evolves with the expansion rate:…
The cosmological term, $\Lambda$, was introduced $104$ years ago by Einstein in his gravitational field equations. Whether $\Lambda$ is a rigid quantity or a dynamical variable in cosmology has been a matter of debate for many years,…