相关论文: Dpes massless QCD have vacuum energy?
As evidenced by a great number of works, it is common practice to assume that the Universe is flat. However, the majority of studies which make use of observational data to constrain the curvature density parameter are premised on the…
Within some approaches to loop quantum cosmology, the existence of an Euclidean phase at high density has been suggested. In this article, we try to explain clearly what are the observable consequences of this possible disappearance of…
Euclidean dense matter generically suffers from the fermion sign problem. However, we argue that the sign problem is absent if one considers only low-energy degrees of freedom. Specifically, the low energy effective theory of dense QCD has…
An interaction between the vacuum energy and dark matter is an intriguing possibility which may offer a way of solving the cosmological constant problem. Adopting a general prescription for momentum exchange between the two dark components,…
It is widely believed that as one of the candidates for dark energy, the cosmological constant should relate directly with the quantum vacuum. Despite decades of theoretical effects, however, there is still no quantitative interpretation of…
If the mechanism responsible for the smallness of the vacuum energy is consistent with local quantum field theory, general arguments suggest the existence of at least one unobserved scalar particle with Compton wavelength bounded from below…
Lattice QCD results relevant to heavy quark physics are reviewed. In particular new results will be shown that, for the first time, include dynamical quarks in the QCD vacuum which are close enough to being realistic to allow accurate…
Recently there have been claims on model-independent evidence of dynamical dark energy. Herein we consider a fairly general class of cosmological models with a time-evolving cosmological term of the form $\Lambda(H)=C_0+C_H H^2+C_{\dot{H}}…
Arguably a major success of the landscape picture is the prediction of a small, non-zero vacuum energy density. The details of this prediction depends in part on how the diverging spacetime volume of the multiverse is regulated, a question…
Describing the presently observable Universe as a self-sustained condensate of gravitons of size $H_0^{-1}$, with large occupation number $N$, we argue that the most probable value for the quantum vacuum energy is of the order of the…
The interaction between the quantum vacuum and a weak gravitational field is calculated for the vacuum fields of quantum electrodynamics. The result shows that the vacuum state is modified by the gravitational field, giving rise to a…
The idea of a `condensed' vacuum state is generally accepted in modern elementary particle physics. We argue that this should motivate a new generation of precise `ether-drift' experiments with present-day technology.
The positivity of the integrand of certain Euclidean space functional integrals implies that the free energy per unit volume for QCD with a baryon chemical potential $\mu_B$ (and zero isospin chemical potential) is greater than the free…
The latest cosmological constraints on the sum of the neutrino masses depend on prior physical assumptions about the mass spectrum. To test the accordance of cosmological and laboratory constraints in the absence of such priors, we…
A discussion is made of the strategy to check dual superconductivity of the vacuum as a mechanism of colour confinement. Recent evidence from Lattice is reviewed.
The properties of the vacuum are addressed in the two- and four-dimensional quark models for QCD. It is demonstrated that the two-dimensional QCD ('t Hooft model) possesses only one possible vacuum state - the solution to the mass-gap…
In infrared-stable fixed-point field theories, the interaction energy of a test particle is proportional to the non-relativistic (heavy source) coordinate-space potential derived from the field strength produced by that source. This is no…
We review the cosmological evidence for a low matter density universe and a cosmological constant or dynamical vacuum energy and address the cosmolog$ coincidence problem: why is the matter density about one-half the vacuum energy {\em…
The Einstein equation in a semi-classical approximation is applied to a spherical region of the universe, with the stress-energy tensor consisting of the mass density and pressure of the LambdaCDM cosmological model plus an additional…
The quartic-divergent vacuum energy poses an ultraviolet (UV) challenge (the cosmological constant problem) in probing the nature of dark energy. Here we try to evaluate the contribution of the vacuum energy to dark energy with a method of…