20 research outputs found
Modeling electromagnetic form factors of light and heavy pseudoscalar mesons
The electromagnetic form factors of light and heavy pseudoscalar mesons are
calculated within two covariant constituent-quark models, a light-front and a
dispersion relation approach. We investigate the details and physical origins
of the model dependence of various hadronic observables: the weak decay
constant, the charge radius and the elastic electromagnetic form factor.Comment: 6 pages, 4 figures, use revtex4. Figure 2 and references are
corrected. Acknoledgments are adde
The disruption of proteostasis in neurodegenerative diseases
Cells count on surveillance systems to monitor and protect the cellular proteome which, besides being highly heterogeneous, is constantly being challenged by intrinsic and environmental factors. In this context, the proteostasis network (PN) is essential to achieve a stable and functional proteome. Disruption of the PN is associated with aging and can lead to and/or potentiate the occurrence of many neurodegenerative diseases (ND). This not only emphasizes the importance of the PN in health span and aging but also how its modulation can be a potential target for intervention and treatment of human diseases.info:eu-repo/semantics/publishedVersio
Topological matter: Graphene and superfluid he
Contains fulltext :
128443.pdf (preprint version ) (Open Access
Phenomenology of Effective Gravity
The cosmological constant is not an absolute constant. The gravitating part
of the vacuum energy is adjusted to the energy density of matter and to other
types of the perturbations of the vacuum. We discuss how the vacuum energy
responds (i) to the curvature of space in the Einstein closed Universe; (ii) to
the expansion rate in the de Sitter Universe; and (iii) to the rotation in the
Goedel Universe. In all these steady state Universes, the gravitating vacuum
energy is zero in the absence of the perturbation, and is proportional to the
energy density of perturbation. This is in a full agreement with the
thermodynamic Gibbs-Duhem relation applicable to any quantum vacuum. It
demonstrates that (i) the cosmological constant is not huge, since according to
the Gibbs-Duhem relation the contribution of zero point fluctuations to the
vacuum energy is cancelled by the trans-Planckian degrees of freedom; (ii) the
cosmological constant is non-zero, since the perturbations of the vacuum state
induce the non-zero vacuum energy; and (iii) the gravitating vacuum energy is
on the order of the energy density of matter and/or of other perturbations. We
also consider the vacuum response to the non-steady-state perturbations. In
this case the Einstein equations are modified to include the non-covariant
corrections, which are responsible for the relaxation of the cosmological
constant. The connection to the quintessence is demonstrated. The problem of
the energy-momentum tensor for the gravitational field is discussed in terms of
effective gravity. The difference between the momentum and pseudo-momentum of
gravitational waves in general relativity is similar to that for sound waves in
hydrodynamics.Comment: LaTeX file, 29 pages, no figures, prepared for proceedings of the
COSLAB school in Krakow, 2002; discussion on energy-momentum tensor is
extended, references are adde