372 research outputs found
A New Perspective on Electroweak Strings
The vortex solution (Z-string) of the electroweak interactions can be
interpreted as the 2-dimensional sphaleron at the top of a non-contractible
sphere. The same holds for another type of solution, the W-string.Comment: 13 pages, Latex, NIKHEF-H/94-02 (February 2, 1994), 1 figure
available by fax or mail (send request to [email protected]
Entropic-gravity derivation of MOND
A heuristic entropic-gravity derivation has previously been given of the
gravitational two-body force of modified Newtonian dynamics (MOND). Here, it is
shown that also another characteristic of MOND can be recovered, namely, the
external field effect (implying a violation of the Strong Equivalence
Principle). In fact, the derivation gives precisely the modified Poisson
equation which Bekenstein and Milgrom proposed as a consistent nonrelativistic
theory of MOND.Comment: 6 pages; v5: published versio
Entropic gravity, minimum temperature, and modified Newtonian dynamics
Verlinde's heuristic argument for the interpretation of the standard
Newtonian gravitational force as an entropic force is generalized by the
introduction of a minimum temperature (or maximum wave length) for the
microscopic degrees of freedom on the holographic screen. With the simplest
possible setup, the resulting gravitational acceleration felt by a test mass m
from a point mass M at a distance R is found to be of the form of the modified
Newtonian dynamics (MOND) as suggested by Milgrom. The corresponding MOND-type
acceleration constant is proportional to the minimum temperature, which can be
interpreted as the Unruh temperature of an emerging de-Sitter space. This
provides a possible explanation of the connection between local MOND-type
two-body systems and cosmology.Comment: 12 pages, v6: published versio
Osmotic pressure of matter and vacuum energy
The walls of the box which contains matter represent a membrane that allows
the relativistic quantum vacuum to pass but not matter. That is why the
pressure of matter in the box may be considered as the analog of the osmotic
pressure. However, we demonstrate that the osmotic pressure of matter is
modified due to interaction of matter with vacuum. This interaction induces the
nonzero negative vacuum pressure inside the box, as a result the measured
osmotic pressure becomes smaller than the matter pressure. As distinct from the
Casimir effect, this induced vacuum pressure is the bulk effect and does not
depend on the size of the box. This effect dominates in the thermodynamic limit
of the infinite volume of the box. Analog of this effect has been observed in
the dilute solution of 3He in liquid 4He, where the superfluid 4He plays the
role of the non-relativistic quantum vacuum, and 3He atoms play the role of
matter.Comment: 5 pages, 1 figure, JETP Lett. style, version accepted in JETP Letter
Towards a solution of the cosmological constant problem
The standard model of elementary particle physics and the theory of general
relativity can be extended by the introduction of a vacuum variable which is
responsible for the near vanishing of the present cosmological constant (vacuum
energy density). The explicit realization of this vacuum variable can be via a
three-form gauge field, an aether-type velocity field, or any other field
appropriate for the description of the equilibrium state corresponding to the
Lorentz-invariant quantum vacuum. The extended theory has, without fine-tuning,
a Minkowski-type solution of the field equations with spacetime-independent
fields and provides, therefore, a possible solution of the main cosmological
constant problem.Comment: 7 pages; v6: published versio
Newtonian gravity as an entropic force: Towards a derivation of G
It has been suggested that the Newtonian gravitational force may emerge as an
entropic force from a holographic microscopic theory. In this framework, the
possibility is reconsidered that Newton's gravitational coupling constant G can
be derived from the fundamental constants of the underlying microscopic theory.Comment: 10 pages. v6: published versio
Gluonic vacuum, q-theory, and the cosmological constant
In previous work, q-theory was introduced to describe the gravitating
macroscopic behavior of a conserved microscopic variable q. In this article,
the gluon condensate of quantum chromodynamics is considered in terms of
q-theory. The remnant vacuum energy density (i.e., cosmological constant) of an
expanding universe is estimated as K_{QCD}^3 / E_{Planck}^2, with string
tension K_{QCD} \approx (10^2 MeV)^2 and gravitational scale E_{Planck} \approx
10^{19} GeV. The only input for this estimate is general relativity, quantum
chromodynamics, and the Hubble expansion of the present Universe.Comment: 20 pages; v6: published versio
Spontaneous Breaking of Lorentz Invariance
We describe how a stable effective theory in which particles of the same
fermion number attract may spontaneously break Lorentz invariance by giving
non-zero fermion number density to the vacuum (and therefore dynamically
generating a chemical potential term). This mecanism yields a finite vacuum
expectation value could relate to work on signals of Lorentz violation
in electrodynamics.Comment: revtex4, 11 pages, 5 figures; v2:references added; v3:more references
added, typos fixed, some points in sect. IV clarified; v4:even more
references added, discussion in sect. V extended; v5:replaced to match
published version (minor corrections of form
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