2,020,994 research outputs found
Two-point correlation function in systems with van der Waals type interaction
The behavior of the bulk two-point correlation function in
-dimensional system with van der Waals type interactions is investigated and
its consequences on the finite-size scaling properties of the susceptibility in
such finite systems with periodic boundary conditions is discussed within
mean-spherical model which is an example of Ornstein and Zernike type theory.
The interaction is supposed to decay at large distances as
, with , and . It is shown
that decays as for , exponentially
for , where , and again in a power
law as for . The analytical form of the
leading-order scaling function of in any of these regimes is
derived.Comment: 12 pages, 3 figures, revtex. Two references added To be published in
EPJ
Lightlike Brane as a Gravitational Source of Misner-Wheeler-Type Wormhole
Consistent Lagrangian description of lightlike p-branes (LL-branes) is
presented in two equivalent forms - a Polyakov-type formulation and a dual to
it Nambu-Goto-type formulation. An important characteristic feature of the
LL-branes is that the brane tension appears as a non-trivial additional
dynamical degree of freedom. Next, properties of p=2 LL-brane dynamics (as a
test brane) in D=4 Kerr or Kerr-Newman gravitational backgrounds are discussed
in some detail. It is shown that the LL-brane automatically positions itself on
the horizon and rotates along with the same angular velocity. Finally, a
Misner-Wheeler-type of Reissner-Nordstroem wormhole is constructed in a
self-consistent electrically sourceless Einstein-Maxwell system in the D=4 bulk
interacting with a LL-brane. The pertinent wormhole throat is located precisely
at the LL-brane sitting on the outer Reissner-Nordstroem horizon with the
Reissner-Nordstroem mass and charge being functions of the dynamical LL-brane
tension.Comment: improved derivation in section 4; additional comment in conclusions;
results unchange
Ion radial diffusion in an electrostatic impulse model for stormtime ring current formation
Guiding-center simulations of stormtime transport of ring-current and radiation-belt ions having first adiabatic invariants mu is approximately greater than 15 MeV/G (E is approximately greater than 165 keV at L is approximately 3) are surprisingly well described (typically within a factor of approximately less than 4) by the quasilinear theory of radial diffusion. This holds even for the case of an individual model storm characterized by substorm-associated impulses in the convection electric field, provided that the actual spectrum of the electric field is incorporated in the quasilinear theory. Correction of the quasilinear diffusion coefficient D(sub LL)(sup ql) for drift-resonance broadening (so as to define D(sub LL)(sup ql)) reduced the typical discrepancy with the diffusion coefficients D(sub LL)(sup sim) deduced from guiding-center simulations of representative-particle trajectories to a factor of approximately 3. The typical discrepancy was reduced to a factor of approximately 1.4 by averaging D(sub LL)(sup sim), D(sub LL)(sup ql), and D(sub LL)(sup rb) over an ensemble of model storms characterized by different (but statistically equivalent) sets of substorm-onset times
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