427,537 research outputs found
Nonsingular density profiles of dark matter halos and Strong gravitational lensing
We use the statistics of strong gravitational lenses to investigate whether
mass profiles with a flat density core are supported. The probability for
lensing by halos modeled by a nonsingular truncated isothermal sphere (NTIS)
with image separations greater than a certain value (ranging from zero to ten
arcseconds) is calculated. NTIS is an analytical model for the postcollapse
equilibrium structure of virialized objects derived by Shapiro, Iliev & Raga.
This profile has a soft core and matches quite well with the mass profiles of
dark matter-dominated dwarf galaxies deduced from their observed rotation
curves. It also agrees well with the NFW (Navarro-Frenk-White) profile at all
radii outside of a few NTIS core radii. Unfortunately, comparing the results
with those for singular lensing halos (NFW and SIS+NFW) and strong lensing
observations, the probabilities for lensing by NTIS halos are far too low. As
this result is valid for any other nonsingular density profiles (with a large
core radius), we conclude that nonsingular density profiles (with a large core
radius) for CDM halos are ruled out by statistics of strong gravitational
lenses.Comment: 17 pages, 4 figures, ApJ accepted. Final version matches the proofs.
A curve in figure 2 is corrected, conclusions unchange
Supercurrent conservation in the lattice Wess-Zumino model with Ginsparg-Wilson fermions
We study supercurrent conservation for the four-dimensional Wess-Zumino model
formulated on the lattice. The formulation is one that has been discussed
several times, and uses Ginsparg-Wilson fermions of the overlap (Neuberger)
variety, together with an auxiliary fermion (plus superpartners), such that a
lattice version of U(1)_R symmetry is exactly preserved in the limit of
vanishing bare mass. We show that the almost naive supercurrent is conserved at
one loop. By contrast we find that this is not true for Wilson fermions and a
canonical scalar action. We provide nonperturbative evidence for the
nonconservation of the supercurrent in Monte Carlo simulations.Comment: 19 pages, 5 figure
Recommended from our members
"Mirror Image" space charge distribution in XLPE power cable under opposite stressing voltage polarity
The paper presents the research on space charge distribution under different polarities in full size cross-linked polyethylene power cables using the pulsed electro-acoustic technique. Under both positive and negative voltage space charge distributions possess about the same profiles but opposite polarities. Similar phenomenon had been reported previously in plaque samples and was termed as “mirror image effect”. By comparing the results among the cables treated (degassing) under different conditions, the paper concludes that the “mirror image” charge distribution is mainly attributed to bulk effect within the volume of the insulation, whilst the electron transfer by tunnelling through an electrode/insulator interface contribute to the generation of homo “mirror image” at the vicinity of the electrode
Characterization of the 4-canonical birationality of algebraic threefolds
In this article we present a 3-dimensional analogue of a well-known theorem
of E. Bombieri (in 1973) which characterizes the bi-canonical birationality of
surfaces of general type. Let be a projective minimal 3-fold of general
type with -factorial terminal singularities and the geometric genus
. We show that the 4-canonical map is {\it not}
birational onto its image if and only if is birationally fibred by a family
of irreducible curves of geometric genus 2 with
where is a general irreducible member in .Comment: 25 pages, to appear in Mathematische Zeitschrif
Non-analyticity of the groud state energy of the Hamiltonian for Hydrogen atom in non-relativistic QED
We derive the ground state energy up to the fourth order in the fine
structure constant for the translation invariant Pauli-Fierz
Hamiltonian for a spinless electron coupled to the quantized radiation field.
As a consequence, we obtain the non-analyticity of the ground state energy of
the Pauli-Fierz operator for a single particle in the Coulomb field of a
nucleus
- …