17,482 research outputs found
Alignment and morphology of elliptical galaxies: the influence of the cluster tidal field
We investigate two possible effects of the tidal field induced by a spherical
cluster on its elliptical galaxy members: the modification of the ellipticity
of a spherical galaxy and the isophotal alignment in the cluster radial
direction of a misaligned prolate galaxy. Numerical N-body simulations have
been performed for radial and circular galactic orbits. The properties of the
stars' zero--velocity surfaces in the perturbed galaxies are explored briefly,
and the adiabaticity of the galaxy to the external field is discussed. For a
choice of parameters characteristic of rich clusters we find that the induced
ellipticity on a spherical galaxy is below or close to the detectability level.
But we find that the tidal torque can result in significant isophotal alignment
of the galaxies' major axis with the cluster radial direction if the galaxy is
outside the cluster core radius. The time required for the alignment is very
short compared with the Hubble time. A significant increase in the ellipticity
of the outer isophotes of the prolate model is also found, but with no
observable isophotal twisting. Our main prediction is an alignment segregation
of the elliptical galaxy population according to whether their orbits lie
mostly outside or inside the cluster core radius. These results also suggest
that galactic alignment in rich clusters is not incompatible with a bottom-up
galaxy formation scenario.Comment: 20 pages, uuencoded compressed tarred postscrip
Leptoquark explanation of HERA anomaly in the context of gauge unification
We examine the consequences of leptoquark explanation of HERA anomaly in the
context of R parity conserving supersymmetric gauge unified theory with the
gauge unification scale at GeV. We pointed out the difficulty of
constructing a grandunified theory. However gauge unification is still possible
at GeV when additional multiplets are introduced. We determine
the mass spectrum of these additional fields (fermions and scalars) in gauge
mediated and supergravity scenarios. Unique signatures and mass bounds are
discussed.Comment: 19 pages(Latex), 1 PS Figur
Effect of external electric field on the charge density waves in one dimensional Hubbard superlattices
We have studied the ground state of the one dimensional Hubbard superlattice
structures with different unit cell sizes in the presence of electric field.
Self consistent Hartree-Fock approximation calculation is done in the weak to
intermediate interaction regime. Studying the charge gap at the Fermi level and
the charge density structure factor, we get an idea how the charge modulation
on the superlattice is governed by the competition between the electronic
correlation and the external electric field.Comment: 6 pages, 8 figures. accepted in Journal of Physics: Condensed Matte
A Theory of Anomaly With Right-Handed Currents
We present an ultraviolet complete theory for the and anomaly
in terms of a low mass gauge boson of a class of left-right symmetric
models. These models, which are based on the gauge symmetry , utilize vector-like fermions to
generate quark and lepton masses via a universal seesaw mechanism. A parity
symmetric version as well as an asymmetric version are studied. A light sterile
neutrino emerges naturally in this setup, which allows for new decay modes of
-meson via right-handed currents. We show that these models can explain
and anomaly while being consistent with LHC and LEP data as
well as low energy flavor constraints arising from , mixing, etc., but only for a limited range
of the mass: for
parity asymmetric (symmetric) Yukawa sectors. The light sterile neutrinos
predicted by the model may be relevant for explaining the MiniBoone and LSND
neutrino oscillation results. The parity symmetric version of the model
provides a simple solution to the strong CP problem without relying on the
axion. It also predicts an isospin singlet top partner with a mass TeV.Comment: 43 pages, 7 figures, references added, model slightly modifie
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