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 $\sim 10^{16}$ GeV. We pointed out the difficulty of constructing a grandunified theory. However gauge unification is still possible at $\sim 10^{16}$ 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 R(D∗,D)R(D^*,D) Anomaly With Right-Handed Currents

We present an ultraviolet complete theory for the $R(D^*)$ and $R(D)$ anomaly in terms of a low mass $W_R^\pm$ gauge boson of a class of left-right symmetric models. These models, which are based on the gauge symmetry $SU(3)_c \times SU(2)_L \times SU(2)_R \times U(1)_{B-L}$, 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 $B$-meson via right-handed currents. We show that these models can explain $R(D^*)$ and $R(D)$ anomaly while being consistent with LHC and LEP data as well as low energy flavor constraints arising from $K_L-K_S, B_{d,s}-\bar{B}_{d,s}$, $D-\bar{D}$ mixing, etc., but only for a limited range of the $W_R$ mass: $1.2\, (1.8)~{\rm TeV} \leq M_{W_R}\leq 3~ {\rm TeV}$ 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 $M_T = (1.5-2.5)$ TeV.Comment: 43 pages, 7 figures, references added, model slightly modifie