15,011 research outputs found
Study on the morphometric and meristic characteristics of splendid silver belly Leiognathus splendens (Cuvier) from Bombay coast
Ten morphometric and six meristic characters of Leiognathus splendens (Cuvier) of Bombay Coast have been studied sexwise. Regression and sexwise difference if any between the compared morphometric characteristics have been worked out. Range, mode, standard deviation, co-efficient of variation of 6 meristic characters have been analysed. There was no significant difference between the sexes in morphometric and any deviation in the meristic characters
Superconformal field theories from crystal lattices
We propose a brane configuration for the (2+1)d,
superconformal theories (CFT) arising from M2-branes probing toric
Calabi-Yau 4-fold cones, using a T-duality transformation of M-theory. We
obtain intersections of M5-branes on a three-torus which form a 3d bipartite
crystal lattice in a way similar to the 2d dimer models for CFT. The
fundamental fields of the CFT are M2-brane discs localized around the
intersections, and the super-potential terms are identified with the atoms of
the crystal. The model correctly reproduces the complete BPS spectrum of mesons
and baryons.Comment: 4 pages, 4 figures, revtex; v2. references added, minor correction
Phase transition and hybrid star in a SU(2) chiral sigma model
We use a modified SU(2) chiral sigma model to study nuclear matter at high
density using mean field approach. We also study the phase transition of
nuclear matter to quark matter in the interior of highly dense neutron stars.
Stable solutions of Tolman-Oppenheimer-Volkoff equations representing hybrid
stars are obtained with a maximum mass of 1.69 , radii around 9.3
kms and a quark matter core constituting nearly 55-85 % of the star radii.Comment: 19 pages, 9 figures, accepted for Mod. Phys. Letts.
Phase Transition and Hybrid Star in a Nonlinear model
The phase transition between the nuclear matter and the quark matter is
examined. The relativistic mean field theory(RMF) is consider with interacting
nucleons and mesons using TM1 parameter set for the nuclear matter equations of
state. It is found that the trasition point depends on coupling constant
and bag pressure. From the study of the structure of a hybrid
neutron star, it is observed that the star contains quark matter in the
interior and neutron matter on the outer perifery.Comment: 8 pages, 7 figures, to appear in Int. J. Mod. Phy.
Heterotic strings on G_2 orbifolds
We study compactification of heterotic strings to three dimensions on
orbifolds of G_2 holonomy. We consider the standard embedding and show that the
gauge group is broken from E_8 x E_8 or SO(32) to F_4 x E_8 or SO(25)
respectively. We also compute the spectrum of massless states and compare with
the results obtained from reduction of the 10-dimensional fields. Non-standard
embeddings are discussed briefly. For type II compactifications we verify that
IIB and IIA have equal massless spectrum.Comment: LaTex, 21 page
Superconductors from Superstrings
We establish that in a large class of strongly coupled 3+1 dimensional N=1
quiver conformal field theories with gravity duals, adding a chemical potential
for the R-charge leads to the existence of superfluid states in which a chiral
primary operator of the schematic form O = \lambda\lambda + W condenses. Here
\lambda is a gluino and W is the superpotential. Our argument is based on the
construction of a consistent truncation of type IIB supergravity that includes
a U(1) gauge field and a complex scalar.Comment: 5 pages, 2 figures; v2 improved figure, small change
Self-energies in itinerant magnets: A focus on Fe and Ni
We present a detailed study of local and non-local correlations in the
electronic structure of elemental transition metals carried out by means of the
Quasiparticle Self-consistent GW (QSGW ) and Dynamical Mean Field Theory
(DMFT). Recent high resolution ARPES and Haas-van Alphen data of two typical
transition metal systems (Fe and Ni) are used as case study. (i) We find that
the properties of Fe are very well described by QSGW. Agreement with cyclotron
and very clean ARPES measurements is excellent, provided that final-state
scattering is taken into account. This establishes the exceptional reliability
of QSGW also in metallic systems. (ii) Nonetheless QSGW alone is not able to
provide an adequate description of the Ni ARPES data due to strong local spin
fluctuations. We surmount this deficiency by combining nonlocal charge
fluctuations in QSGW with local spin fluctuations in DMFT (QSGW + 'Magnetic
DMFT'). (iii) Finally we show that the dynamics of the local fluctuations are
actually not crucial. The addition of an external static field can lead to
similarly good results if non-local correlations are included through QSGW
G(2) quivers
We present, in explicit matrix representation and a modernity befitting the community, the classification of the finite discrete subgroups of G2 and compute the McKay quivers arising therefrom. Of physical interest are the classes of Script N = 1 gauge theories descending from M-theory and of mathematical interest are possible steps toward a systematic study of crepant resolutions to smooth G2 manifolds as well as generalised McKay Correspondences. This writing is a companion monograph to hep-th/9811183 and hep-th/9905212, wherein the analogues for Calabi-Yau three- and four-folds were considered
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