12,697 research outputs found
Effective Superpotentials for SO/Sp with Flavor from Matrix Models
We study matrix models related to gauge theories with flavors. We
give the effective superpotentials for gauge theories with arbitrary tree level
superpotential up to first instanton level. For quartic tree level
superpotential we obtained exact one-cut solution. We also derive
Seiberg-Witten curve for these gauge theories from matrix model argument.Comment: 17pp,2 figures, v2;refs added and to appear in MPL
Phase Diagram of a Classical Fluid in a Quenched Random Potential
We consider the phase diagram of a classical fluid in the presence of a
random pinning potential of arbitrary strength. Introducing replicas for
averaging over the quenched disorder, we use the hypernetted chain
approximation to calculate the correlations in the replicated liquid. The
freezing transition of the liquid into a nearly crystalline state is studied
using a density functional approach, and the liquid-to-glass transition is
studied using a phenomenological replica symmetry breaking approach introduced
by Mezard and Parisi. The first-order liquid-to-crystal transition is found to
change to a continuous liquid-to-glass transition as the strength of the
disorder is increased above a threshold value.Comment: 7 pages, 4 figures, to appear in EuroPhysics Letter
Origin of Ferromagnetism and its pressure and doping dependence in TlMnO
Using NMTO-{\it downfolding} technique, we explore and establish the origin
of ferromagnetism in the pyrochlore system, TlMnO. It is
found to be driven by hybridization induced spin-polarization of the
delocalized charge carriers derived from Tl- and O- states. The
mean-field estimate of the ferromagnetic transition temperature, T,
estimated using computed exchange integrals are found to be in good agreement
with the measurements. We find an enhancement of T for moderate doping
with nonmagnetic Sb and a suppression of T upon application of pressure,
both in agreement with experimental findings.Comment: Accepted for publication in PR
Fusion and breakup in the reactions of 6,7Li and 9Be
We develop a three body classical trajectory Monte Carlo (CTMC) method to
dicsuss the effect of the breakup process on heavy-ion fusion reactions induced
by weakly bound nuclei. This method follows the classical trajectories of
breakup fragments after the breakup takes place, and thus provides an
unambiguous separation between complete and incomplete fusion cross sections.
Applying this method to the fusion reaction Li + Bi, we find that
there is a significant contribution to the total complete fusion cross sections
from the process where all the breakup fragments are captured by the target
nucleus (i.e., the breakup followed by complete fusion).Comment: 4 pages, 3 eps figures. Uses espcrc1.sty. To be published in the
proceedings of the 8th international conference on clustering aspects of
nuclear structure and dynamics, November 24 - 29, 2003, Nara, Japan (Nucl.
Phys. A
Growth mechanism of nanocrystals in solution: ZnO, a case study
We investigate the mechanism of growth of nanocrystals from solution using
the case of ZnO. Spanning a wide range of values of the parameters, such as the
temperature and the reactant concentration, that control the growth, our
results establish a qualitative departure from the widely accepted diffusion
controlled coarsening (Ostwald ripening) process quantified in terms of the
Lifshitz-Slyozov-Wagner theory. Further, we show that these experimental
observations can be qualitatively and quantitatively understood within a growth
mechanism that is intermediate between the two well-defined limits of diffusion
control and kinetic control.Comment: 10 pages, 4 figure
Quiver Gauge Theory of Nonabelian Vortices and Noncommutative Instantons in Higher Dimensions
We construct explicit BPS and non-BPS solutions of the Yang-Mills equations
on the noncommutative space R^{2n}_\theta x S^2 which have manifest spherical
symmetry. Using SU(2)-equivariant dimensional reduction techniques, we show
that the solutions imply an equivalence between instantons on R^{2n}_\theta x
S^2 and nonabelian vortices on R^{2n}_\theta, which can be interpreted as a
blowing-up of a chain of D0-branes on R^{2n}_\theta into a chain of spherical
D2-branes on R^{2n} x S^2. The low-energy dynamics of these configurations is
described by a quiver gauge theory which can be formulated in terms of new
geometrical objects generalizing superconnections. This formalism enables the
explicit assignment of D0-brane charges in equivariant K-theory to the
instanton solutions.Comment: 45 pages, 4 figures; v2: minor correction
NiS - An unusual self-doped, nearly compensated antiferromagnetic metal
NiS, exhibiting a text-book example of a first-order transition with many
unusual properties at low temperatures, has been variously described in terms
of conflicting descriptions of its ground state during the past several
decades. We calculate these physical properties within first-principle
approaches based on the density functional theory and conclusively establish
that all experimental data can be understood in terms of a rather unusual
ground state of NiS that is best described as a self-doped, nearly compensated,
antiferromagnetic metal, resolving the age-old controversy. We trace the origin
of this novel ground state to the specific details of the crystal structure,
band dispersions and a sizable Coulomb interaction strength that is still
sub-critical to drive the system in to an insulating state. We also show how
the specific antiferromagnetic structure is a consequence of the less-discussed
90 degree and less than 90 degree superexchange interactions built in to such
crystal structures
Reconstruction of supernova {\nu}_{\mu}, {\nu}_{\tau}, anti-{\nu}_{\mu}, and anti-{\nu}_{\tau} neutrino spectra at scintillator detectors
We present a new technique to directly reconstruct the spectra of mu/tau
neutrinos and antineutrinos from a supernova, using neutrino-proton elastic
scattering events (nu+p to nu+p) at scintillator detectors. These neutrinos,
unlike electron neutrinos and antineutrinos, have only neutral current
interactions, which makes it very challenging, with any reaction, to detect
them and measure their energies. With updated inputs from theory and
experiments, we show that this channel provides a robust and sensitive measure
of their spectra. Given the low yields and lack of spectral information in
other neutral current channels, this is perhaps the only realistic way to
extract such information. This will be indispensable for understanding flavor
oscillations of SN neutrinos, as it is likely to be impossible to disentangle
neutrino mixing from astrophysical uncertainties in a SN without adequate
spectral coverage of all flavors. We emphasize that scintillator detectors,
e.g., Borexino, KamLAND, and SNO+, have the capability to observe these events,
but they must be adequately prepared with a trigger for a burst of low-energy
events. We also highlight the capabilities of a larger detector like LENA.Comment: v3: Typo corrected in Eq.14, and metadata edits. Matches PRD version.
14 pages, 9 figures, 1 tabl
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