182,698 research outputs found
Open/Closed String Topology and Moduli Space Actions via Open/Closed Hochschild Actions
In this paper we extend our correlation functions to the open/closed case.
This gives rise to actions of an open/closed version of the Sullivan PROP as
well as an action of the relevant moduli space. There are several unexpected
structures and conditions that arise in this extension which are forced upon us
by considering the open sector. For string topology type operations, one cannot
just consider graphs, but has to take punctures into account and one has to
restrict the underlying Frobenius algebras. In the moduli space, one first has
to pass to a smaller moduli space which is closed under open/closed duality and
then consider covers in order to account for the punctures
On the molecular mechanism of surface charge amplification and related phenomena at aqueous polyelectrolyte-graphene interfaces
In this communication we illustrate the occurrence of a recently reported new
phenomenon of surface-charge amplification, SCA, (originally dubbed
overcharging, OC), [Jimenez-Angeles F. and Lozada-Cassou M., J. Phys. Chem. B,
2004, 108, 7286] by means of molecular dynamics simulation of aqueous
electrolytes solutions involving multivalent cations in contact with charged
graphene walls and the presence of short-chain lithium polystyrene sulfonates
where the solvent water is described explicitly with a realistic molecular
model. We show that the occurrence of SCA in these systems, in contrast to that
observed in primitive models, involves neither contact co-adsorption of the
negatively charged macroions nor divalent cations with a large size and charge
asymmetry as required in the case of implicit solvents. In fact the SCA
phenomenon hinges around the preferential adsorption of water (over the
hydrated ions) with an average dipolar orientation such that the charges of the
water's hydrogen and oxygen sites induce magnification rather than screening of
the positive-charged graphene surface, within a limited range of surface-charge
density.Comment: 10 pages, 6 figure
Formation of charge and spin ordering in strongly correlated electron systems
In this review we present results of our theoretical study of charge and spin
ordering in strongly correlated electron systems obtained within various
generalizations of the Falicov-Kimball model. The primary goal of this study
was to identify crucial interactions that lead to the stabilization of various
types of charge ordering in these systems, like the axial striped ordering,
diagonal striped ordering, phase-separated ordering, phase-segregated ordering,
etc. Among the major interactions that come into account, we have examined the
effect of local Coulomb interaction between localized and itinerant electrons,
long-range and correlated hopping of itinerant electrons, long-range Coulomb
interaction between localized and itinerant electrons, local Coulomb
interaction between itinerant electrons, local Coulomb interaction between
localized electrons, spin-dependent interaction between localized and itinerant
electrons, both for zero and nonzero temperatures, as well as for doped and
undoped systems. Finally, the relevance of resultant solutions for a
description of rare-earth and transition-metal compounds is discussed.Comment: 66 pages, 65 figure
Disorder effects on the static scattering function of star branched polymers
We present an analysis of the impact of structural disorder on the static
scattering function of f-armed star branched polymers in d dimensions. To this
end, we consider the model of a star polymer immersed in a good solvent in the
presence of structural defects, correlated at large distances r according to a
power law \sim r^{-a}. In particular, we are interested in the ratio g(f) of
the radii of gyration of star and linear polymers of the same molecular weight,
which is a universal experimentally measurable quantity. We apply a direct
polymer renormalization approach and evaluate the results within the double
\varepsilon=4-d, \delta=4-a-expansion. We find an increase of g(f) with an
increasing \delta. Therefore, an increase of disorder correlations leads to an
increase of the size measure of a star relative to linear polymers of the same
molecular weight.Comment: 17 pages, 7 figure
Mechanism of collisionless sound damping in dilute Bose gas with condensate
We develop a microscopic theory of sound damping due to Landau mechanism in
dilute gas with Bose condensate. It is based on the coupled evolution equations
of the parameters describing the system. These equations have been derived in
earlier works within a microscopic approach which employs the
Peletminskii-Yatsenko reduced description method for quantum many-particle
systems and Bogoliubov model for a weakly nonideal Bose gas with a separated
condensate. The dispersion equations for sound oscillations were obtained by
linearization of the mentioned evolution equations in the collisionless
approximation. They were analyzed both analytically and numerically. The
expressions for sound speed and decrement rate were obtained in high and low
temperature limiting cases. We have shown that at low temperature the
dependence of the obtained quantities on temperature significantly differs from
those obtained by other authors in the semi-phenomenological approaches.
Possible effects connected with non-analytic temperature dependence of
dispersion characteristics of the system were also indicated.Comment: 17 pages, 7 figure
Comparison of polarization switching in ferroelectric TGS and relaxor SBN crystals
The comparative experimental analysis of polarization reversal kinetics in
conventional homogeneous triglycine sulfate ((NH_{2}CH_{2}COOH)_{3} \cdot
H_{2}SO_{4}; TGS) and relaxor strontium barium niobate
(Sr_{0.61}Ba_{0.39}Nb_{2}O_{6}; SBN) crystals have been performed in a broad
range of measurement conditions. The experimental data have been collected from
microscopic observation of the domain structure, switching current and D-E
hysteresis loop registration. The hysteresis loop and dielectric spectra have a
strong link to the configuration of ferroelectric microdomains. The domain
structure dynamics was examined by the nematic liquid crystal (NLC) method.Comment: 6 pages, 6 figure
Jordan-Schwinger Representations and Factorised Yang-Baxter Operators
The construction elements of the factorised form of the Yang-Baxter R
operator acting on generic representations of q-deformed sl(n+1) are studied.
We rely on the iterative construction of such representations by the restricted
class of Jordan-Schwinger representations. The latter are formulated
explicitly. On this basis the parameter exchange and intertwining operators are
derived.Comment: based on a contribution to ISQS200
Werner's Measure on Self-Avoiding Loops and Welding
Werner's conformally invariant family of measures on self-avoiding loops on
Riemann surfaces is determined by a single measure on self-avoiding
loops in which surround . Our first major
objective is to show that the measure is infinitesimally invariant with
respect to conformal vector fields (essentially the Virasoro algebra of
conformal field theory). This makes essential use of classical variational
formulas of Duren and Schiffer, which we recast in representation theoretic
terms for efficient computation. We secondly show how these formulas can be
used to calculate (in principle, and sometimes explicitly) quantities (such as
moments for coefficients of univalent functions) associated to the conformal
welding for a self-avoiding loop. This gives an alternate proof of the
uniqueness of Werner's measure. We also attempt to use these variational
formulas to derive a differential equation for the (Laplace transform of) the
"diagonal distribution" for the conformal welding associated to a loop; this
generalizes in a suggestive way to a deformation of Werner's measure
conjectured to exist by Kontsevich and Suhov (a basic inspiration for this
paper)
Intertwinors on Functions over the Product of Spheres
We give explicit formulas for the intertwinors on the scalar functions over
the product of spheres with the natural pseudo-Riemannian product metric using
the spectrum generating technique. As a consequence, this provides another
proof of the even order conformally invariant differential operator formulas
obtained earlier by T. Branson and the present author
Quantum Integrable Model of an Arrangement of Hyperplanes
The goal of this paper is to give a geometric construction of the Bethe
algebra (of Hamiltonians) of a Gaudin model associated to a simple Lie algebra.
More precisely, in this paper a quantum integrable model is assigned to a
weighted arrangement of affine hyperplanes. We show (under certain assumptions)
that the algebra of Hamiltonians of the model is isomorphic to the algebra of
functions on the critical set of the corresponding master function. For a
discriminantal arrangement we show (under certain assumptions) that the
symmetric part of the algebra of Hamiltonians is isomorphic to the Bethe
algebra of the corresponding Gaudin model. It is expected that this
correspondence holds in general (without the assumptions). As a byproduct of
constructions we show that in a Gaudin model (associated to an arbitrary simple
Lie algebra), the Bethe vector, corresponding to an isolated critical point of
the master function, is nonzero
- …