1,370 research outputs found
Hilbert Schemes, Separated Variables, and D-Branes
We explain Sklyanin's separation of variables in geometrical terms and
construct it for Hitchin and Mukai integrable systems. We construct Hilbert
schemes of points on for \Sigma = {\IC}, {\IC}^{*} or elliptic
curve, and on and show that their complex deformations
are integrable systems of Calogero-Sutherland-Moser type. We present the
hyperk\"ahler quotient constructions for Hilbert schemes of points on cotangent
bundles to the higher genus curves, utilizing the results of Hurtubise,
Kronheimer and Nakajima. Finally we discuss the connections to physics of
-branes and string duality.Comment: harvmac, 27 pp. big mode; v2. typos and references correcte
Electronic Structure of New LiFeAs High-Tc Superconductor
We present results of it ab initio LDA calculations of electronic structure
of "next generation" layered ironpnictide High-Tc superconductor LiFeAs
(Tc=18K). Obtained electronic structure of LiFeAs is very similar to recently
studied ReOFeAs (Re=La,Ce,Pr,Nd,Sm) and AFe2As2 (A=Ba,Sr) compounds. Namely
close to the Fermi level its electronic properties are also determined ma inly
by Fe 3d-orbitals of FeAs4 two-dimensional layers. Band dispersions of LiFeAs
are very similar to the LaOFeAs and BaFe2As2 systems as well as the shape of
the Fe-3d density o f states and Fermi surface.Comment: 4 pages, 5 figures; Electronic structure improved with respect to new
experimental crystal structure dat
Duality in Integrable Systems and Gauge Theories
We discuss various dualities, relating integrable systems and show that these
dualities are explained in the framework of Hamiltonian and Poisson reductions.
The dualities we study shed some light on the known integrable systems as well
as allow to construct new ones, double elliptic among them. We also discuss
applications to the (supersymmetric) gauge theories in various dimensions.Comment: harvmac 45 pp.; v4. minor corrections, to appear in JHE
Electronic Structure of New AFFeAs Prototype of Iron Arsenide Superconductors
This work is provoked by recent discovery of new class prototype systems
AFFeAs (A=Sr,Ca) of novel layered ironpnictide High-Tc superconductors
(Tc=36K). Here we report ab initio LDA results for electronic structure of the
AFFeAs systems. We provide detailed comparison between electronic properties of
both new systems and reference LaOFeAs (La111) compound. In the vicinity of the
Fermi level all three systems have essentially the same band dispersions.
However for iron fluoride systems F(2p) states were found to be separated in
energy from As(4p) ones in contrast to La111, where O(2p) states strongly
overlaps with As(4p). Thus it should be more plausible to include only Fe(3d)
and As(4p) orbitals into a realistic noninteracting model than for La111.
Moreover Sr substitution with smaller ionic radius Ca in AFFeAs materials leads
to a lattice contruction and stronger Fe(3d)-As(4p) hybridization resulting in
smaller value of the density of states at the Fermi level in the case of Ca
compound. So to some extend Ca system reminds RE111 with later Rare Earths.
However Fermi surface of new fluorides is found to be nearly perfect
two-dimensional. Also we do not expect strong dependence of superconducting
properties with respect to different types of A substitutes.Comment: 5 pages, 4 figure
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