1,488 research outputs found
Nuclear incompressibility in the quasilocal density functional theory
We explore the ability of the recently established quasilocal density
functional theory for describing the isoscalar giant monopole resonance. Within
this theory we use the scaling approach and perform constrained calculations
for obtaining the cubic and inverse energy weighted moments (sum rules) of the
RPA strength. The meaning of the sum rule approach in this case is discussed.
Numerical calculations are carried out using Gogny forces and an excellent
agreement is found with HF + RPA results previously reported in literature. The
nuclear matter compression modulus predicted in our model lies in the range
210-230 MeV which agrees with earlier findings. The information provided by the
sum rule approach in the case of nuclei near the neutron drip line is also
discussed.Comment: 10 pages, LaTe
Approximating Turaev-Viro 3-manifold invariants is universal for quantum computation
The Turaev-Viro invariants are scalar topological invariants of compact,
orientable 3-manifolds. We give a quantum algorithm for additively
approximating Turaev-Viro invariants of a manifold presented by a Heegaard
splitting. The algorithm is motivated by the relationship between topological
quantum computers and (2+1)-D topological quantum field theories. Its accuracy
is shown to be nontrivial, as the same algorithm, after efficient classical
preprocessing, can solve any problem efficiently decidable by a quantum
computer. Thus approximating certain Turaev-Viro invariants of manifolds
presented by Heegaard splittings is a universal problem for quantum
computation. This establishes a novel relation between the task of
distinguishing non-homeomorphic 3-manifolds and the power of a general quantum
computer.Comment: 4 pages, 3 figure
Antiproton-deuteron annihilation at low energies
Recent experimental studies of the antiproton-deuteron system at low energies
have shown that the imaginary part of the antiproton-deuteron scattering length
is smaller than the antiproton-proton one. Two- and three-body systems with
strong annihilation are investigated and a mechanism explaining this unexpected
relation between the imaginary parts of the scattering lengths is proposed.Comment: 6 pages, 3 figures, to be published in The European Physical Journal
A central extension of \cD Y_{\hbar}(\gtgl_2) and its vertex representations
A central extension of \cD Y_{\hbar}(\gtgl_2) is proposed. The bosonization
of level module and vertex operators are also given.Comment: 10 pages, AmsLatex, to appear in Lett. in Math. Phy
Orbital order and ferrimagnetic properties of the new compound
By means of the LSDA+U method and the Green function method, we investigate
the electronic and magnetic properties of the new material of
SrCaReCuO. Our LSDA+U calculation shows that this system is
an insulator with a net magnetic moment of 1.01 /f.u., which is in
good agreement with the experiment. Magnetic moments are mainly located at Cu
atoms, and the magnetic moments of neighboring Cu sites align anti-parallel. It
is the non-magnetic Re atoms that induce an orbital order of electrons of
Cu atoms, which is responsible for the strong exchange interaction and the high
magnetic transition temperature. Based on the LSDA+U results, we introduce an
effective model for the spin degrees of freedom, and investigate the
finite-temperature properties by the Green function method. The obtained
results are consistent with the experimental results, indicating that the
spin-alternating Heisenberg model is suitable for this compound.Comment: 8 pages and 5 figur
Permanent current from non-commutative spin algebra
We show that a spontaneous electric current is induced in a nano-scale
conducting ring just by putting three ferromagnets. The current is a direct
consequence of the non-commutativity of the spin algebra, and is proportional
to the non-coplanarity (chirality) of the magnetization vectors. The
spontaneous current gives a natural explanation to the chirality-driven
anomalous Hall effect.Comment: 7 pages, 4 figures on separate pag
Geometry of q-Hypergeometric Functions as a Bridge between Yangians and Quantum Affine Algebras
The rational quantized Knizhnik-Zamolodchikov equation (qKZ equation)
associated with the Lie algebra is a system of linear difference
equations with values in a tensor product of Verma modules. We solve the
equation in terms of multidimensional -hypergeometric functions and define a
natural isomorphism between the space of solutions and the tensor product of
the corresponding quantum group Verma modules, where the parameter
is related to the step of the qKZ equation via .
We construct asymptotic solutions associated with suitable asymptotic zones
and compute the transition functions between the asymptotic solutions in terms
of the trigonometric -matrices. This description of the transition functions
gives a new connection between representation theories of Yangians and quantum
loop algebras and is analogous to the Kohno-Drinfeld theorem on the monodromy
group of the differential Knizhnik-Zamolodchikov equation.
In order to establish these results we construct a discrete Gauss-Manin
connection, in particular, a suitable discrete local system, discrete homology
and cohomology groups with coefficients in this local system, and identify an
associated difference equation with the qKZ equation.Comment: 66 pages, amstex.tex (ver. 2.1) and amssym.tex are required;
misprints are correcte
Antiprotons Annihilation in the Galaxy As A Source of Diffuse Gamma Background
The existence of antimatter domains in baryon asymmetrical Universe can
appear as the cosmological consequence of particle theory in inflationary
models with non-homogeneous baryosynthesis. Such a domain can survive in the
early Universe and form globular cluster of antimatter stars in our Galaxy. The
model of antimatter pollution of Galaxy and annihilation with matter gas is
developed. The proton-antiproton annihilation gamma flux is shown to reproduce
the observed galactic gamma background measured by EGRET. From comparison with
observational data the estimation on the maximally allowed amount of antimatter
stars, possibly present in our Galaxy, is found.Comment: LaTeX2e, 18 pages, 3 PostScript figures. Submitted to Yad.Fi
On Bohr-Sommerfeld bases
This paper combines algebraic and Lagrangian geometry to construct a special
basis in every space of conformal blocks, the Bohr-Sommerfeld (BS) basis. We
use the method of [D. Borthwick, T. Paul and A. Uribe, Legendrian distributions
with applications to the non-vanishing of Poincar\'e series of large weight,
Invent. math, 122 (1995), 359-402, preprint hep-th/9406036], whereby every
vector of a BS basis is defined by some half-weighted Legendrian distribution
coming from a Bohr-Sommerfeld fibre of a real polarization of the underlying
symplectic manifold. The advantage of BS bases (compared to bases of theta
functions in [A. Tyurin, Quantization and ``theta functions'', Jussieu preprint
216 (Apr 1999), e-print math.AG/9904046, 32pp.]) is that we can use information
from the skillful analysis of the asymptotics of quantum states. This gives
that Bohr-Sommerfeld bases are unitary quasi-classically. Thus we can apply
these bases to compare the Hitchin connection with the KZ connection defined by
the monodromy of the Knizhnik-Zamolodchikov equation in combinatorial theory
(see, for example, [T. Kohno, Topological invariants for 3-manifolds using
representations of mapping class group I, Topology 31 (1992), 203-230; II,
Contemp. math 175} (1994), 193-217]).Comment: 43 pages, uses: latex2e with amsmath,amsfonts,theore
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