301 research outputs found
Density matrix renormalization group for the Berezinskii-Kosterlitz-Thouless transition of the 19-vertex model
We embody the density matrix renormalization group (DMRG) method for the
19-vertex model on a square lattice in order to investigate the
Berezinskii-Kosterlitz-Thouless transition. Elements of the transfer matrix of
the 19-vertex model are classified in terms of the total value of arrows in one
layer of the square lattice. By using this classification, we succeed to reduce
enormously the dimension of the matrix which has to be diagonalized in the DMRG
method. We apply our method to the 19-vertex model with the interaction
and obtain for the conformal anomaly. PACS. 05.90.+m,
02.70.-cComment: RevTeX style, 20 pages, 12 figure
Field driven recovery of the collective spin dynamics of the chiral soliton lattice
We investigate the magnetic field dependence of the spin excitation spectra of the chiral soliton lattice (CSL) in the helimagnet CrNb3S6, by
means of microwave resonance spectroscopy. The CSL is a prototype of a noncollinear spin system that forms periodically over a
macroscopic length scale. Following the field initialization of the CSL, we found three collective resonance modes over an exceptionally wide
frequency range. Upon further reducing the magnetic field toward 0 T, the spectral weight of these collective modes was disrupted by the
emergence of additional resonances whose Kittel-like field dependence was linked to coexisting field polarized magnetic domains. The collective behavior at a macroscopic level was only recovered upon reaching the helical magnetic state at 0 T. The magnetic history of this noncollinear spin system can be utilized to control microwave absorption, with potential use in magnon-driven devices
Two-State Spectral-Free Solutions of Frenkel-Moore Simplex Equation
Whilst many solutions have been found for the Quantum Yang-Baxter Equation
(QYBE), there are fewer known solutions available for its higher dimensional
generalizations: Zamolodchikov's tetrahedron equation (ZTE) and Frenkel and
Moore's simplex equation (FME). In this paper, we present families of solutions
to FME which may help us to understand more about higher dimensional
generalization of QYBE.Comment: LaTeX file. Require macros: cite.sty and subeqnarray.sty to process.
To appear in J. Phys. A: Math. and Ge
Nuclear Alpha-Particle Condensates
The -particle condensate in nuclei is a novel state described by a
product state of 's, all with their c.o.m. in the lowest 0S orbit. We
demonstrate that a typical -particle condensate is the Hoyle state
( MeV, state in C), which plays a crucial role for
the synthesis of C in the universe. The influence of antisymmentrization
in the Hoyle state on the bosonic character of the particle is
discussed in detail. It is shown to be weak. The bosonic aspects in the Hoyle
state, therefore, are predominant. It is conjectured that -particle
condensate states also exist in heavier nuclei, like O,
Ne, etc. For instance the state of O at MeV
is identified from a theoretical analysis as being a strong candidate of a
condensate. The calculated small width (34 keV) of ,
consistent with data, lends credit to the existence of heavier Hoyle-analogue
states. In non-self-conjugated nuclei such as B and C, we discuss
candidates for the product states of clusters, composed of 's,
triton's, and neutrons etc. The relationship of -particle condensation
in finite nuclei to quartetting in symmetric nuclear matter is investigated
with the help of an in-medium modified four-nucleon equation. A nonlinear order
parameter equation for quartet condensation is derived and solved for
particle condensation in infinite nuclear matter. The strong qualitative
difference with the pairing case is pointed out.Comment: 71 pages, 41 figures, review article, to be published in "Cluster in
Nuclei (Lecture Notes in Physics) - Vol.2 -", ed. by C. Beck,
(Springer-Verlag, Berlin, 2011
Exact solution of Calogero model with competing long-range interactions
An integrable extension of the Calogero model is proposed to study the
competing effect of momentum dependent long-range interaction over the original
{1 \ov r^2} interaction. The eigenvalue problem is exactly solved and the
consequences on the generalized exclusion statistics, which appears to differ
from the exchange statistics, are analyzed. Family of dual models with
different coupling constants is shown to exist with same exclusion statistics.Comment: Revtex, 6 pages, 1 figure, hermitian variant of the model included,
final version to appear in Phys. Rev.
A Symmetric Generalization of Linear B\"acklund Transformation associated with the Hirota Bilinear Difference Equation
The Hirota bilinear difference equation is generalized to discrete space of
arbitrary dimension. Solutions to the nonlinear difference equations can be
obtained via B\"acklund transformation of the corresponding linear problems.Comment: Latex, 12 pages, 1 figur
Collective ferromagnetism in two-component Fermi-degenerate gas trapped in finite potential
Spin asymmetry of the ground states is studied for the trapped
spin-degenerate (two-component) gases of the fermionic atoms with the repulsive
interaction between different components, and, for large particle number, the
asymmetric (collective ferromagnetic) states are shown to be stable because it
can be energetically favorable to increase the fermi energy of one component
rather than the increase of the interaction energy between up-down components.
We formulate the Thomas-Fermi equations and show the algebraic methods to solve
them. From the Thomas-Fermi solutions, we find three kinds of ground states in
finite system: 1) paramagnetic (spin-symmetric), 2) ferromagnetic (equilibrium)
and 3) ferromagnetic (nonequilibrium) states. We show the density profiles and
the critical atom numbers for these states obtained analytically, and, in
ferromagnetic states, the spin-asymmetries are shown to occur in the central
regions of the trapped gas, and grows up with increasing particle number. Based
on the obtained results, we discuss the experimental conditions and current
difficulties to realize the ferromagnetic states of the trapped atom gas, which
should be overcome.Comment: submit to PR
Difference Operator Approach to the Moyal Quantization and Its Application to Integrable Systems
Inspired by the fact that the Moyal quantization is related with nonlocal
operation, I define a difference analogue of vector fields and rephrase quantum
description on the phase space. Applying this prescription to the theory of the
KP-hierarchy, I show that their integrability follows to the nature of their
Wigner distribution. Furthermore the definition of the ``expectation value''
clarifies the relation between our approach and the Hamiltonian structure of
the KP-hierarchy. A trial of the explicit construction of the Moyal bracket
structure in the integrable system is also made.Comment: 19 pages, to appear in J. Phys. Soc. Jp
Vicinal Surface with Langmuir Adsorption: A Decorated Restricted Solid-on-solid Model
We study the vicinal surface of the restricted solid-on-solid model coupled
with the Langmuir adsorbates which we regard as two-dimensional lattice gas
without lateral interaction. The effect of the vapor pressure of the adsorbates
in the environmental phase is taken into consideration through the chemical
potential. We calculate the surface free energy , the adsorption coverage
, the step tension , and the step stiffness by
the transfer matrix method combined with the density-matrix algorithm. Detailed
step-density-dependence of and is obtained. We draw the roughening
transition curve in the plane of the temperature and the chemical potential of
adsorbates. We find the multi-reentrant roughening transition accompanying the
inverse roughening phenomena. We also find quasi-reentrant behavior in the step
tension.Comment: 7 pages, 12 figures (png format), RevTeX 3.1, submitted to Phys. Rev.
- …