12,430 research outputs found
Bogoliubov quasiparticle spectra of the effective d-wave model for cuprate superconductivity
An exact-diagonalization technique on finite-size clusters is used to study
the ground state and excitation spectra of the two-dimensional effective
fermion model, a fictious model of hole quasiparticles derived from numerical
studies of the two-dimensional t-J model at low doping. We show that there is
actually a reasonable range of parameter values where the -wave
pairing of holes occurs and the low-lying excitation can be described by the
picture of Bogoliubov quasiparticles in the BCS pairing theory. The gap
parameter of a size (where is the attractive
interaction between holes) is estimated at low doping levels. The paired state
gives way to the state of clustering of holes for some stronger attractions.Comment: 4 pages, RevTeX. Figures available upon request to
[email protected]. To be published in Phys. Rev.
Pre-scission neutron multiplicity associated with the dynamical process in superheavy mass region
The fusion-fission process accompanied by neutron emission is studied in the
superheavy-mass region on the basis of the fluctuation-dissipation model
combined with a statistical model. The calculation of the trajectory or the
shape evolution in the deformation space of the nucleus with neutron emission
is performed. Each process (quasi-fission, fusion-fission, and deep
quasi-fission processes) has a characteristic travelling time from the point of
contact of colliding nuclei to the scission point. These dynamical aspects of
the whole process are discussed in terms of the pre-scission neutron
multiplicity, which depends on the time spent on each process. We have
presented the details of the characteristics of our model calculation in the
reactions Ca+Pb and Ca+Pu, and shown how the
structure of the distribution of pre-scission neutron multiplicity depends on
the incident energy.Comment: 19 pages, 12 figures, Accepted for publication in J. Phys.
Picard-Fuchs Equations and Whitham Hierarchy in N=2 Supersymmetric SU(r+1) Yang-Mills Theory
In general, Whitham dynamics involves infinitely many parameters called
Whitham times, but in the context of N=2 supersymmetric Yang-Mills theory it
can be regarded as a finite system by restricting the number of Whitham times
appropriately. For example, in the case of SU(r+1) gauge theory without
hypermultiplets, there are r Whitham times and they play an essential role in
the theory. In this situation, the generating meromorphic 1-form of the Whitham
hierarchy on Seiberg-Witten curve is represented by a finite linear combination
of meromorphic 1-forms associated with these Whitham times, but it turns out
that there are various differential relations among these differentials. Since
these relations can be written only in terms of the Seiberg-Witten 1-form,
their consistency conditions are found to give the Picard-Fuchs equations for
the Seiberg-Witten periods.Comment: to be published in J. Math. Phys, revtex, 14 page
Dual WDVV Equations in N=2 Supersymmetric Yang-Mills Theory
This paper studies the dual form of Witten-Dijkgraaf-Verlinde-Verlinde (WDVV)
equations in N=2 supersymmetric Yang-Mills theory by applying a duality
transformation to WDVV equations. The dual WDVV equations called in this paper
are non-linear differential equations satisfied by dual prepotential and are
found to have the same form with the original WDVV equations. However, in
contrast with the case of weak coupling calculus, the perturbative part of dual
prepotential itself does not satisfy the dual WDVV equations. Nevertheless, it
is possible to show that the non-perturbative part of dual prepotential can be
determined from dual WDVV equations, provided the perturbative part is given.
As an example, the SU(4) case is presented. The non-perturbative dual
prepotential derived in this way is consistent to the dual prepotential
obtained by D'Hoker and Phong.Comment: misprints are corrected, revtex, 10 page
Possibility of synthesizing doubly closed superheavy nucleus
The possibility of synthesizing a doubly magic superheavy nucleus,
, is investigated on the basis of fluctuation-dissipation
dynamics. In order to synthesize this nucleus, we must generate more
neutron-rich compound nuclei because of the neutron emissions from excited
compound nuclei. The compound nucleus has two advantages to
achieving a high survival probability. First, because of small neutron
separation energy and rapid cooling, the shell correction energy recovers
quickly. Secondly, owing to neutron emissions, the neutron number of the
nucleus approaches that of the double closed shell and the nucleus obtains a
large fission barrier. Because of these two effects, the survival probability
of does not decrease until the excitation energy MeV.
These properties lead to a rather high evaporation reside cross section.Comment: 5 pages, 6 figure
Exact Solution for Relativistic Two-Body Motion in Dilaton Gravity
We present an exact solution to the problem of the relativistic motion of 2
point masses in dimensional dilaton gravity. The motion of the bodies
is governed entirely by their mutual gravitational influence, and the spacetime
metric is likewise fully determined by their stress-energy. A Newtonian limit
exists, and there is a static gravitational potential. Our solution gives the
exact Hamiltonian to infinite order in the gravitational coupling constant.Comment: 6 pages, latex, 3 figure
Skyrmions coupled with the electromagnetic field via the gauged Wess-Zumino term
In soliton models expressed in terms of the non-linear chiral field, the
electric current has an anomalous gauge-field contribution as the baryon
current does. We study the spin polarized Skyrmions coupled with the
electromagnetic field via the gauged Wess-Zumino term and calculate
configurations of the Skyrmion and the gauge field with boundary conditions to
ensure the physical charge number for baryons.
Although the electromagnetic field via the gauged Wess-Zumino term affects
physical quantities in small amounts, we find that the magnetic field forms a
dipole structure owing to a circular electric current around the spin
quantization axis of the soliton. This is understood on an analogy with the
Meissner effect in the super conductor.The electric charge distributions turn
out to have characteristic structures depending on the total charge, which
suggests the intrinsic deformation of baryons due to orbital motions of the
constituents.Comment: 8 pages, 5 figure
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