From pub_off@ictp.trieste.it Sun Mar 11 15:15:04 2001
Date: Tue, 6 Mar 2001 10:56:40 +0100
From: Publications Office
To: preprints@ictp.trieste.it
Subject: 12th List of 2000 ICTP Preprints
+---------------------- "ICTP SCIENTIFIC PREPRINTS LIST" ------------------+ | Automatic e-mail delivery service of recent ICTP Preprints Titles | | SOURCES can be retrieved from URL: http://www.ictp.trieste.it/~pub_off | HARD COPIES are available by e-mail request to: pub_off@ictp.trieste.it | by quoting the ICTP preprint number and giving your full postal address +--------------------------------------------------------------------------+
2000LIST-12
This is the twelfth list of 2000 ICTP preprints which are available.
+--------------------------------------------------------------+
ICTP Preprint No.IC2000099
FRACTIONAL SUPERSYMMETRY THROUGH GENERALIZED ANYONIC ALGEBRA
by Jamila Douari and Yassine Hassouni
ABSTRACT: The construction of anyonic operators and algebra is
generalized by using quons operators. Therefore, the particular version
of fractional supersymmetry is constructed on the two-dimensional
lattice by associating two generalized anyons of different kinds. The
fractional supersymmetry Hamiltonian operator is obtained on the
two-dimensional lattice and the quantum algebra $U_{q}(sl_{2})$ is
realized.
ICTP Preprint No.IC2000100
THE FSUSY HAMILTONIAN IN CONNECTION WITH THE CHERN-SIMONS GAUGE THEORY
by J. Douari and Y. Hassouni
ABSTRACT: On the two-dimensional lattice, the construction of anyonic
operators and its algebras is discussed. Thus, the fractional supersymetry
(FSUSY) and the associated FSUSY Hamiltonian basing on the quonic anyons
are recalled. Its particular case for bosonic anyon and fermionic anyon is
given. The FSUSY Hamiltonian in connection with the Chern-Simons gauge
theory is constructed.
ICTP Preprint No.IC2000101
GENERALIZED FRACTIONAL SUPERSYMMETRY ASSOCIATED TO DIFFERENT
SPECIES OF ANYONS
by Jamila Douari and Yassine Hassouni
ABSTRACT: We consider multiple species of anyons characterized by
different statistical parameters. First, we redefine the anyonic algebra
and then generalize this definition by constructing the anyonic
superalgebra. Finally, we use these tools to generalize the fractional
supersymmetry already discussed in Douari and Hassouni (2000).
ICTP Preprint No.IC2000110
NON-LOCAL ENERGY DENSITY FUNCTIONALS:
MODELS PLUS SOME EXACT GENERAL RESULTS
by N.H. March
ABSTRACT: Holas and March (Phys. Rev. {\bf A51}, 2040, 1995) gave a
formally exact expression for the force $-\frac{\partial V_{xc}(\r
)}{\partial\r}$ associated with the exchange-correlation
potential $V_{xc}(\r )$ of density functional theory. This forged a precise
link between first- and second-order density matrices and $V_{xc}(\r )$.
Here models are presented in which these low-order matrices can be related
to the ground-state electron density. This allows non-local energy density
functionals to be constructed within the framework of such models. Finally,
results emerging from these models have led to the derivation of some
exact 'nuclear cusp' relations for exchange and correlation energy
densities in molecules, clusters and condensed phases.
ICTP Preprint No.IC2000146
SOLVING THE GENERAL TRUNCATED MOMENT PROBLEM
BY $r$-GENERALIZED FIBONACCI SEQUENCES METHOD
by C.E. Chidume, M. Rachid and E.H. Zerouali
ABSTRACT: We give in this paper a new method for solving the generalized
truncated power moment problem. To this aim we use $r$-generalized
Fibonacci sequences and their associated minimal polynomials. We provide an
algorithm of construction of solutions in a short method. This method
allows us to avoid any appeal to Hankel matrices or any positive
difiniteness conditions as in Flessas-Burton-Whitehead (FBW) approach.
Examples and general cases are discussed.
ICTP Preprint No.IC2000147
PHOTOPRODUCTION OF AXIONS IN A RESONANT ELECTROMAGNETIC CAVITY
by Dang Van Soa, Hoang Ngoc Long, Ha Huy Bang and Nguyen Mai Hung
ABSTRACT: Photon - axion conversions in a resonant electromagnetic
cavity with frequency equal to the axion mass are considered
in detail by the Feynman diagram methods. The differential cross
sections are presented and numerical evaluations are given. It is shown
that there is a resonant conversion for the considered process. From our
results, some estimates for experimental conditions are given.
ICTP Preprint No.IC2000148
EMISSION OF INTERMEDIATE MASS FRAGMENTS IN THE HEAVY ION INTERACTION
OF (14.0 MeV/u) Pb + Au
by E.U. Khan, I.E. Qureshi, M.I. Shahzad, F.N. Khattak and H.A. Khan
ABSTRACT: We have studied the heavy ion interactions of (14.0 MeV/u) Pb +
Au using two threshold detectors, mica and CN-85. A thin layer of Au was
deposited on each of the three mica and two CN-85 detector pieces. These
target-detector assemblies were exposed to a beam of 14.0 MeV/u Pb ions
having the fluence of $1.5\otimes 106 /cm^2$ at GSI, Darmstadt, Germany.
After removing the target material and etching the samples in appropriate
etchants, we scanned 32.29 cm$^2$ and 24.97 cm$^2$ area of mica and CN-85,
respectively. Based on the observed number of events of various
multiplicities, we have determined the total as well as partial
experimental reaction cross sections. It is shown that a significant number
of intermediate mass fragments are emitted alongwith the heavy fragments in
the present reaction.
ICTP Preprint No.IC2000149
ANOMALOUS $U(1)_{A}$ AND ELECTROWEAK SYMMETRY BREAKING
by Ilia Gogoladze and Mirian Tsulaia
ABSTRACT: We suggest a mechanism for electroweak symmetry breaking
in the Supersymmetric Standard Model. Our suggestion is based on the
presence of an anomalous $U(1)_{A}$ gauge symmetry,
which naturally arises in the four dimensional superstring theory, and
heavily relies on the value of the corresponding Fayet-Illiopoulos $\xi$-
term.
ICTP Preprint No.IC2000150
DIFFERENTIAL THERMOPOWER OF A CHIRAL CARBON NANOTUBE
by S.Y. Mensah, F.K.A. Allotey, N.G. Mensah and G. Nkrumah
ABSTRACT: Differential thermopower of a chiral carbon nanotube (CNT) was
calculated using a tractable analytical approach. We obtained an expression
for the electrical conductivity $\sigma $ and the thermopower $\alpha $.
The results were numerically analysed. We noted from the values of $\alpha$
that the material can behave as a semimetal, n-type semiconductor and p-
type as well, depending on the parameters of the CNT. We proposed the use
of CNT as thermoelement.
ICTP Preprint No.IC2000151
GROUND STATE ENERGY OF A POLARON IN A SUPERLATTICE
by S.Y. Mensah, F.K.A. Allotey, G. Nkrumah and N.G. Mensah
ABSTRACT: The ground state energy of a polaron in a superlattice was
calculated using the double-time Green functions. The effective mass of the
polaron along the planes perpendicular to the superlattice axis was also
calculated. The dependence of the ground state energy and the effective
mass along the planes perpendicular to the superlattice axis on the
electron-phonon coupling constant $\alpha $ and on the superlattice
parameters (i.e. the superlattice period $d$ and the bandwidth $\Delta $)
were studied. It was observed that if an infinite square well potential is
assumed, the ground state energy of the polaron decreases (i.e. becomes
more negative) with increasing $\alpha $ and $d$, but increases with
increasing $\Delta $. For small values of $\alpha $, the polaron ground
state energy varies slowly with $\Delta $, becoming approximately constant
for large $\Delta $. The effective mass along the planes perpendicular to
the superlattice axis was found to be approximately equal to the mass of an
electron for all typical values of $\alpha $, $d$ and $\Delta $.
ICTP Preprint No.IC2000153
ON THE SOLVABILITY IN A CLOSED FORM OF A CLASS OF
SINGULAR INTEGRAL EQUATIONS
by Nguyen Van Mau and Nguyen Minh Tuan
ABSTRACT: This paper deals with the solvability of singular integral
equations of the form $$\sum_{k=1}^na_k(t)\varphi(\epsilon_kt)
+\sum_{k=1}^n\frac{1}{ \pi i}
\int\limits_{\Gamma}\frac{\tau^{n-1-k}t^k}{
\tau^n-t^n}m_k(\tau,t)\varphi(\tau)d\tau = f(t),\eqno(1)$$
where $\Gamma$ is the unit circle on the complex plane, $\epsilon_1=\exp
(2\pi i/n), \epsilon_k=\epsilon_1^k.$ We indicate that equation (1) is
exactly a singular integral equation of Cauchy type with certain shift. The
method in this paper is to reduce equation (1) to the well-known Riemann
boundary value problems and describe solutions in a closed form.
ICTP Preprint No.IC2000154
DISCRETE PLANCK SPECTRA
by Valentin I. Vlad and Nicholas Ionescu-Pallas
ABSTRACT: The Planck radiation spectrum of ideal cubic and spherical
cavities, in the region of small adiabatic invariance $\gamma =TV^{1/3}$,
is shown to be discrete and strongly dependent on the cavity geometry and
temperature. This behavior is the consequence of the random distribution of
the state weights in the cubic cavity and of the random overlapping of the
successive multiplet components, for the spherical cavity. The total energy
(obtained by summing up the exact contributions of the eigenvalues and
their weights, for low values of the adiabatic invariance) does not obey
any longer Stefan-Boltzmann law. The new law includes a corrective factor
depending on $\gamma$ and imposes a faster decrease of the total energy to
zero, for $\gamma\to 0$. We have defined the double quantized regime both
for cubic and spherical cavities by the superior and inferior limits put on
the principal quantum numbers or the adiabatic invariance. The total energy
of the double quantized cavities shows large differences from the classical
calculations over unexpected large intervals, which are measurable and put
in evidence important macroscopic quantum effects.
ICTP Preprint No.IC2000155
GENERAL THEORY TO DETERMINE THE CRITICAL CHARGE DENSITY
by Floran Vila
ABSTRACT: In this work we determine theoretically the critical
charge density in the system grounded metallic sphere, uniformly charged
dielectric plane, in the presence of grounded surfaces, in a more
general case. Special attention is payed to the influence of the
system geometry in determining the most optimal conditions for
obtaining the minimum critical charge density. This is a situation
frequently encountered in industrial condition and is important in
evaluating the danger of the electrostatic discharges.
ICTP Preprint No.IC2000156
ALGEBRAIC CHARACTERIZATIONS OF GENERALIZED RIGHT INVERTIBLE
OPERATORS OF DEGREE $k$
by Nguyen Van Mau, Pham Thi Bach Ngoc and Nguyen Minh Tuan
ABSTRACT: Ng. V. Mau and Ng. M. Tuan (1997) constructed a class of
generalized right invertible operators of degree $k$ and investigaated the
algebraic characterizations of these operators. In this paper, we obtain
the algebraaic characterizations of the generalized right invertible
operators of degree $k, k>1.$
ICTP Preprint No.IC2000190
STOCHASTICS THEORY OF LOG-PERIODIC PATTERNS
by Enrique Canessa
ABSTRACT: We introduce an analytical model based on birth-death clustering
processes to help understand the empirical log-periodic corrections to
power-law scaling and the finite-time singularity as reported in several
domains including rupture, earthquakes, world population and financial
systems. In our stochastics theory log-periodicities are a consequence of
transient clusters induced by an entropy-like term that may reflect the
amount of cooperative information carried by the state of a large system of
different species. The clustering completion rates for the system are
assumed to be given by a simple linear death process. The singularity
at $t_{o}$ is derived in terms of birth-death clustering coefficients.
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