1,871 research outputs found
On the Accuracy of Hyperspherical Harmonics Approaches to Photonuclear Reactions
Using the Lorentz Integral Transform (LIT) method we compare the results for
the triton total photodisintegration cross section obtained using the
Correlated Hyperspherical Harmonics (CHH) and the Effective Interaction
Hyperspherical Harmonics (EIHH) techniques. We show that these two approaches,
while rather different both conceptually and computationally, lead to results
which coincide within high accuracy. The calculations which include two- and
three-body forces are of the same high quality in both cases. We also discuss
the comparison of the two approaches in terms of computational efficiency.
These results are of major importance in view of applications to the much
debated case of the four-nucleon photoabsorption.Comment: 12 pages, 3 figure
On the control of a linear functional- differential equation with quadratic cost
Linear functional differential equations control with quadratic cos
The effective interaction hyperspherical harmonics method for non-local potentials
A different formulation of the effective interaction hyperspherical harmonics
(EIHH) method, suitable for non-local potentials, is presented. The EIHH method
for local interactions is first shortly reviewed to point out the problems of
an extension to non-local potentials. A viable solution is proposed and, as an
application, results on the ground-state properties of 4- and 6-nucleon systems
are presented. One finds a substantial acceleration in the convergence rate of
the hyperspherical harmonics series. Perspectives for an application to
scattering cross sections, via the Lorentz transform method are discussed.Comment: 6 pages, 1 figure, to be published in the Proceedings of the
International Nuclear Physics Conference, Vancouver, 201
Incorporation of three-nucleon force in the effective interaction hyperspherical harmonic approach
It is shown how a bare three-nucleon force is incorporated into the formalism
of the effective interaction approach for hyperspherical harmonics. As a
practical example we calculate the ground state properties of 3H and 3He using
the Argonne V18 nucleon-nucleon potential and the Urbana IX three-nucleon
force. A very good convergence of binding energies and matter radii is
obtained. We also find a very good agreement of our results compared to other
high precision calculations.Comment: 17 pages, 3 figure
Few body Calculation of Neutrino Neutral Inelastic scattering on 4He
The inelastic neutral reaction of neutrino on 4He is calculated using two
modern nucleon--nucleon potentials. Full final state interaction among the four
nucleons is considered, via the Lorentz integral transform (LIT) method. The
effective interaction hyperspherical-harmonic (EIHH) approach is used to solve
the resulting Schrodinger like equations. A detailed energy dependent
calculation is given in the impulse approximation.Comment: 4 pages; talk at 18th International Conference on Few-Body Problems
in Physics (FB18), Santos, SP, Brazil, August 200
On the structure of just infinite profinite groups
A profinite group is just infinite if every closed normal subgroup of
is of finite index. We prove that an infinite profinite group is just infinite
if and only if, for every open subgroup of , there are only finitely
many open normal subgroups of not contained in . This extends a result
recently established by Barnea, Gavioli, Jaikin-Zapirain, Monti and Scoppola,
who proved the same characterisation in the case of pro- groups. We also use
this result to establish a number of features of the general structure of
profinite groups with regard to the just infinite property.Comment: 16 page
Neutrino Breakup of A=3 Nuclei in Supernovae
We extend the virial equation of state to include 3H and 3He nuclei, and
predict significant mass-three fractions near the neutrinosphere in supernovae.
While alpha particles are often more abundant, we demonstrate that energy
transfer cross-sections for muon and tau neutrinos at low densities are
dominated by breakup of the loosely-bound 3H and 3He nuclei. The virial
coefficients involving A=3 nuclei are calculated directly from the
corresponding nucleon-3H and nucleon-3He scattering phase shifts. For the
neutral-current inelastic cross-sections and the energy transfer cross
sections, we perform ab-initio calculations based on microscopic two- and
three-nucleon interactions and meson-exchange currents.Comment: 6 pages, 2 figures, minor additions, to appear in Phys. Rev.
Are there compact heavy four-quark bound states?
We present an exact method to study four-quark systems based on the
hyperspherical harmonics formalism. We apply it to several physical systems of
interest containing two heavy and two light quarks using different quark-quark
potentials. Our conclusions mark the boundaries for the possible existence of
compact, non-molecular, four-quark bound states. While states
may be stable in nature, the stability of states would imply
the existence of quark correlations not taken into account by simple quark
dynamical modelsComment: 10 pages, 1 figure. Accepted for publication in Phys. Rev.
- …