14,339 research outputs found
Scalar field phase dynamics in preheating
We study the model of a massive inflaton field coupled to another
scalar filed with interaction term for the first stage
of preheating. We obtain the the behavior of the phase in terms of the
iteration of a simple family of circle maps. When expansion of the universe is
taken into account the qualitative behavior of the phase and growth number
evolution is reminiscent of the behavior found in the case without expansion.Comment: 4 pages, 4 figures, LaTeX; submitted to the Proceedings of Eleventh
Marcel Grossmann Meetin
Large N WZW Field Theory Of N=2 Strings
We explore the quantum properties of self-dual gravity formulated as a large
two-dimensional WZW sigma model. Using a non-trivial classical background,
we show that a space-time is generated. The theory contains an infinite
series of higher point vertices. At tree level we show that, in spite of the
presence of higher than cubic vertices, the on-shell 4 and higher point
functions vanish, indicating that this model is related with the field theory
of closed N=2 strings. We examine the one-loop on-shell 3-point amplitude and
show that it is ultra-violet finite.Comment: This is the final version. By editorial mistake at Phys.Lett.B an
older version was published in prin
Two neutron decay of 16Be
Recently, the first example of two-neutron decay from the ground state of an
unbound nucleus, Be, was seen. Three-body methods are ideal for exactly
treating the degrees of freedom important for these decays. Using a basis
expansion over hyperspherical harmonics and the hyperspherical R-matrix method,
we construct a realistic model of Be in order to investigate its decay
mode and the role of the two-neutron interaction. The neutron-Be
interaction is constrained using shell model predictions. We obtain a ground
state for Be that is over-bound by approximately 1 MeV with a width of
approximately 0.23 MeV. This suggests, that for such systems, the three-body
force needs to be repulsive.Comment: 4 pages, 1 figure, contribution to the proceedings for the 21st
International Conference on Few Body Problems in Physics, Chicago, Illinois,
US
Status of reaction theory for studying rare isotopes
Reactions are an important tool to study nuclear structure and for extracting
reactions relevant for astrophysics. In this paper we focus on deuteron induced
reactions which can provide information on neutron shell evolution as well as
neutron capture cross sections. We review recent work on the systematic
comparison of the continuum discretized coupled channel method, the adiabatic
wave approximation and the Faddeev momentum-space approach. We also explore
other aspects of the reaction mechanism and discuss in detail difficulties
encountered in the calculations.Comment: 7 pages, 5 figures, proceeding for HITES 201
On quasi-Jacobi and Jacobi-quasi bialgebroids
We study quasi-Jacobi and Jacobi-quasi bialgebroids and their relationships
with twisted Jacobi and quasi Jacobi manifolds. We show that we can construct
quasi-Lie bialgebroids from quasi-Jacobi bialgebroids, and conversely, and also
that the structures induced on their base manifolds are related via a quasi
Poissonization
- …