7,333 research outputs found
Interfering Doorway States and Giant Resonances. II: Transition Strengths
The mixing of the doorway components of a giant resonance (GR) due to the
interaction via common decay channels influences significantly the distribution
of the multipole strength and the energy spectrum of the decay products of the
GR. The concept of the partial widths of a GR becomes ambiguous when the mixing
is strong. In this case, the partial widths determined in terms of the - and
-matrices must be distinguished. The photoemission turns out to be most
sensitive to the overlapping of the doorway states. At high excitation
energies, the interference between the doorway states leads to a restructuring
towards lower energies and apparent quenching of the dipole strength.Comment: 17 pages, LaTeX, 5 figures as JPEG, to appear in PRC (July 1997
Polarization of the fermionic vacuum by a global monopole with finite core
We study the vacuum polarization effects associated with a massive fermionic
field in a spacetime produced by a global monopole considering a nontrivial
inner structure for it. In the general case of the spherically symmetric static
core with finite support we evaluate the vacuum expectation values of the
energy-momentum tensor and the fermionic condensate in the region outside the
core. These quantities are presented as the sum of point-like global monopole
and core-induced contributions. The asymptotic behavior of the core-induced
vacuum densities are investigated at large distances from the core, near the
core and for small values of the solid angle corresponding to strong
gravitational fields. As an application of general results the flower-pot model
for the monopole's core is considered and the expectation values inside the
core are evaluated.Comment: 22 pages, 4 figure
Phase Transitions in liquid Helium 3
The phase transitions of liquid Helium 3 are described by truncations of an
exact nonperturbative renormalization group equation. The location of the first
order transition lines and the jump in the order parameter are computed
quantitatively. At the triple point we find indications for partially universal
behaviour. We suggest experiments that could help to determine the effective
interactions between fermion pairs.Comment: 4 pages, 6 figures, LaTe
Compact objects in conformal nonlinear electrodynamics
In this paper we consider a special case of vacuum non-linear electrodynamics
with a stress-energy tensor conformal to the Maxwell theory. Distinctive
features of this model are: the absence of dimensional parameter for
non-linearity description and a very simple form of the dominant energy
condition, which can be easily verified in an arbitrary pseudo-riemannian
space-time with the consequent constrains on the model parameters. In this
paper we analyse some properties of astrophysical compact objects coupled to
conformal vacuum non-linear electrodynamics
- …