3 research outputs found
Double-Dipole Excitations in 40Ca
The double-dipole strength distribution in Ca is calculated
microscopically within a model space of 1p1h - and 2p2h excitations. Anharmonic
effects in the centroid energies of the - and components are found
to be small, in agreement with experimental observation. Firm conclusions about
the spreading width cannot be drawn, as yet, due to computational limitations
in the number of 2p2h states.Comment: 8 pages of LaTeX, two figures available at
ftp://rsm1.physcis.uiuc.edu/pub/figs
A Non-Perturbative Treatment of the Pion in the Linear Sigma-Model
Using a non-perturbative method based on the selfconsistent Quasi-particle
Random-Phase Approximation (QRPA) we describe the properties of the pion in the
linear -model. It is found that the pion is massless in the chiral
limit, both at zero- and finite temperature, in accordance with Goldstone's
theorem.Comment: To appear in Nucl.Phys. A, 16 pages, 2 Postscript figure