6,685 research outputs found
Rotational alignment near N=Z and proton-neutron correlations
The effects of the residual proton-neutron interactions on bandcrossing
features are studied by means of shell model calculations for nucleons in a
high-j intruder orbital. The presence of an odd-nucleon shifts the frequency of
the alignment of two nucleons of the other kind along the axis of rotation. It
is shown that the anomalous delayed crossing observed in nuclei with aligning
neutrons and protons occupying the same intruder subshell can be partly
attributed to these residual interactions.Comment: 14 pages, including 5 eps figures submitted to Phys. Rev.
Symmetry Breaking by Proton-Neutron Pairing
The symmetries of the and pair-fields are different. The
consequences for rotational spectra are discussed. For , the concept of
spontaneous breaking and subsequent restoration of the isospin symmetry turns
out to be important. It permits us to describe the proton-neutron
pair-correlation within the conventional frame of pairing between like
particles. The experimental data are consistent with the presence of a
field at low spin in nuclei. For a substantial field, the
spectra of even-even and odd-odd nuclei become similar. The
possibility of a rotationally induced pair-field at high spin is
considered.Comment: 7 pages 9 figure
Can the string scale be related to the cosmic baryon asymmetry?
In a previous work, a mechanism was presented by which baryon asymmetry can
be generated during inflation from elliptically polarized gravitons.
Nonetheless, the mechanism only generated a realistic baryon asymmetry under
special circumstances which requires an enhancement of the lepton number from
an unspecified GUT. In this note we provide a stringy embedding of this
mechanism through the Green-Schwarz mechanism, demonstrating that if the
model-independent axion is the source of the gravitational waves responsible
for the lepton asymmetry, one can observationally constrain the string scale
and coupling.Comment: 12 Pages, typo corrected in the tex
Isovector and isoscalar superfluid phases in rotating nuclei
The subtle interplay between the two nuclear superfluids, isovector T=1 and
isoscalar T=0 phases, are investigated in an exactly soluble model. It is shown
that T=1 and T=0 pair-modes decouple in the exact calculations with the T=1
pair-energy being independent of the T=0 pair-strength and vice-versa. In the
rotating-field, the isoscalar correlations remain constant in contrast to the
well known quenching of isovector pairing. An increase of the isoscalar (J=1,
T=0) pair-field results in a delay of the bandcrossing frequency. This
behaviour is shown to be present only near the N=Z line and its experimental
confirmation would imply a strong signature for isoscalar pairing collectivity.
The solutions of the exact model are also discussed in the
Hartree-Fock-Bogoliubov approximation.Comment: 5 pages, 4 figures, submitted to PR
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