14,965 research outputs found
Deduction of the quantum numbers of low-lying states of 6-nucleon systems based on symmetry
The inherent nodal structures of the wavefunctions of 6-nucleon systems have
been investigated. The existence of a group of six low-lying states dominated
by L=0 has been deduced. The spatial symmetries of these six states are found
to be mainly {4,2} and {2,2,2}.Comment: 8 pages, no figure
Breathing oscillations of a trapped impurity in a Bose gas
Motivated by a recent experiment [J. Catani et al., arXiv:1106.0828v1
preprint, 2011], we study breathing oscillations in the width of a harmonically
trapped impurity interacting with a separately trapped Bose gas. We provide an
intuitive physical picture of such dynamics at zero temperature, using a
time-dependent variational approach. In the Gross-Pitaevskii regime we obtain
breathing oscillations whose amplitudes are suppressed by self trapping, due to
interactions with the Bose gas. Introducing phonons in the Bose gas leads to
the damping of breathing oscillations and non-Markovian dynamics of the width
of the impurity, the degree of which can be engineered through controllable
parameters. Our results reproduce the main features of the impurity dynamics
observed by Catani et al. despite experimental thermal effects, and are
supported by simulations of the system in the Gross-Pitaevskii regime.
Moreover, we predict novel effects at lower temperatures due to self-trapping
and the inhomogeneity of the trapped Bose gas.Comment: 7 pages, 3 figure
Imprints of the nuclear symmetry energy on gravitational waves from the axial w-modes of neutron stars
The eigen-frequencies of the axial w-modes of oscillating neutron stars are
studied using the continued fraction method with an Equation of State (EOS)
partially constrained by the recent terrestrial nuclear laboratory data. It is
shown that the density dependence of the nuclear symmetry energy
affects significantly both the frequencies and the damping
times of these modes. Besides confirming the previously found universal
behavior of the mass-scaled eigen-frequencies as functions of the compactness
of neutron stars, we explored several alternative universal scaling functions.
Moreover, the -mode is found to exist only for neutron stars having a
compactness of independent of the EOS used.Comment: Version appeared in Phys. Rev. C80, 025801 (2009
Towards a microscopic construction of flavour vacua from a space-time foam model
The effect on flavour oscillations of simple expanding background
space-times, motivated by some D-particle foam models, is calculated for a
toy-model of bosons with flavour degrees of freedom. The presence of D-particle
defects in the space-time, which can interact non trivially (via particle
capture) with flavoured particles in a flavour non-preserving way, generates
mixing in the effective field theory of low-energy string excitations.
Moreover, the recoil of the D-particle defect during the capture/scattering
process implies Lorentz violation, which however may be averaged to zero in
isotropic D-particle populations, but implies non-trivial effects in
correlators. Both features imply that the flavoured mixed state sees a
non-trivial flavour (Fock-space) vacuum of a type introduced earlier by Blasone
and Vitiello in a generic context of theories with mixing. We discuss the
orthogonality of the flavour vacua to the usual Fock vacua and the effect on
flavour oscillations in these backgrounds. Furthermore we analyse the equation
of state of the Flavour vacuum, and find that, for slow expansion rates induced
by D particle recoil, it is equivalent to that of a cosmological constant. Some
estimates of these novel non-perturbative contribution to the vacuum energy are
made. The contribution vanishes if the mass difference and the mixing angle of
the flavoured states vanish.Comment: 27 pages RevTex, 2 eps figures incorporate
New magnetic phase in metallic V_{2-y}O_3 close to the metal insulator transition
We have observed two spin density wave (SDW) phases in hole doped metallic
V_{2-y}O_3, one evolves from the other as a function of doping, pressure or
temperature. They differ in their response to an external magnetic field, which
can also induce a transition between them. The phase boundary between these two
states in the temperature-, doping-, and pressure-dependent phase diagram has
been determined by magnetization and magnetotransport measurements. One phase
exists at high doping level and has already been described in the literature.
The second phase is found in a small parameter range close to the boundary to
the antiferromagnetic insulating phase (AFI). The quantum phase transitions
between these states as a function of pressure and doping and the respective
metamagnetic behavior observed in these phases are discussed in the light of
structurally induced changes of the band structure.Comment: REVTeX, 8 pages, 12 EPS figures, submitted to PR
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