11,218 research outputs found
Generalized Density Matrix Revisited: Microscopic Approach to Collective Dynamics in Soft Spherical Nuclei
The generalized density matrix (GDM) method is used to calculate
microscopically the parameters of the collective Hamiltonian. Higher order
anharmonicities are obtained consistently with the lowest order results, the
mean field [Hartree-Fock-Bogoliubov (HFB) equation] and the harmonic potential
[quasiparticle random phase approximation (QRPA)]. The method is applied to
soft spherical nuclei, where the anharmonicities are essential for restoring
the stability of the system, as the harmonic potential becomes small or
negative. The approach is tested in three models of increasing complexity: the
Lipkin model, model with factorizable forces, and the quadrupole plus pairing
model.Comment: submitted to Physical Review C on 08 May, 201
More on the Tensor Response of the QCD Vacuum to an External Magnetic Field
In this Letter we discuss a few issues concerning the magnetic susceptibility
of the quark condensate and the Son-Yamamoto (SY) anomaly matching equation. It
is shown that the SY relation in the IR implies a nontrivial interplay between
the kinetic and WZW terms in the chiral Lagrangian. It is also demonstrated
that in a holographic framework an external magnetic field triggers mixing
between scalar and tensor fields. Accounting for this, one may calculate the
magnetic susceptibility of the quark condensate to all orders in the magnetic
field.Comment: 20 pages, 2 figure
Self-consistent calculations of the electric giant dipole resonances in light and heavy mass nuclei
While bulk properties of stable nuclei are successfully reproduced by
mean-field theories employing effective interactions, the dependence of the
centroid energy of the electric giant dipole resonance on the nucleon number A
is not. This problem is cured by considering many-particle correlations beyond
mean-field theory, which we do within the "Quasiparticle Time Blocking
Approximation". The electric giant dipole resonances in O, Ca,
and Pb are calculated using two new Skyrme interactions.Comment: 4 pages, 4 figure
Local energy-density functional approach to many-body nuclear systems with s-wave pairing
The ground-state properties of superfluid nuclear systems with ^1S_0 pairing
are studied within a local energy-density functional (LEDF) approach. A new
form of the LEDF is proposed with a volume part which fits the Friedman-
Pandharipande and Wiringa-Fiks-Fabrocini equation of state at low and moderate
densities and allows an extrapolation to higher densities preserving causality.
For inhomogeneous systems, a surface term with two free parameters is added. In
addition to the Coulomb direct and exchange interaction energy, an effective
density-dependent Coulomb-nuclear correlation term is included with one more
free parameter, giving a contribution of the same order of magnitude as the
Nolen-Schiffer anomaly in Coulomb displacement energy. The root-mean-square
deviations from experimental masses and radii with the proposed LEDF come out
about a factor of two smaller than those obtained with the conventional
functionals based on the Skyrme or finite-range Gogny force, or on the
relativistic mean-field theory. The generalized variational principle is
formulated leading to the self-consistent Gor'kov equations which are solved
exactly, with physical boundary conditions both for the bound and scattering
states. With a zero-range density-dependent cutoff pairing interaction
incorporating a density-gradient term, the evolution of differential
observables such as odd-even mass differences and staggering in charge radii,
is reproduced reasonably well, including kinks at magic neutron numbers. An
extrapolation to infinite nuclear matter is discussed. We study also the dilute
limit in both the weak and strong coupling regime.Comment: 19 pages, 8 figures. LaTeX, with modified cls file supplied. To be
published in vol. 3 of the series "Advances in Quantum Many-Body Theory",
World Scientific (Proceedings of the MBX Conference, Seattle, September
10-15, 1999
Exclusive photoproduction of hard dijets and magnetic susceptibility of QCD vacuum
We argue that coherent production of hard dijets by linearly polarized real
photons can provide direct evidence for chirality violation in hard processes,
the first measurement of the magnetic susceptibility of the quark condensate
and the photon distribution amplitude. It can also serve as a sensitive probe
of the generalized gluon parton distribution. Numerical calculations are
presented for HERA kinematics.Comment: 4 pages, 4 figure
Search for long-lived states in antiprotonic lithium
The spectrum of the (L_i^3 + p-bar + 2e) four-body system was calculated in
an adiabatic approach. The two-electron energies were approximated by a sum of
two single-electron effective charge two-center energies as suggested in [6].
While the structure of the spectrum does not exclude the existence of
long-lived states, their experimental observability is still to be clarified
catena-Poly[[cobalt(II)-μ-aqua-μ-propanoato-κ2 O:O′-μ-propanoato-κ2 O:O] monohydrate]
The title compound, {[Co(C2H5COO)2(H2O)]·H2O}n, was synthesized by the reaction of cobalt(II) carbonate hydrate with aqueous propionic acid. The structure consists of polymeric infinite linear chains with composition [Co(C2H5COO)4/2(H2O)2/2]∞ running along [010]. The chains are formed by Co2+ ions linked with bridging propionate groups and water molecules, with a Co⋯Co distance along the chains of 3.2587 (9) Å. The Co2+ ion is six-coordinated in a strongly distorted octahedral geometry. The chains are connected to each other by a network of O—H⋯O hydrogen bonds involving solvent water molecules
Modeling the jet quenching, thermal resonance production and hydrodynamical flow in relativistic heavy ion collisions
The event topology in relativistic heavy ion collisions is determined by
various multi-particle production mechanisms. The simultaneous model treatment
of different collective nuclear effects at high energies (such as a hard
multi-parton fragmentation in hot QCD-matter, thermal resonance production,
hydrodynamical flows, etc.) is actual but rather complicated task. We discuss
the simulation of the above effects by means of Monte-Carlo model HYDJET++.Comment: Talk given at Workshop "Hot Quarks 2010" (La Londe Les Maures,
France, June 21-26, 2010); 4 pages including 2 figures as EPS-files; prepared
using LaTeX package for publication in Journal of Physics: Conference Serie
Strong coupling constants of bottom and charmed mesons with scalar, pseudoscalar and axial vector kaons
The strong coupling constants, , ,
, , and
, where , and are scalar, pseudoscalar
and axial vector kaon mesons, respectively are calculated in the framework of
three-point QCD sum rules. In particular, the correlation functions of the
considered vertices when both and mesons are off-shell
are evaluated. In the case of , which is either or
, the mixing between these two states are also taken into account. A
comparison of the obtained result with the existing prediction on
as the only coupling constant among the considered
vertices, previously calculated in the literature, is also made.Comment: 20 Pages, 3 Figures and 8 Table
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