153 research outputs found
Strange-quark contribution to the ratio of neutral- to charged-current cross sections in neutrino-nucleus scattering
A formalism based on a relativistic plane wave impulse approximation is
developed to investigate the strange-quark content () of the
axial-vector form factor of the nucleon via neutrino-nucleus scattering.
Nuclear structure effects are incorporated via an accurately calibrated
relativistic mean-field model. The ratio of neutral- to charged-current cross
sections is used to examine the sensitivity of this observable to .
For values of the incident neutrino energy in the range proposed by the FINeSSE
collaboration and by adopting a value of , a 30% enhancement
in the ratio is observed relative to the result.Comment: 20 pages, 6 figures, Revtex, Submitted to Phys. Rev.
Neutrino-Nucleus Reactions and Muon Capture in 12C
The neutrino-nucleus cross section and the muon capture rate are discussed
within a simple formalism which facilitates the nuclear structure calculations.
The corresponding formulae only depend on four types of nuclear matrix
elements, which are currently used in the nuclear beta decay. We have also
considered the non-locality effects arising from the velocity-dependent terms
in the hadronic current. We show that for both observables in 12C the higher
order relativistic corrections are of the order of ~5 only, and therefore do
not play a significant role. As nuclear model framework we use the projected
QRPA (PQRPA) and show that the number projection plays a crucial role in
removing the degeneracy between the proton-neutron two quasiparticle states at
the level of the mean field. Comparison is done with both the experimental data
and the previous shell model calculations. Possible consequences of the present
study on the determination of the neutrino oscillation
probability are briefly addressed.Comment: 29 pages, 6 figures, Revtex4. Several changes were made to the
previous manuscript, the results and final conclusions remain unalterable. It
has been accepted for publication as a Regular Article in Physical Review
Neutrino-nucleus interactions at low energies within Fermi-liquid theory
Cross sections are calculated for neutrino scattering off heavy nuclei at
energies below 50 MeV. The theory of Fermi liquid is applied to estimate the
rate of neutrino-nucleon elastic and inelastic scattering in a nuclear medium
in terms of dynamic form factors. The cross sections, obtained here in a rather
simple way, are in agreement with the results of the other much more
sophisticated nuclear models. A background rate from the solar neutrino
interactions within a large Ge detector is estimated in the above-mentioned
approach. The knowledge of the rate is in particular rather important for
new-generation large-scale neutrino experiments.Comment: 9 pages, 6 figure
Theory of doorway states for one-nucleon transfer reactions. II. Model-independent study of nuclear correlation effects
The correlation effects in nuclei owing to which the nuclear wave functions
are different from the Slater determinants are studied on the basis of the
original theory. The calculated numbers of nucleons out of the nuclear
Fermi-surface are in reasonable agreement with the finding from the
high-momentum components of the nucleon momentum distributions in nuclei. The
problems concerning the nuclear binding energy are also discussed.Comment: 11 pages LaTeX, epsfig.sty + 1 PostScript figure. submitted to
Journal of Nuclear Physic
New effective interactions in RMF theory with non-linear terms and density-dependent meson-nucleon coupling
New parameter sets for the Lagrangian density in the relativistic mean field
(RMF) theory, PK1 with nonlinear sigma- and omega-meson self-coupling, PK1R
with nonlinear sigma-, omega- and rho-meson self-coupling and PKDD with the
density-dependent meson-nucleon coupling, are proposed. They are able to
provide an excellent description not only for the properties of nuclear matter
but also for the nuclei in and far from the valley of beta-stability. For the
first time in the parametrization of the RMF Lagrangian density, the
center-of-mass correction is treated by a microscopic way, which is essential
to unify the description of nuclei from light to heavy regions with one
effective interaction.Comment: 22 pages, 16 EPS figures, RevTeX
Pion photoproduction on nucleons in a covariant hadron-exchange model
We present a relativistic dynamical model of pion photoproduction on the
nucleon in the resonance region. It offers several advances over the existing
approaches. The model is obtained by extending our -scattering
description to the electromagnetic channels. The resulting photopion amplitude
is thus unitary in the , \ga N channel space, Watson's theorem is
exactly satisfied. At this stage we have included the pion, nucleon,
\De(1232)-resonance degrees of freedom. The and meson
exchanges are also included, but play a minor role in the considered energy
domain (up to GeV). In this energy range the model provides a
good description of all the important multipoles. We have allowed for only two
free parameters -- the photocouplings of the -resonance. These
couplings are adjusted to reproduce the strength of corresponding
resonant-multipoles and at the resonance position.Comment: 17 pages, 4 figs, version to appear in Phys. Rev. C 70 (2004
Deconfinement in the Quark Meson Coupling Model
The Quark Meson Coupling Model which describes nuclear matter as a collection
of non-overlapping MIT bags interacting by the self-consistent exchange of
scalar and vector mesons is used to study nuclear matter at finite temperature.
In its modified version, the density dependence of the bag constant is
introduced by a direct coupling between the bag constant and the scalar mean
field. In the present work, the coupling of the scalar mean field with the
constituent quarks is considered exactly through the solution of the Dirac
equation. Our results show that a phase transition takes place at a critical
temperature around 200 MeV in which the scalar mean field takes a nonzero value
at zero baryon density. Furthermore it is found that the bag constant decreases
significantly when the temperature increases above this critical temperature
indicating the onset of quark deconfinement.Comment: LaTeX/TeX 15 pages (zk2.tex)+ 6 figures in TeX forma
Zaburzenia w białkach kardiomiocytu przyczyną niewydolności serca
Niewydolność serca nadal stanowi znaczący problem kliniczny i ekonomiczny związany
z bardzo dużą zachorowalnością i śmiertelnością. Niewydolność serca mogą wywoływać znane
czynniki, prowadzące do powstania kardiomiopatii wtórnej lub czynniki nieznane, powodujące
kardiomiopatię pierwotną. Dzięki rozwojowi techniki molekularnej możliwe staje się określenie
przyczyn kardiomiopatii dotychczas określanych mianem pierwotnych. Jedną z takich
przyczyn są zaburzenia w obrębie białek kardiomiocytu, tworzących błonę komórkową (sarkoglikany,
dystrofina), cytoszkielet (desmina, tubulina) czy sarkomer (aktyna, miozyna, troponina
I, T, C)
Hot Nuclear Matter in the Quark Meson Coupling Model with Dilatons
We study hot nuclear matter in an explicit quark model based on a mean field
description of nonoverlapping nucleon bags bound by the self-consistent
exchange of scalar and vector mesons as well as the glueball field. The
glueball exchange as well as a realization of the broken scale invariance of
quantum chromodynamics is achieved through the introduction of a dilaton field.
The calculations also take into account the medium-dependence of the bag
constant. The effective potential with dilatons is applied to nuclear matter.
The nucleon properties at finite temperature as calculated here are found to be
appreciably different from cold nuclear matter. The introduction of the dilaton
potential improves the shape of the saturation curve at T=0 and is found to
affect hot nuclear matter significantly.Comment: LaTeX/TeX 12 pages (zak2), 13 figures in TeX forma
Reply to the Comment by B. Andresen
All the comments made by Andresen's comments are replied and are shown not to
be pertinent. The original discussions [ABE S., Europhys. Lett. 90 (2010)
50004] about the absence of nonextensive statistical mechanics with q-entropies
for classical continuous systems are reinforced.Comment: 5 pages. This is Reply to B. Andresen's Comment on the paper entitled
"Essential discreteness in generalized thermostatistics with non-logarithmic
entropy", Europhys. Lett. 90 (2010) 5000
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