2,389 research outputs found
The Coester Line in Relativistic Mean Field Nuclear Matter
The Walecka model contains essentially two parameters that are associated
with the Lorentz scalar (S) and vector (V) interactions. These parameters are
related to a two-body interaction consisting of S and V, imposing the condition
that the two-body binding energy is fixed. We have obtained a set of different
values for the nuclear matter binding energies at equilibrium densities. We
investigated the existence of a linear correlation between and ,
claimed to be universal for nonrelativistic systems and usually known as the
Coester line, and found an approximate linear correlation only if remains
constant. It is shown that the relativistic content of the model, which is
related to the strength of , is responsible for the shift of the Coester
line to the empirical region of nuclear matter saturation.Comment: 7 pages, 5 figure
Four-boson scale near a Feshbach resonance
We show that an independent four-body momentum scale drives the
tetramer binding energy for fixed trimer energy (or three-body scale
) and large scattering length (). The three- and four-body forces
from the one-channel reduction of the atomic interaction near a Feshbach
resonance disentangle and . The four-body independent
scale is also manifested through a family of Tjon-lines, with slope given by
for . There is the possibility of a new
renormalization group limit cycle due to the new scale
Phase transition of the nucleon-antinucleon plasma at different ratios
We investigate phase transitions for the Walecka model at very high
temperatures. As is well known, depending on the parametrization of this model
and for the particular case of a zero chemical potential (), a first
order phase transition is possible \cite{theis}. We investigate this model for
the case in which . It turns out that, in this situation, phases
with different values of antinucleon-nucleon ratios and net baryon densities
may coexist. We present the temperature versus antinucleon-nucleon ratio as
well as the temperature versus the net baryon density for the coexistence
region. The temperature versus chemical potential phase diagram is also
presented.Comment: 5 pages, 8 figure
Nucleon-nucleon scattering within a multiple subtractive renormalization approach
A methodology to renormalize the nucleon-nucleon interaction, using a
recursive multiple subtraction approach to construct the kernel of the
scattering equation, is presented. We solve the subtracted scattering equation
with the next-leading-order (NLO) and next-to-next-leading-order (NNLO)
interactions. The results are presented for all partial waves up to ,
fitted to low-energy experimental data. In our renormalizaton group invariant
method, when introducing the NLO and NNLO interactions, the subtraction energy
emerges as a renormalization scale and the momentum associated with it comes to
be about the QCD scale (), irrespectively to the partial wave.Comment: Final versio
Form factors in the Bullough-Dodd related models: The Ising model in a magnetic field
We consider particular modification of the free-field representation of the
form factors in the Bullough-Dodd model. The two-particles minimal form factors
are excluded from the construction. As a consequence, we obtain convenient
representation for the multi-particle form factors, establish recurrence
relations between them and study their properties. The proposed construction is
used to obtain the free-field representation of the lightest particles form
factors in the perturbed minimal models. As a significant example
we consider the Ising model in a magnetic field. We check that the results
obtained in the framework of the proposed free-field representation are in
agreement with the corresponding results obtained by solving the bootstrap
equations.Comment: 20 pages; v2: some misprints, textual inaccuracies and references
corrected; some references and remarks adde
Isospin Constraints on the Parametric Coupling Model for Nuclear Matter
We make use of isospin constraints to study the parametric coupling model and
the properties of asymmetric nuclear matter. Besides the usual constraints for
nuclear matter - effective nucleon mass and the incompressibility at saturation
density - and the neutron star constraints - maximum mass and radius - we have
studied the properties related with the symmetry energy. These properties have
constrained to a small range the parameters of the model. We have applied our
results to study the thermodynamic instabilities in the liquid-gas phase
transition as well as the neutron star configurations.Comment: 11 pages, 10 figure
Integrable structures in LGTs near the deconfinement transition
In this contribution we review some recent results about the emergence of 2D
integrable systems in 3D Lattice Gauge Theories near the deconfinement
transition. We focus on some concrete examples involving the flux tube
thickness, the ratio of k-string tensions and Polyakov loops correlators in
various models.Comment: 8 pages, Poster contribution to the XXVII International Symposium on
Lattice Field Theory, July 26-31, 2009, Peking University, Beijing, Chin
Naturalistic study on the effectiveness of psycho-oncological interventions in cancer patients and their partners
Background: There is evidence for the efficacy of psycho-oncological interventions (POI) in randomized controlled trials for cancer patients. Our objective was to explore, under naturalistic conditions (using propensity score matching), whether POI are effective to decrease anxiety, depression, distress and overall psychopathological symptoms within cancer patients and their partners. Methods: This study was conducted in the Oncology and Hematology Center of a University clinic in Switzerland with a group of 186 patients and 117 partners. Outcome measures of mental health were the Hospital Anxiety and Depression Scale and the Symptom Checklist (SCL-9-K). Repeated-measures ANOVAs were used to analyze change over time and group effects between individuals with POI vs. without POI. Results: Highly distressed patients and their partners participating in POI reported better mental health over time. Among moderately distressed patients, a decrease over time emerged in depression and distress independent of POI. No effectiveness of POI could be demonstrated in moderately distressed patients and partners. Conclusion: Most of the highly distressed patients receive additional POI and therefore conclusions about the efficacy of POI are difficult. For moderately distressed individuals, POI as implemented in Switzerland does not improve mental health in such patients and their partners, which may be caused by very time limited POI treatments. Studies with more intense POI treatments are neede
- …