29,438 research outputs found
D Mesons in Nuclear Matter: A DN Coupled-Channel Equations Approach
A set of coupled two-body scattering equations is solved for the DN system
embedded in an iso-symmetric nuclear matter. The in-medium behavior of charmed
D mesons: (D^+,D^0), is investigated from the self-consistent solution within
this scheme. The effective meson-baryon Lagrangian in charm quantum number one
sector, the key ingredient in the present study, is adopted from a recent model
by Hofmann and Lutz which has aimed at combining the charmed meson degree of
freedom in a consistent manner with chiral unitary models. After a critical
examination, the original model is modified in several important aspects, such
as the method of regularization, in order to be more consistent and practical
for our objective. The resultant interaction is used to reproduce the position
and width of the s-wave \Lambda_c(2593) resonance in the isospin zero DN
channel. In the isospin one channel, it generates a rather wide resonance at
\~2770 MeV. The corresponding in-medium solution is then sought by
incorporating Pauli blocking and the D- and \pi-meson dressing
self-consistently. At normal nuclear matter density, the resultant \Lambda_c
(2593) is found to stay narrow and shifted at a lower energy, while the I=1
resonance is lowered in position as well and broadened considerably. The
possible implication of our findings on the J/\Psi suppression, etc. in
relativistic heavy ion collisions is briefly discussed.Comment: 30 pages, 8 eps figures, some typos and coefficients corrected,
published in Phys. Rev.
Finite temperature effects on the antikaon optical potential
By solving the Bethe-Goldstone equation, we have obtained the
optical potential from the effective interaction in nuclear matter
at T=0. We have extended the model by incorporating finite temperature effects
in order to adapt our calculations to the experimental conditions in heavy-ion
collisions. In the rank of densities (), the finite temperature
optical potential shows a smooth behaviour if we compare it to the
T=0 outcome. Our model has also been applied to the study of the ratio between
and produced at GSI with around 70 MeV. Our results point at
the necessity of introducing an attractive optical potential.Comment: 7 pages, 4 figures. Contribution to the proceedings of Mesons & Light
Nuclei '01 (2-6th July, Prague
K- absorption in nuclei by two and three nucleons
It will be shown that the peaks in the (Lambda p) and (Lambda d) invariant
mass distributions, observed in recent FINUDA experiments and claimed to be
signals of deeply bound kaonic states, are naturally explained in terms of K-
absorption by two or three nucleons leaving the rest of the original nuclei as
spectator. For reactions on heavy nuclei, the subsequent interactions of the
particles produced in the primary absorption process with the residual nucleus
play an important role. Our analyses leads to the conclusion that at present
there is no experimental evidence of deeply bound K- state in nuclei. Although
the FINUDA experiments have been done for reasons which are not supported a
posteriori, some new physics can be extracted from the data.Comment: 6 pages, 5 figures. Talk presented at the International Conference on
Exotic Atoms "EXA 2008", Vienna, Austria, September 15-18, 200
Latest results for the antikaon-nucleon optical potential
The key question of this letter is whether the K-nucleus optical potential is
deep, as it is prefered by the phenomenological fits to kaonic atoms data, or
shallow, as it comes out from unitary chiral model calculations. The current
experimental situation is reviewed.Comment: 3 pages, 1 figure. Presented at the 21st European Conference on the
Few-Body problems in Physics (EFB21), Salamanca, Spain, August 29 - September
3, 201
Kinetic Ising System in an Oscillating External Field: Stochastic Resonance and Residence-Time Distributions
Experimental, analytical, and numerical results suggest that the mechanism by
which a uniaxial single-domain ferromagnet switches after sudden field reversal
depends on the field magnitude and the system size. Here we report new results
on how these distinct decay mechanisms influence hysteresis in a
two-dimensional nearest-neighbor kinetic Ising model. We present theoretical
predictions supported by numerical simulations for the frequency dependence of
the probability distributions for the hysteresis-loop area and the
period-averaged magnetization, and for the residence-time distributions. The
latter suggest evidence of stochastic resonance for small systems in moderately
weak oscillating fields.Comment: Includes updated results for Fig.2 and minor text revisions to the
abstract and text for clarit
Towards a new determination of the QCD Lambda parameter from running couplings in the three-flavour theory
We review our new strategy and current status towards a high precision
computation of the Lambda parameter from three-flavour simulations in QCD. To
reach this goal we combine specific advantages of the Schr\"odinger functional
and gradient flow couplings.Comment: 7 pages, 3 figures; Proceedings of the 32nd International Symposium
on Lattice Field Theory; 23-28 June, 2014, Columbia University, New Yor
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