49 research outputs found
D-mesons in dense nuclear matter
The D-meson properties in dense nuclear matter are studied. The D-meson
spectral density is obtained within the framework of a coupled-channel
self-consistent calculation assuming, as bare meson-baryon interaction, a
separable potential. The resonance is generated dynamically
in our coupled-channel model. The medium modifications of the D-meson
properties due to Pauli blocking and the dressing of D-mesons, nucleons and
pions are also studied. We conclude that the self-consistent coupled-channel
process reduces the in-medium effects on the D-meson compared to previous
literature which do not considered the coupled-channel structureComment: 4 pages, 4 figures, to appear in the proceedings of Hard Probes 2004,
Ericeira, Portugal, November 4-10, 2004 (European Physical Journal C
D-mesons: In-medium effects at FAIR
The -meson spectral density at finite temperature is obtained within a
self-consistent coupled-channel approach. For the bare meson-baryon
interaction, a separable potential is taken, whose parameters are fixed by the
position and width of the resonance. The quasiparticle peak
stays close to the free -meson mass, indicating a small change in the
effective mass for finite density and temperature. Furthermore, the spectral
density develops a considerable width due to the coupled-channel structure. Our
results indicate that the medium modifications for the -mesons in
nucleus-nucleus collisions at FAIR (GSI) will be dominantly on the width and
not, as previously expected, on the mass.Comment: 18 pages, 3 figures, revised version accepted for publication in
Phys. Lett.
Chiral approach to antikaon s- and p-wave interactions in dense nuclear matter
The properties of the antikaons in nuclear matter are investigated from a
chiral unitary approach which incorporates the s- and p-waves of the interaction. To obtain the in-medium meson-baryon amplitudes we include,
in a self-consistent way, Pauli blocking effects, meson self-energies corrected
by nuclear short-range correlations and baryon binding potentials. We pay
special attention to investigating the validity of the on-shell factorization,
showing that it cannot be applied in the evaluation of the in-medium
corrections to the p-wave amplitudes. In nuclear matter at saturation energy,
the and develop an attractive potential of about -30 MeV,
while the pole remains at the free space value although its width
gets sensibly increased to about 80 MeV. The antikaon also develops a moderate
attraction that does not support the existence of very deep and narrow bound
states, confirming the findings of previous self-consistent calculations.Comment: 29 pages, 12 figures, published in Physical Review
meson in dense matter
We study the properties of mesons in nuclear matter using a
unitary approach in coupled channels within the framework of the local hidden
gauge formalism and incorporating the decay channel in matter. The
in-medium interaction accounts for Pauli blocking effects and
incorporates the self-energy in a self-consistent manner. We also
obtain the (off-shell) spectral function and analyze its behaviour
at finite density and momentum. At normal nuclear matter density, the meson feels a moderately attractive potential while the width
becomes five times larger than in free space. We estimate the transparency
ratio of the reaction, which we propose as
a feasible scenario at present facilities to detect the changes of the
properties of the meson in the nuclear medium.Comment: 26 pages, 9 figures, one new section added, version published in
Phys. ReV. C, http://link.aps.org/doi/10.1103/PhysRevC.82.04521
K^-/K^+ ratio at GSI in hot and dense matter
The ratio in heavy-ion collisions at GSI energies is studied
including the properties of the participating hadrons in hot and dense matter.
The determination of the temperature and chemical potential at freeze-out
conditions compatible with the ratio is very delicate, and depends on
the approach adopted for the antikaon self-energy. Three approaches for the
self-energy are considered: non-interacting , on-shell self-energy
and single-particle spectral density. With respect to the on-shell approach,
the use of an energy dependent spectral density, including both s-
and p-wave components of the interaction, lowers considerably the
freeze-out temperature and gives rise to the "broad-band equilibration"
advocated by Brown, Rho and Song.Comment: 8 pages, 5 figures, talk given at the Strange Quark Matter
Conference, Atlantic Beach, North Carolina, March 12-17, 200
Open-charm enhancement at FAIR?
We have calculated the D-meson spectral density at finite temperature within
a self-consistent coupled-channel approach that generates dynamically the
(2593) resonance. We find a small mass shift for the D-meson in
this hot and dense medium while the spectral density develops a sizeable width.
The reduced attraction felt by the D-meson in hot and dense matter together
with the large width observed have important consequences for the D-meson
production in the future CBM experiment at FAIR.Comment: 4 pages, 2 figures, to appear in the proceedings of 9th International
Conference on Strangeness in Quark Matter (SQM2006), Los Angeles, USA, March
26-31, 200
Open charm meson in nuclear matter at finite temperature beyond the zero range approximation
The properties of open charm mesons, , , and in
nuclear matter at finite temperature are studied within a self-consistent
coupled-channel approach. The interaction of the low lying pseudoscalar mesons
with the ground state baryons in the charm sector is derived from a -channel
vector-exchange model. The in-medium scattering amplitudes are obtained by
solving the Lippmann-Schwinger equation at finite temperature including Pauli
blocking effects, as well as , , and self-energies
taking their mutual influence into account. We find that the in-medium
properties of the meson are affected by the -meson self-energy through
the intermediate loops coupled to states. Similarly, dressing the
meson in the loops has an influence over the properties of
the meson.Comment: 23 pages, 9 figures, 2 table
Energy weighted sum rules for mesons in hot and dense matter
We study energy weighted sum rules of the pion and kaon propagator in nuclear
matter at finite temperature. The sum rules are obtained from matching the
Dyson form of the meson propagator with its spectral Lehmann representation at
low and high energies. We calculate the sum rules for specific models of the
kaon and pion self-energy. The in-medium spectral densities of the K and anti-K
mesons are obtained from a chiral unitary approach in coupled channels which
incorporates the S- and P-waves of the kaon-nucleon interaction. The pion
self-energy is determined from the P-wave coupling to particle-hole and
Delta-hole excitations, modified by short range correlations. The sum rules for
the lower energy weights are fulfilled satisfactorily and reflect the
contributions from the different quasi-particle and collective modes of the
meson spectral function. We discuss the sensitivity of the sum rules to the
distribution of spectral strength and their usefulness as quality tests of
model calculations.Comment: 19 pages, 6 figures; one figure added, enhanced discussion, version
to appear in PR
Properties of D-mesons in nuclear matter within a self-consistent coupled-channel approach
The spectral density of the -meson in the nuclear environment is studied
within a self-consistent coupled-channel approach assuming a separable
potential for the bare meson-baryon interaction. The interaction,
described through a G-matrix, generates dynamically the (2593)
resonance. This resonance is the charm counterpart of the (1405)
resonance generated from the s-wave interaction in the I=0 channel.
The medium modification of the D-meson spectral density due to the Pauli
blocking of intermediate states as well as due to the dressing of the D-mesons,
nucleons and pions is investigated. We observe that the inclusion of
coupled-channel effects and the self-consistent dressing of the -meson
results in an overall reduction of the in-medium -meson changes compared to
previous work which neglect those effects.Comment: 23 pages, 10 figures, submitted for publicatio
Antikaon production in A+A collisions at SIS energies within an off-shell G-matrix approach
The production and propagation of antikaons -- described by dynamical
spectral functions as evaluated from a coupled channel
-matrix approach -- is studied for nucleus-nucleus collisions at SIS
energies in comparison to the conventional quasi-particle limit and the
available experimental data using off-shell transport theory. We find that the
spectra for and at 1.8 AGeV
remain underestimated in the -matrix approach as in the on-shell
quasi-particle approximation whereas the preliminary spectra for at
1.5 AGeV are well described in both limits. This also holds
approximately for the rapidity distributions in semi-central collisions
of at 1.93 AGeV. However, in all limits considered there is no
convincing description of all spectra simultaneously. Our off-shell transport
calculations, furthermore, demonstrate that the strongest in-medium effects
should be found for low antikaon momenta in the center-of-mass frame, since the
deceleration of the antikaons in the attractive Coulomb and nuclear potentials
and the propagation to the on-shell mass induces a net shift and squeezing of
the spectra to the low momentum regime.Comment: 44 pages, including 18 eps figures, to be published in Nucl. Phys.