3,210 research outputs found
Gridding of near vertical unrectified space photographs
Gridding of near vertical unrectified space photograph
The Influence of Reaction Rates on the Final p-Abundances
The astrophysical p-process is responsible for the origin of the proton rich
nuclei,which are heavier than iron. A huge network involving thousands of
reaction rates is necessary to calculate the final p-abundances. But not all
rates included in the network have a strong influence on the p-nuclei
abundances. The p-process was investigated using a full nuclear reaction
network for a type II supernovae explosion when the shock front passes through
the O/Ne layer. Calculations were done with a multi-layer model adopting the
seed of a pre-explosion evolution of a 25 mass star. In extensive simulations
we investigated the impact of single reaction rates on the final p-abundances.
The results are important for the strategy of future experiments in this field.Comment: 4 page
Interpretation of Recent SPS Dilepton Data
We summarize our current theoretical understanding of in-medium properties of
the electromagnetic current correlator in view of recent dimuon data from the
NA60 experiment in In(158 AGeV)-In collisions at the CERN-SPS. We discuss the
sensitivity of the results to space-time evolution models for the hot and dense
partonic and hadronic medium created in relativistic heavy-ion collisions and
the contributions from different sources to the dilepton-excess spectra.Comment: To appear in the proceedings of the 19th International Conference on
Ultra-Relativistic Nucleus-Nucleus Collisions (Quark Matter 2006) v2:
references added, minor typos correcte
Heavy-Quark Diffusion, Flow and Recombination at RHIC
We discuss recent developments in assessing heavy-quark interaction in the
Quark-Gluon Plasma (QGP). While induced gluon radiation is expected to be the
main energy-loss mechanism for fast-moving quarks, we focus on elastic
scattering which prevails toward lower energies, evaluating both perturbative
(gluon-exchange) and nonperturbative (resonance formation) interactions in the
QGP. The latter are treated within an effective model for D- and B-meson
resonances above T_c as motivated by current QCD lattice calculations.
Pertinent diffusion and drag constants, following from a Fokker-Planck
equation, are implemented into an expanding fireball model for Au-Au collisions
at RHIC using relativistic Langevin simulations. Heavy quarks are hadronized in
a combined fragmentation and coalescence framework, and resulting
electron-decay spectra are compared to recent RHIC data. A reasonable
description of both nuclear suppression factors and elliptic flow up to momenta
of ~5 GeV supports the notion of a strongly interacting QGP created at RHIC.
Consequences and further tests of the proposed resonance interactions are
discussed.Comment: 8 pages, 14 figures, contribution to the proceedings for the
"International Conference on Strangeness in Quark Matter 2006
The Vector Probe in Heavy-Ion Reactions
We review essential elements in using the channel as a probe for
hot and dense matter as produced in (ultra-) relativistic collisions of heavy
nuclei. The uniqueness of the vector channel resides in the fact that it
directly couples to photons, both real and virtual (dileptons), enabling the
study of thermal radiation and in-medium effects on both light () and heavy () vector mesons. We emphasize the importance
of interrelations between photons and dileptons, and characterize relevant
energy/mass regimes through connections to Quark-Gluon-Plasma emission and
chiral symmetry restoration. Based on critical analysis of our current
understanding of data from fixed-target energies, we identify open key
questions to be addressed.Comment: Invited Talk at the Hot Quarks 2004 Workshop, July 18-24, 2004 (Taos
Valley, NM, USA), 15 pages latex incl 14 figs and iop style files, to appear
in the proceeding
Hadro-Chemistry and Evolution of (Anti-) Baryon Densities at RHIC
The consequences of hadro-chemical freezeout for the subsequent hadron gas
evolution in central heavy-ion collisions at RHIC and LHC energies are
discussed with special emphasis on effects due to antibaryons. Contrary to
naive expectations, their individual conservation, as implied by experimental
data, has significant impact on the chemical off-equilibrium composition of
hadronic matter at collider energies. This may reflect on a variety of
observables including source sizes and dilepton spectra.Comment: 4 pages ReVTeX incl. 3 ps-figs, submitted to PR
The Causal Structure of Emotions in Aristotle: Hylomorphism, Causal Interaction between Mind and Body, and Intentionality
Recently, a strong hylomorphic reading of Aristotelian emotions has been put forward, one that allegedly eliminates the problem of causal interaction between soul and body. Taking the presentation of emotions in de An. I 1 as a starting point and basic thread, but relying also on the discussion of Rh. II, I will argue that this reading only takes into account two of the four causes of emotions, and that, if all four of them
are included into the picture, then a causal interaction of mind and body remains within Aristotelian emotions, independent of how strongly their hylomorphism is understood. Beyond the discussion with this recent reading, the analysis proposed of the fourfold causal structure of emotions is also intended as a hermeneutical starting point for a comprehensive analysis of particular emotions in Aristotle. Through the different causes Aristotle seems to account for many aspects of the complex phenomenon of emotion, including its physiological causes, its mental causes, and its intentional object
meson broadening and dilepton production in heavy ion collisions
The modification of the width of the rho meson due to in-medium decays and
collisions is evaluated. In high temperature and/or high density hadronic
matter, the collision width is much larger than the one-loop decay width. The
large width of the meson in matter seems to be consistent with some
current interpretations of the mass spectra measured at the CERN/SPS.Comment: 4 pages, LaTeX, including 4 Postscript figures, to appear in Proc. of
QM'99, Nucl. Phys.
Medium Modification of The Pion-Pion Interaction at Finite Density
We discuss medium modifications of the unitarized pion-pion interaction in
the nuclear medium. We incorporate both the effects of chiral symmetry
restoration and the influence of collective nuclear pionic modes originating
from the p-wave coupling of the pion to delta-hole configurations. We show in
particular that the dropping of the sigma meson mass significantly enhances the
low energy structure created by the in-medium collective pionic modes.Comment: 26 pages, 7 figures included, Latex fil
Numerical solution of the color superconductivity gap in a weak coupling constant
We present the numerical solution of the full gap equation in a weak coupling
constant . It is found that the standard approximations to derive the gap
equation to the leading order of coupling constant are essential for a secure
numerical evaluation of the logarithmic singularity with a small coupling
constant. The approximate integral gap equation with a very small should be
inverted to a soft integral equation to smooth the logarithmic singularity near
the Fermi surface. The full gap equation is solved for a rather large coupling
constant . The approximate and soft integral gap equations are solved
for small values. When their solutions are extrapolated to larger
values, they coincide the full gap equation solution near the Fermi surface.
Furthermore, the analytical solution matches the numerical one up to the order
one O(1). Our results confirm the previous estimates that the gap energy is of
the order tens to 100 MeV for the chemical potential MeV. They
also support the validity of leading approximations applied to the full gap
equation to derive the soft integral gap equation and its analytical solution
near the Fermi surface.Comment: 7 pages+ 6 figs, Stanford, Frankfurt and Bethlehe
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