1,456 research outputs found
Properties of the phi meson at high temperatures and densities
We calculate the spectral density of the phi meson in a hot bath of nucleons
and pions using a general formalism relating self-energy to the forward
scattering amplitude (FSA). In order to describe the low energy FSA, we use
experimental data along with a background term. For the high energy FSA, a
Regge parameterization is employed. We verify the resulting FSA using
dispersion techniques. We find that the position of the peak of the spectral
density is slightly shifted from its vacuum position and that its width is
considerably increased. The width of the spectral density at a temperature of
150 MeV and at normal nuclear density is more than 90 MeV.Comment: 4 pages, 5 figures, Poster presented at Quark Matter 200
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
Dileptons from the strongly-interacting Quark-Gluon Plasma within the Parton-Hadron-String-Dynamics (PHSD) approach
Dilepton production in In+In collisions at 158 AGeV is studied within the
microscopic Parton-Hadron-Strings Dynamics (PHSD) transport approach, which is
based on a dynamical quasiparticle model (DQPM) matched to reproduce lattice
QCD results in thermodynamic equilibrium. A comparison to the data of the NA60
Collaboration shows that the low mass dilepton spectra are well described by
including a collisional broadening of vector mesons, while the spectra in the
intermediate mass range are dominated by off-shell quark-antiquark annihilation
in the nonperturbative QGP. In particular, the observed softening of the mT
spectra at intermediate masses is reproduced.Comment: talk given at the 21st International Conference on Ultra-Relativistic
Nucleus-Nucleus Collisions (Quark Matter 2009), to be published in
Nucl.Phys.A, 4 pages, 3 figures, elsarticle styl
Partonic Scattering Cross Sections in the QCD Medium
A medium modified gluon propagator is used to evaluate the scattering cross section for the process gg-->gg in the QCD medium by performing an explicit sum over the polarizations of the gluons. We incorporate a magnetic sreening mass from a non-perturbative study. It is shown that the medium modified cross section is finite, divergence free, and is independent of any ad-hoc momentum transfer cut-off parameters. The medium modified finite cross sections are necessary for a realistic investigation of the production and equilibration of the minijet plasma expected at RHIC and LHC
Electrical control of inter-dot electron tunneling in a quantum dot molecule
We employ ultrafast pump-probe spectroscopy to directly monitor electron
tunneling between discrete orbital states in a pair of spatially separated
quantum dots. Immediately after excitation, several peaks are observed in the
pump-probe spectrum due to Coulomb interactions between the photo-generated
charge carriers. By tuning the relative energy of the orbital states in the two
dots and monitoring the temporal evolution of the pump-probe spectra the
electron and hole tunneling times are separately measured and resonant
tunneling between the two dots is shown to be mediated both by elastic and
inelastic processes. Ultrafast (< 5 ps) inter-dot tunneling is shown to occur
over a surprisingly wide bandwidth, up to ~8 meV, reflecting the spectrum of
exciton-acoustic phonon coupling in the system
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