6,134 research outputs found
An overview of the communications technology satellite project: Executive summary
An overview of the Communications Technology Satellite (CTS) project, a joint venture between NASA and the Canadian Department of Communications is given. A brief technical description of the CTS spacecraft and its cognate hardware and operations, a history of the CTS project, and a list of the CTS experiments and demonstrations conducted during the course of the project are given
Theory and Phenomenology of Vector Mesons in Medium
Electromagnetic probes promise to be direct messengers of (spectral
properties of) hot and dense matter formed in heavy-ion collisions, even at
soft momentum transfers essential for characterizing possible phase
transitions. We examine how far we have progressed toward this goal by
highlighting recent developments, and trying to establish connections between
lattice QCD, effective hadronic models and phenomenology of dilepton
production.Comment: 8 pages latex incl. 12 ps/eps files; invited plenary talk at Quark
Matter 2006 conference, Shanghai (China), Nov. 14-20, 200
Heavy-Quark Probes of the Quark-Gluon Plasma at RHIC
Thermalization and collective flow of charm (c) and bottom (b) quarks in
ultra-relativistic heavy-ion collisions are evaluated based on elastic parton
rescattering in an expanding quark-gluon plasma (QGP). We show that resonant
interactions in a strongly interacting QGP (sQGP), as well as the effects of
parton coalescence, can play an essential role in the interpretation of recent
data from the Relativistic Heavy-Ion Collider (RHIC), and thus illuminate the
nature of the sQGP and its hadronization. Our main assumption, motivated by
recent findings in lattice computations of Quantum Chromodynamics, is the
existence of D- and B-meson states in the sQGP, providing resonant cross
sections for heavy quarks up to temperatures of sim 2 T_c. Pertinent drag and
diffusion coefficients are implemented into a relativistic Langevin simulation
to compute transverse-momentum spectra and azimuthal asymmetries (v_2) of b-
and c-quarks in Au-Au collisions at RHIC. Hadronization into D- and B-mesons is
calculated from a combination of coalescence with light quarks and
fragmentation, and associated electron-decay spectra and v_2 are compared to
recent RHIC data. We also comment on the relative importance of radiative and
elastic energy loss of heavy quarks in the QGP.Comment: 4 pages, 3 figures, v2: 1 reference updated, v3: replaced comparison
to data to more recent data, references added, contents unchange
Theory and Phenomenology of Heavy Flavor at RHIC
We review the problem of heavy-quark diffusion in the Quark-Gluon Plasma and
its ramifications for heavy-quark spectra in heavy-ion collisions at RHIC. In
particular, we attempt to reconcile underlying mechanisms of several seemingly
different approaches that have been put forward to explain the large
suppression and elliptic flow of non-photonic electron spectra. We also
emphasize the importance of a quantitative description of the bulk medium
evolution to extract reliable values for the heavy-quark diffusion coefficient.Comment: 8 pages latex, including 10 eps figures; plenary talk at SQM08,
Beijing (China), Oct. 06-10, 200
Instanton-Induced Interactions in Finite Density QCD
We consider the finite density, zero-temperature behaviour of quark matter in
the instanton picture. Since the instanton-induced interactions are attractive
in both and channels, a competition ensues between phases of
matter with condensation in either or both. It results in chiral symmetry
restoration due to the onset of diquark condensation, a `colour
superconductor', at finite density.Comment: 4 pages, 5 figures, uses espcrc1.sty. To appear in Proceedings of
Quark Matter 99 (10-14 May 1999, Torino, Italy) and PANIC 99 (10-16 June
1999, Uppsala, Sweden
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