2,345 research outputs found
Dynamical screening in hot systems away from (chemical) equilibrium
Within the Closed Time Path Formalism of Thermal Field Theory we calculate
the hard photon emission rate as well as the collisional energy-loss rate for a
quark-gluon plasma away from chemical equilibrium. Mass singularities are shown
to be dynamically screened within HTL-resummed perturbation theory also away
from equilibrium. Additional (pinch) singularities are absent and well defined
results are obtained.Comment: Talk given at the Japanese Workshop on Thermal Quantum Field Theories
and their Applications, Kyoto, Japan, 25.-27. August 1999, 6 page
Dynamical screening away from equilibrium: hard photon production and collisional energy loss
We investigate the production rate for hard real photons and the collisional
energy loss in the quark-gluon plasma away from chemical equilibrium. Applying
the Hard-Thermal-Loop resummation scheme away from equilibrium, we can show
that Landau damping provides dynamical screening for both fermion and boson
exchange present in the two quantities.Comment: 5 pages RevTeX, 2 figures, remarks for clarification and one
reference added, typos correcte
Simulation of inhomogeneous distributions of ultracold atoms in an optical lattice via a massively parallel implementation of nonequilibrium strong-coupling perturbation theory
We present a nonequilibrium strong-coupling approach to inhomogeneous systems
of ultracold atoms in optical lattices. We demonstrate its application to the
Mott-insulating phase of a two-dimensional Fermi-Hubbard model in the presence
of a trap potential. Since the theory is formulated self-consistently, the
numerical implementation relies on a massively parallel evaluation of the
self-energy and the Green's function at each lattice site, employing thousands
of CPUs. While the computation of the self-energy is straightforward to
parallelize, the evaluation of the Green's function requires the inversion of a
large sparse matrix, with . As a crucial ingredient,
our solution heavily relies on the smallness of the hopping as compared to the
interaction strength and yields a widely scalable realization of a rapidly
converging iterative algorithm which evaluates all elements of the Green's
function. Results are validated by comparing with the homogeneous case via the
local-density approximation. These calculations also show that the
local-density approximation is valid in non-equilibrium setups without mass
transport.Comment: 14 pages, 9 figure
Resonant decay of parity odd bubbles in hot hadronic matter
We investigate the decay of metastable states with broken CP-symmetry which
have recently been proposed by Kharzeev, Pisarski and Tytgat to form in hot
hadronic matter. We consider the efficiency of the amplification of the
-field via parametric resonance, taking the backreaction into account.
For times of the order , we find a particle density of about
and a correlation length of . The
corresponding momentum spectra show a non-thermal behaviour.Comment: 11 pages latex file with 4 gif - figures. Uses elsart.cls (included
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Churches Partnering Together : Biblical Strategies for Fellowship, Evangelism, and Compassion
Most churches in the United States have fewer than 75 members. Many of these congregations barely have enough money to pay their pastor’s salary, let alone launch a movement or host a conference. How can they hope to make an impact beyond their own walls?
In Churches Partnering Together, Chris Bruno and Matt Dirks show how all churches—big and small—can do more together than they can do apart. Looking to the New Testament for guidance, this practical book will help pastors, church leaders, and laypeople alike think creatively about gospel-driven church partnerships in their own communities and around the world.https://digitalcommons.cedarville.edu/faculty_books/1177/thumbnail.jp
IDeF-X ASIC for Cd(Zn)Te spectro-imaging systems
Joint progresses in Cd(Zn)Te detectors, microelectronics and interconnection
technologies open the way for a new generation of instruments for physics and
astrophysics applications in the energy range from 1 to 1000 keV. Even working
between -20 and 20 degrees Celsius, these instruments will offer high spatial
resolution (pixel size ranging from 300 x 300 square micrometers to few square
millimeters), high spectral response and high detection efficiency. To reach
these goals, reliable, highly integrated, low noise and low power consumption
electronics is mandatory. Our group is currently developing a new ASIC detector
front-end named IDeF-X, for modular spectro-imaging system based on the use of
Cd(Zn)Te detectors. We present here the first version of IDeF-X which consists
in a set of ten low noise charge sensitive preamplifiers (CSA). It has been
processed with the standard AMS 0.35 micrometer CMOS technology. The CSA are
designed to be DC coupled to detectors having a low dark current at room
temperature. The various preamps implemented are optimized for detector
capacitances ranging from 0.5 up to 30 pF.Comment: 8 pages, 11 figures, IEEE NSS-MIC conference in Rome 2004, submitted
to IEEE TNS, correction in unit of figure
Photon and Dilepton Production from Hot Out-Off-Equilibrium Media
The electromagnetic emissivity from QCD media away from equilibrium is
studied in the framework of closed time path thermal field theory. For the
dilepton rate a nonequilibrium mesonic medium is considered applying finite
temperature perturbation theory for interactions. The dilepton rate
is derived up to the order . For hard photon production a quark gluon
plasma is assumed and calculations are performed in leading order in the strong
coupling constant. These examples are chosen in order to investigate the role
of possible pinch terms in boson and in fermion propagators, respectively. The
implications of the results for phenomenology are also discussed.Comment: 16 pages LaTeX, 11 figures using epsfig. To be published in the
proceedings of the XXXVII-th Cracow School of Theoretical Physics, Dynamics
of Strong Interactions, Zakopane, June 199
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