13,645 research outputs found
Non-Fermi Liquid Aspects of Cold and Dense QED and QCD: Equilibrium and Non-Equilibrium
Infrared divergences from the exchange of dynamically screened magnetic
gluons (photons) lead to the breakdown of the Fermi liquid description of the
{\em normal} state of cold and dense QCD and QED. We implement a resummation of
these divergences via the renormalization group to obtain the spectral density,
dispersion relation, widths and wave function renormalization of single
quasiparticles near the Fermi surface. We find that all feature scaling with
anomalous dimensions:
with \lambda = \frac{\alpha}{6\pi} ~
{for QED} \vspace{0.5 ex} ~,~ \frac{\alpha_s}{6\pi} \frac{N^2_c-1}{2N_c}
\~~{for QCD with}. The discontinuity of the distribution function for
quasiparticles near the Fermi surface vanishes. The dynamical renormalization
group is implemented to study the relaxation of quasiparticles in real time.
Quasiparticles with Fermi momentum have vanishing group velocity and relax with
a power law with a coupling dependent anomalous dimension.Comment: 39 pages, 2 figure
Primordial Magnetic Fields from Out of Equilibrium Cosmological Phase Transitions
The universe cools down monotonically following its expansion.This generates
a sequence of phase transitions. If a second order phase transition happens
during the radiation dominated era with a charged order parameter, spinodal
unstabilities generate large numbers of charged particles. These particles
hence produce magnetic fields.We use out of equilibrium field theory methods to
study the dynamics in a mean field or large N setup.The dynamics after the
transition features two distinct stages: a spinodal regime dominated by linear
long wave length instabilities, and a scaling stage in which the
non-linearities and backreaction of the scalar fields are dominant. This second
stage describes the growth of horizon sized domains. We implement a formulation
based on the non equilibrium Schwinger-Dyson equations to obtain the spectrum
of magnetic fields that includes the dissipative effects of the plasma. We find
that large scale magnetogenesis is efficient during the scaling regime. Charged
scalar field fluctuations with wavelengths of the order of the Hubble radius
induce large scale magnetogenesis via loop effects.The leading processes
are:pair production, pair annihilation and low energy bremsstrahlung, these
processes while forbidden in equilibrium are allowed strongly out of
equilibrium. The ratio between the energy density on scales larger than L and
that in the background radiation r(L,T)= rho_B(L,T)/rho_{cmb}(T) is r(L,T) ~
10^{-34} at the Electroweak scale and r(L,T) ~ 10^{-14} at the QCD scale for L
sim 1 Mpc. The resulting spectrum is insensitive to the magnetic diffusion
length and equipartition between electric and magnetic fields does not hold. We
conjecture that a similar mechanism could be operative after the QCD chiral
phase transition.Comment: 11 pages, no figures. Lecture given at the International Conference
Magnetic Fields in the Universe, Angra dos Reis, Brazil, November, 200
Web based system architecture for long pulse remote experimentation
Remote experimentation (RE) methods will be essential in next generation fusion devices. Requirements for long pulse RE will be: on-line data visualization, on-line data acquisition processes monitoring and on-line data acquisition systems interactions (start, stop or set-up modifications). Note that these methods are not oriented to real-time control of fusion plant devices.
INDRA Sistemas S.A., CIEMAT (Centro de Investigaciones Energéticas Medioambientales y Tecnológicas) and UPM (Universidad Politécnica de Madrid) have designed a specific software architecture for these purposes. The architecture can be supported on the BeansNet platform, whose integration with an application server provides an adequate solution to the requirements. BeansNet is a JINI based framework developed by INDRA, which makes easy the implementation of a remote experimentation model based on a Service Oriented Architecture. The new software architecture has been designed on the basis of the experience acquired in the development of an upgrade of the TJ-II remote experimentation system
Phase behavior of (CO2 + H-2) and (CO2+ N-2) at temperatures between (218.15 and 303.15)K at pressures up to 15 MPa
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