10,392 research outputs found
Three and Two Colours Finite Density QCD at Strong Coupling: A New Look
Simulations in finite density, beta=0 lattice QCD by means of the
Monomer-Dimer-Polymer algorithm show a signal of first order transition at
finite temporal size. This behaviour agrees with predictions of the mean field
approximation, but is difficult to reconcile with infinite mass analytical
solution. The MDP simulations are considered in detail and severe convergence
problems are found for the SU(3) gauge group, in a wide region of chemical
potential. Simulations of SU(2) model show discrepancies with MDP results as
well.Comment: 18 pages, 9 figures, to appear in Nucl. Phys.
Rigorous arguments against current wisdoms in finite density QCD
QCD at finite chemical potential is analytically investigated in the region
of large bare fermion masses. We show that, contrary to the general wisdom, the
phase of the fermion determinant is irrelevant at zero temperature. However if
the system is put at finite temperature, the contribution of the phase is
finite. We also discuss on the quenched approximation and suggest that the
origin of the failure of this approximation in finite density QCD could relay
on the fundamental role that Pauli exclusion principle plays in this case.Comment: 16 pages, 5 figure
Early computing and data processing in Malta
Malta has been a heavy user of computers only since the 1980s, following the availability of the personal computer. Before that date, the diffusion of computers in Malta was slow. This paper describes the supply and application of computers from the late 1960s until the early 1980s. The state of computing and the slow take-up of computers is analysed and explained. The paper concludes with an explanation for 'fake off' in the 1980s.peer-reviewe
Phase transition(s) in finite density QCD
The Grand Canonical formalism is generally used in numerical simulations of
finite density QCD since it allows free mobility in the chemical potential
. We show that special care has to be used in extracting numerical results
to avoid dramatic rounding effects and spurious transition signals. If we
analyze data correctly, with reasonable statistics, no signal of first order
phase transition is present and results using the Glasgow prescription are
practically coincident with the ones obtained using the modulus of the
fermionic determinant.Comment: 6 pages, 5 ps figs. To appear in Proceedings of "QCD at Finite Baryon
Density" workshop, Bielefeld, 27-30 April 199
Early telecommunication and the birth of telegraphy in Malta
This paper reviews the birth of telegraphy and its take-up in Malta before the advent of radio. The driving force behind the adoption of a number of signalling methods and the telegraph in Malta was the militia, but a means of effective communication was also important for trade and as a warning system against unwanted intruders. Foreign, diplomatic, and news correspondence became possible after submarine cables linking Malta to mainland Europe were laid in the 1860s.peer-reviewe
Ultra High Energy Cosmic Rays Propagation and Spectrum
The status of the observations of Ultra High Energy Cosmic Rays will be
reviewed, focusing on the the latest results of HiRes and Auger observatories.
A comprehensive analytical computation scheme to compute the expected UHECR
spectrum on earth will be presented, applying such scheme to interpret the
experimental results. The phenomenological scenarios favored by HiRes and Auger
in terms of chemical composition and spectrum will be also presented.Comment: 6 pages, 5 eps figures, invited review talk at the International
Symposium on the Recent Progress of Ultra High Energy Cosmic Ray Observation,
Nagoya (Japan) Dec 10-12 201
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