10,172 research outputs found

    Three and Two Colours Finite Density QCD at Strong Coupling: A New Look

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    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

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    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

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    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

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    The Grand Canonical formalism is generally used in numerical simulations of finite density QCD since it allows free mobility in the chemical potential Ό\mu. 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

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    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

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    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