825,537 research outputs found

    Final State Correlations at LEP 2: Bose-Einstein Correlations and the W Mass

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    Recent experimental results on Bose-Einstein correlations are presented. Emphasis will be put on the measurement of between-W correlations in WW events at LEP 2.Comment: 4 pages, 6 figures, presented at EPS HEP2003, Aachen, July 200

    Top Physics at the LHC

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    The LHC will be a top quark factory. In this note, the central role of the top quark for LHC physics will be discussed, and an overview will be given of the studies of top quark properties in preparation, with an emphasis on the systematic uncertainties that will dominate most measurements.Comment: 6 pages, 8 figures. Contribution to the proceedings of Heavy Quarks and Leptons, Melbourne, 200

    A characterization of the scientific impact of Brazilian institutions

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    In this paper we studied the research activity of Brazilian Institutions for all sciences and also their performance in the area of physics between 1945 and December 2008. All the data come from the Web of Science database for this period. The analysis of the experimental data shows that, within a nonextensive thermostatistical formalism, the Tsallis \emph{q}-exponential distribution N(c)N(c) can constitute a new characterization of the research impact for Brazilian Institutions. The data examined in the present survey can be fitted successfully by applying a universal curve namely, N(c)∝1/[1+(q−1)c/T]1q−1N(c) \propto 1/[1+(q-1) c/T]^{\frac{1}{q-1}} with q≃4/3q\simeq 4/3 for {\it all} the available citations cc, TT being an "effective temperature". The present analysis ultimately suggests that via the "effective temperature" TT, we can provide a new performance metric for the impact level of the research activity in Brazil, taking into account the number of the publications and their citations. This new performance metric takes into account the "quantity" (number of publications) and the "quality" (number of citations) for different Brazilian Institutions. In addition we analyzed the research performance of Brazil to show how the scientific research activity changes with time, for instance between 1945 to 1985, then during the period 1986-1990, 1991-1995, and so on until the present. Finally, this work intends to show a new methodology that can be used to analyze and compare institutions within a given country.Comment: 7 pages, 5 figure

    Towards a controlled study of the QCD critical point

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    The phase diagram of QCD, as a function of temperature T and quark chemical potential mu, may contain a critical point (mu_E,T_E) whose non-perturbative nature makes it a natural object of lattice studies. However, the sign problem prevents the application of standard Monte Carlo techniques at non-zero baryon density. We have been pursuing an approach free of the sign problem, where the chemical potential is taken as imaginary and the results are Taylor-expanded in mu/T about mu=0, then analytically continued to real mu. Within this approach we have determined the sensitivity of the critical chemical potential mu_E to the quark mass, d(\mu_E)^2/dm_q|_{\mu_E=0}. Our study indicates that the critical point moves to {\em smaller} chemical potential as the quark mass {\em increases}. This finding, contrary to common wisdom, implies that the deconfinement crossover, which takes place in QCD at mu=0 when the temperature is raised, will remain a crossover in the mu-region where our Taylor expansion can be trusted. If this result, obtained on a coarse lattice, is confirmed by simulations on finer lattices now in progress, then we predict that no {\em chiral} critical point will be found for mu_B \lesssim 500 MeV, unless the phase diagram contains additional transitions.Comment: 4 pages, 6 figures, proceedings of Quark Matter 2008, Jaipur (India), Feb. 2008, to appear in J. Phys.

    Simulating Male Selfish Strategy in Reproduction Dispute

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    We introduce into the Penna Model for biological ageing one of the possible male mechanisms used to maximize the ability of their sperm to compete with sperm from other males. Such a selfish mechanism increases the male reproduction success but may decrease the survival probability of the whole female population, depending on how it acts. We also find a dynamic phase transition induced by the existence of an absorbing state where no selfish males survive.Comment: 7 pages, latex including 2 eps figure
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