Regensburg 2007 – wissenschaftliches Programm

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DY: Fachverband Dynamik und Statistische Physik

DY 21: Finite size effects at phase transitions II (session accompanying the symposium of the same name)

DY 21.3: Vortrag

Mittwoch, 28. März 2007, 14:30–14:45, H3

High precision Monte Carlo analysis of tails for the order-parameter distribution of the two-dimensional Ising model — •Rudolf Hilfer¹, Bibudhananda Biswal¹, Hans-Georg Mattutis², and Wolfhard Janke³ — ¹ICP, Universitaet Stuttgart, Pfaffenwaldring 27, 70569 Stuttgart, Germany — ²Tokyo University of Electro-communications, Dept. of Mechanical and Control Engineering, Chofu, Tokyo 182-8585, Japan — ³Institut für Theoretische Physik, Universität Leipzig, Augustusplatz 10/11, D-04109 Leipzig, Germany

The tails of the critical order-parameter distribution of the two-dimensional Ising model have been investigated through extensive multicanonical Monte Carlo simulation. Results for fixed boundary conditions are reported here, and compared with known results for periodic boundary conditions. Clear numerical evidence for ``fat'' stretched exponential tails exists below the critical temperature, indicating the possible presence of fat tails at the critical temperature. Our results suggest that, contrary to common belief, the true order parameter distribution at the critical temperature must be considered to be unknown at present.