Regensburg 2007 – wissenschaftliches Programm
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DY: Fachverband Dynamik und Statistische Physik
DY 3: Critical phenomena and phase transitions
DY 3.2: Vortrag
Montag, 26. März 2007, 12:15–12:30, H2
Improved Borel summation of critical exponents and amplitude ratios of the d=3, n=2 universality class — •Daniel Cremer and Volker Dohm — Institut für Theoretische Physik, RWTH Aachen
Borel summations are performed for the critical exponents α and γ of the d=3, n=2 universality class on the basis of seven-loop perturbation series of the ϕ4 field theory with an n component order parameter in d dimensions. A new extremum criterion is introduced that reduces the error bars compared to earlier Borel summations [1]. Furthermore, Borel resummed results are presented for the universal amplitude ratios (1−A+/A−)/α, Rξ+, and RξT. Our results are compared with experimental data for the lambda transition of 4He [2] and with numerical data for XY type lattice models [3,4].
[1] R. Guida, J. Zinn-Justin, J. Phys. A 31, 8103 (1998).
[2] J.A. Lipa et al., Phys. Rev. B 68, 174518 (2003).
[3] M. Campostrini et al., Phys. Rev. B 74, 14450 (2006).
[4] M. Hasenbusch, J. Stat. Mech. P08019 (2006).