Thu·Sep 20, 2001Thursday·September 20, 2001

1. 01*

   Specific heat and energy for the three-dimensional O(2) model

   S. Holtmann🇩🇪 · J. Engels🇩🇪 · T. Schulze (University Bielefeld, Germany)🇩🇪

   We investigate the three-dimensional O(2) model on lattices of size 8^3 to 160^3 close to the critical point at zero magnetic field. We confirm explicitly the value of the critical coupling J_c found by Ballesteros et al. and estimate there the universal values of g_r and xi/L. At the critical point we study the finite size dependencies of the energy density epsilon and the specific heat C. We find that the nonsingular part of the specific heat C_{ns} is linearly dependent on 1/alpha. From the critical behaviour of the specific heat for T not T_c on the largest lattices we determine the universal amplitude ratio A+/A-. The alpha- dependence of this ratio is close to the phenomenological relation A+/A- = 1-4alpha.

   hep-latcond-mat.stat-mechNucl.Phys.B Proc.Suppl.(2002)·4 citations
2. 02*

   Spin splittings among charmed hadrons

   Randy Lewis🇨🇦 · Nilmani Mathur🇨🇦 · R. M. Woloshyn🇨🇦

   The mass differences between spin-1/2 and spin-3/2 baryons are compared to the mass differences between spin-0 and spin-1 mesons. Results of simulations for charmed hadrons in the quenched approximation from a tadpole-improved anisotropic action are discussed in the context of other lattice calculations, quark model predictions, heavy quark symmetry predictions and experimental data.

   hep-latNucl.Phys.B Proc.Suppl.(2002)·4 citations
3. 03*

   Quantum Fields far from Equilibrium and Thermalization

   J. Berges🇩🇪

   I review the use of the 2PI effective action in nonequilibrium quantum field theory. The approach enables one to find approximation schemes which circumvent long-standing problems of non-thermal or secular (unbounded) late-time evolutions encountered in standard loop or 1/N expansions of the 1PI effective action. It is shown that late-time thermalization can be described from a numerical solution of the three-loop 2PI effective action for a scalar ${\varphi }^4$--theory in 1+1 dimensions (with Jurgen Cox, hep-ph/0006160). Quantitative results far from equilibrium beyond the weak coupling expansion can be obtained from the 1/N expansion of the 2PI effective action at next-to-leading order (NLO), calculated for a scalar O(N) symmetric quantum field theory (hep-ph/0105311). Extending recent calculations in classical field theory by Aarts et al. (hep-ph/0007357) and by Blagoev et al. (hep-ph/0106195) to $N>1$ we show that the NLO approximation converges to exact (MC) results already for moderate values of $N$ (with Gert Aarts, hep-ph/0107129). I comment on characteristic time scales in scalar quantum field theory and the applicability of classical field theory for sufficiently high initial occupation numbers.

   ↳ hep-phhep-lathep-thnucl-th1 citation

* Reconstructed cohort: no mailing for this day survives in the archive. Papers are grouped by their submission times and arXiv's announcement cut-off, assuming announcement without delay; positions follow identifier order. Validated at ~91% exact-day agreement against the archived era.