@misc{IlgenfritzKerlerMuellerPreusskeretal., author = {Ilgenfritz, Ernst-Michael and Kerler, Werner and M{\"u}ller-Preussker, Michael and St{\"u}ben, Hinnerk}, title = {Parallel tempering in full QCD with Wilson fermions}, url = {http://nbn-resolving.de/urn:nbn:de:0297-zib-6593}, number = {01-33}, abstract = {We study the performance of QCD simulations with dynamical Wilson fermions by combining the Hybrid Monte Carlo algorithm with parallel tempering on \$10^4\$ and \$12^4\$ lattices. In order to compare tempered with standard simulations, covariance matrices between sub-ensembles have to be formulated and evaluated using the general properties of autocorrelations of the parallel tempering algorithm. We find that rendering the hopping parameter \$\kappa\$ dynamical does not lead to an essential improvement. We point out possible reasons for this observation and discuss more suitable ways of applying parallel tempering to QCD.}, language = {en} } @misc{IlgenfritzKerlerMuellerPreusskeretal., author = {Ilgenfritz, Ernst-Michael and Kerler, Werner and M{\"u}ller-Preussker, Michael and St{\"u}ben, Hinnerk}, title = {Parallel tempering and decorrelation of topological charge in full QCD}, url = {http://nbn-resolving.de/urn:nbn:de:0297-zib-5930}, number = {00-25}, abstract = {The improvement of simulations of QCD with dynamical Wilson fermions by combining the Hybrid Monte Carlo algorithm with parallel tempering is studied on \$10^4\$ and \$12^4\$ lattices. As an indicator for decorrelation the topological charge is used.}, language = {en} } @misc{IlgenfritzKerlerMuellerPreusskeretal., author = {Ilgenfritz, Ernst-Michael and Kerler, Werner and M{\"u}ller-Preussker, Michael and Sternbeck, Andr{\´e} and St{\"u}ben, Hinnerk}, title = {A numerical reinvestigation of the Aoki phase with \$N_f=2\$ Wilson fermions at zero temperature}, url = {http://nbn-resolving.de/urn:nbn:de:0297-zib-7492}, number = {03-27}, abstract = {We report on a numerical reinvestigation of the Aoki phase in lattice QCD with two flavors of Wilson fermions where the parity-flavor symmetry is spontaneously broken. For this purpose the Hybrid Monte Carlo algorithm was used and an explicit symmetry-breaking source term \$h\bar{\psi} i \gamma_{5} \tau^{3}\psi\$ was added to the Wilson fermion action. The order parameter \$\langle\bar{\psi}i\gamma_{5}\tau^{3}\psi\rangle\$ was studied at several values of \$(\beta,\kappa,h)\$ on lattices of sizes \$4^4\$ to \$12^4\$. Our largest lattices can be considered as infintely large allowing to extrapolate to \$h=0\$. The existence of a parity-flavor-breaking phase can be confirmed at \$\beta=4.0\$ and \$\beta=4.3\$ while we find no sign of parity-flavor-breaking at \$\beta=4.6\$ and \$\beta=5.0\$.}, language = {en} } @misc{IlgenfritzKerlerMuellerPreusskeretal., author = {Ilgenfritz, Ernst-Michael and Kerler, Werner and M{\"u}ller-Preussker, Michael and Sternbeck, Andre and St{\"u}ben, Hinnerk}, title = {Probing the Aoki phase with N_f=2 Wilson fermions at finite temperature}, url = {http://nbn-resolving.de/urn:nbn:de:0297-zib-8812}, number = {05-48}, abstract = {In this letter we report on a numerical investigation of the Aoki phase in the case of finite temperature which continues our former study at zero temperature. We have performed simulations with Wilson fermions at \$\beta=4.6\$ using lattices with temporal extension \$N_{\tau}=4\$. In contrast to the zero temperature case, the existence of an Aoki phase can be confirmed for a small range in \$\kappa\$ at \$\beta=4.6\$, however, shifted slightly to lower \$\kappa\$. Despite fine-tuning \$\kappa\$ we could not separate the thermal transition line from the Aoki phase.}, language = {en} } @misc{IlgenfritzKerlerStueben, author = {Ilgenfritz, Ernst-Michael and Kerler, Werner and St{\"u}ben, Hinnerk}, title = {Decorrelation of the topological charge in tempered Hybrid Monte Carlo simulations of QCD}, url = {http://nbn-resolving.de/urn:nbn:de:0297-zib-4168}, number = {SC-99-28}, abstract = {We study the improvement of simulations of QCD with dynamical Wilson fermions by combining the Hybrid Monte Carlo algorithm with parallel tempering. As an indicator for decorrelation we use the topological charge.}, language = {en} }