@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} }