TY - GEN A1 - Ilgenfritz, Ernst-Michael A1 - Kerler, Werner A1 - Müller-Preussker, Michael A1 - Sternbeck, André A1 - Stüben, Hinnerk T1 - A numerical reinvestigation of the Aoki phase with $N_f=2$ Wilson fermions at zero temperature N2 - 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 $\beta=5.0$. T3 - ZIB-Report - 03-27 KW - Wilson fermions KW - phase diagram KW - parity-flavor symmetry KW - Aoki phase Y1 - 2003 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-7492 ER - TY - GEN A1 - Ilgenfritz, Ernst-Michael A1 - Kerler, Werner A1 - Müller-Preussker, Michael A1 - Sternbeck, Andre A1 - Stüben, Hinnerk T1 - Probing the Aoki phase with N_f=2 Wilson fermions at finite temperature N2 - 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. T3 - ZIB-Report - 05-48 KW - Wilson fermions KW - phase diagram KW - parity-flavor symmetry KW - Aoki phase KW - finite temperature Y1 - 2005 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-8812 ER -