Mon·Aug 6, 2007Monday·August 6, 2007

1. 01*

   Fisher's zeros of quasi-Gaussian densities of states

   A. Denbleyker🇺🇸 · D. Du🇺🇸 · Y. Meurice🇺🇸 · A. Velytsky🇺🇸

   We discuss apparent paradoxes regarding the location of the zeros of the partition function in the complex $\beta$ plane (Fisher's zeros) of a pure SU(2) lattice gauge theory in 4 dimensions. We propose a new criterion to draw the region of the complex $\beta$ plane where reweighting methods can be trusted when the density of states is almost but not exactly Gaussian. We propose new methods to infer the existence of zeros outside of this region. We demonstrate the reliability of these proposals with quasi Gaussian Monte Carlo distributions where the locations of the zeros can be calculated by independent numerical methods. The results are presented in such way that the methods can be applied for general lattice models. Applications to specific lattice models will be discussed in a separate publication.

   hep-latcond-mat.stat-mechhep-thPRD(2007)·12 citations
2. 02*

   Determination of light quark masses from the electromagnetic splitting of pseudoscalar meson masses computed with two flavors of domain wall fermions

   Thomas Blum🇺🇸 · Takumi Doi🇺🇸 · Masashi Hayakawa🇯🇵 · Taku Izubuchi🇺🇸 · Norikazu Yamada🇯🇵

   We determine the light quark masses from lattice QCD simulations incorporating the electromagnetic interaction of valence quarks. The meson masses are calculated on lattice QCD configurations generated by the RBC Collaboration for two flavors of dynamical domain wall fermions, which are combined with QED configurations generated via quenched non-compact lattice QED. The electromagnetic part of the pion mass splitting is found to be $m_{{\pi }^{+}}-m_{{\pi }^0}=4.12(21)$ MeV, where only the statistical error is quoted, and similarly for the kaon, 1.443(55) MeV. Our results for the light quark masses are $m_u^{\overline{\mathrm{MS}}}$(2 GeV)=$3.02(27)(19)$ MeV, $m_d^{\overline{\mathrm{MS}}}$(2 GeV)=$5.49(20)(34)$ MeV, and $m_s^{\overline{\mathrm{MS}}}$(2 GeV)=$119.5(56)(74)$ MeV, where the first error is statistical and the second systematic. By averaging over $\pm e$ to cancel $\mathcal{O}(e)$ noise exactly on each combined gauge field configuration, we are able to work at physical $\alpha =1/137$ and obtain very small statistical errors. In our calculation, several sources of systematic error remain, including finite volume, non-zero lattice spacing, chiral extrapolation, quenched QED, and quenched strange quark, which may be more significant than the errors quoted above.

   hep-lathep-phPRD(2007)·111 citations

* 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.