HEP Lattice·hep-lat
8 papers—7 primary·1 cross-listed·reconstructed*
The legality of the "rooting trick" in dynamical staggered fermion simulations is discussed, i.e. whether the theory with the Boltzmann weight yields the right continuum limit. Since the problem is unsolved, pieces of evidence in favor and against are collected and examined.
Ronald Babich (1)🇺🇸 · Federico Berruto (2)🇺🇸 · Nicolas Garron (3)🇩🇪 · Christian Hoelbling (4)🇩🇪 · Joseph Howard (1)🇺🇸 · Laurent Lellouch (5)🇫🇷 · Claudio Rebbi (1)🇺🇸 · Noam Shoresh (6) ((1) Boston University, (2) BNL, (3) DESY, (4) Wuppertal, (5) CPT Marseille, (6) Harvard University)🇺🇸
A simulation of quenched QCD with the overlap Dirac operator has been completed using 100 Wilson gauge configurations at beta = 6 on an 18^3 x 64 lattice and at beta = 5.85 on a 14^3 x 48 lattice, both in Landau gauge. We present results for light meson and baryon masses, meson final state "wave functions," and other observables, as well as some details on the numerical techniques that were used. Our results indicate that scaling violations, if any, are small. We also present an analysis of diquark correlations using the quark propagators generated in our simulation.
M. S. Cook🇺🇸 · H. R. Fiebig (the LHP Collaboration)🇺🇸
We present results of a decay width calculation for a hybrid exotic meson(h, JPC=1-+) in the decay channel h to pi+a1. This calculation uses quenched lattice QCD and Luescher's finite box method. Operators for the h and pi+a1 states are used in a correlation matrix which was expanded by varying the smearing and fuzzing levels at source and sink points. Scattering phase shifts for a discrete set of relative pi+a1 momenta are determined using eigenvalues of the correlation matrix and formulae derived by Luescher. The phase shift data is very sparse, but fits to a Breit-Wigner model are made, resulting in a decay width of about 80 MeV.
Ulf-G. Meißner (HISKP, Univ. Bonn and IKP, FZ Jülich)🇩🇪
I discuss the quark mass dependence of various baryon properties derived from chiral perturbation theory. Such representations can eventually be used as chiral extrapolation functions when lattice data at sufficiently small quark masses become available. The quark mass dependence is encoded in loop and contact term contributions, the latter given in terms of low-energy constants. I stress the importance of utilizing phenomenological input to constrain a certain class of low-energy constants and discuss the ensuing theoretical uncertainty for various baryon observables, like the nucleon and the baryon octet masses, the nucleon isovector anomalous magnetic moment and the axial-vector coupling of the nucleon. I stress the role of resonance decoupling and present first results for the delta mass based on an effective field theory in which the nucleon-delta mass splitting is counted as a small parameter. I also discuss briefly the pion mass dependence of the nuclear force as derived from chiral nuclear effective field theory.
Stefano Capitani🇦🇹 · Christof Gattringer🇦🇹 · C. B. Lang🇦🇹
We present results for Monte Carlo calculations of the electromagnetic vector and scalar form factors of the pion in a quenched simulation. We work at a lattice spacing of 0.15 fm and use two lattice volumes up to a spatial size of 2.4 fm. The pion form factors in the space-like region are determined for pion masses down to 340 MeV.
In this talk I summarise recent results on the infrared exponents of SU()-Yang-Mills theory. I discuss a self-consistent power law solution for the Dyson-Schwinger equations for general 1PI-Greens functions in the infrared. The corresponding running coupling has a fixed point at zero momentum, which turns out to be universal and gauge invariant within a class of transverse gauges. When calculated on a torus the infrared exponents of the ghost and gluon propagators differ from the corresponding continuum solutions. They agree, however, well with results from lattice calculations.
Joshua W. Elliott🇨🇦 · Guy D. Moore (McGill University)🇨🇦
We show how 3-dimensional, N=2 supersymmetric theories, including super QCD with matter fields, can be put on the lattice with existing techniques, in a way which will recover supersymmetry in the small lattice spacing limit. Residual supersymmetry breaking effects are suppressed in the small lattice spacing limit by at least one power of the lattice spacing a.
V.I. Zakharov · MPI-Munich (Germany)
We overview the issue of the power corrections to the parton model, mostly within the context of QCD sum rules. There are a few sources of the power corrections responsible for various qualitative effects. The basic idea that the power corrections are related to confining fields seems to be realized in case of corrections which are dual to high orders of perturbation theory. The evidence comes from lattice studies of the confinement which allowed to identify the confining field configurations as monopoles and vortices. We comment also on the role of the condensate of dimension two, .
* 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.