2,448 research outputs found
New fermion discretizations and their applications
We review the recent progress in new lattice fermion formulations. We focus
on the following three types which have possibility of improving lattice
simulations. (1) Flavored-mass fermions are a generalization of Wilson fermions
with species-splitting mass terms. In particular, staggered-Wilson fermions
initiated by Adams have possibilities of reducing numerical costs in overlap
fermions and the influence of taste-breaking in staggered fermions. (2)
Central-branch Wilson fermions, in which additive mass renormalization is
forbidden by extra axial symmetry, could enable us to perform Wilson-fermion
lattice QCD without fine-tuning. (3) Minimally doubled fermions, which reduce
the number of species by species-dependent chemical potential terms, realizes a
ultra-local chiral fermion at the price of hypercubic symmetry. These setups
reveal unknown aspects of lattice fermions, and we obtain a deeper
understanding of lattice field theory.Comment: 15 pages, 9 figures, plenary talk presented at the 30th International
Symposium on Lattice Field Theory - Lattice 2012, June 24-29, 2012 Cairns,
Australi
Characters of Lattice Fermions Based on the Hyperdiamond Lattice
We study minimal-doubling fermion actions on hyperdiamond and deformed
hyperdiamond lattices, with emphasis on the real-space construction of them and
Lorentz covariance of excitations from fermion poles. We propose the improved
spatial construction of Creutz fermion action on a deformed hyperdiamond
lattice, and discuss conditions for a hyperdiamond-lattice action to produce
Lorentz-covariant excitations from poles of fermion propagators. It is pointed
out that the non-nearest-site hoppings are essential for the correct
excitations. We propose a class of minimal-doubling actions defined on a
deformed hypercubic lattice as a generalization of Creutz-type actions. In
addition we introduce a two-parameter class of Wilczek-type minimal-doubling
actions.Comment: 22 pages, 3 figures. v2:Discussion clarified and extended, the order
of sections changed. v3:final version accepted for publicatio
Lattice Fermions Based on Higher-Dimensional Hyperdiamond Lattices
In this paper we generalize to higher dimensions several types of fermion
actions on the hyperdiamond lattice including a two-parameter class of
minimal-doubling fermions "Creutz fermion" and a simple fermion with sufficient
discrete symmetry "BBTW fermion". Then it is shown that they possess some
properties in common with the four-dimensional case: BBTW fermions in higher
even dimensions inevitably yield unphysical degrees of freedom. Creutz fermions
are defined on the distorted lattices, and they lose the high discrete symmetry
of the original lattices. We also find properties specific to the
higher-dimensional cases. The parameter range for Creutz action to yield
minimal-doubling and physical fermions becomes narrower with the dimension
getting higher, thus it becomes more and more difficult to realize
minimal-doubling. In addition, we generalize the subspecies of Creutz and BBTW
actions including a new class of minimal-doubling actions "Appended Creutz
action".Comment: 18 pages, 2 figures. To appear in Prog. Theo. Phy
- …