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Normalized hypercubic smearing improves the behavior of dynamical Wilson-clover fermions, but has the unwanted side effect that it can occasionally produce spikes in the fermion force. These spikes originate in the chain rule connecting the…

High Energy Physics - Lattice · Physics 2014-09-10 Thomas DeGrand , Yigal Shamir , Benjamin Svetitsky

The masses and dispersions of light hadrons are calculated in lattice QCD using an order a^2 tadpole-improved gluon action and the Dchi34 action, an order a^2 tadpole-improved next-nearest-neighbor fermion action originally proposed by…

High Energy Physics - Lattice · Physics 2007-05-23 Derek B. Leinweber , Frank X. Lee

We discuss simulations with different lattice Dirac operators for sea and valence quarks. A goal of such a "mixed" action approach is to probe deeper the chiral regime of QCD by enabling simulations with light valence quarks. This is…

High Energy Physics - Lattice · Physics 2014-11-17 O. Baer , G. Rupak , N. Shoresh

Different versions of improved staggered fermions can be used as valence quarks to reduce discretization effects in lattice QCD calculations while increasing statistics on existing staggered gauge ensembles. Such mixed-action simulations…

High Energy Physics - Lattice · Physics 2013-11-26 Jon A. Bailey , Jongjeong Kim , Weonjong Lee , Hyung-Jin Kim , Boram Yoon

We calculate in three-flavor lattice QCD the short-distance hadronic matrix elements of all five $\Delta C=2$ four-fermion operators that contribute to neutral $D$-meson mixing both in and beyond the Standard Model. We use the MILC…

We present results for pseudoscalar decay constants of heavy-light mesons using both quenched and N_f = 2 dynamical fermion configurations. A variety of fermion actions is investigated : Wilson, nonperturbative clover, and fat-link clover.…

High Energy Physics - Lattice · Physics 2008-11-26 C. Bernard , S. Datta , C. DeTar , S. Gottlieb , U. M. Heller , J. Hetrick , C. Mcneile , K. Orginos , R. Sugar , D. Toussaint

Updates on results for the electric, magnetic and axial vector form factors are presented. The data analyzed cover high statistics measurements on 11 ensembles generated with 2+1+1 flavors of HISQ fermions by the MILC collaboration. The…

High Energy Physics - Lattice · Physics 2019-02-01 Yong-Chull Jang , Tanmoy Bhattacharya , Rajan Gupta , Huey-Wen Lin , Boram Yoon

A chiral fermion action allows one to do very clean studies of chiral symmetry breaking in QCD. I will briefly describe how to compute with the overlap action (relatively) cheaply, and then turn to physics: Low modes of the Dirac operator…

High Energy Physics - Lattice · Physics 2007-05-23 Thomas DeGrand

Mixed action lattice QCD with Borici-Creutz valence quarks on staggered sea is investigated. The counter terms in Borici-Creutz action are fixed nonperturbatively to restore the broken parity and time symmetries. On symmetry restoration,…

High Energy Physics - Lattice · Physics 2017-10-25 S. Basak , D. Chakrabarti , J. Goswami

We study exceptional modes of both the Wilson and the clover action in order to understand why quenched clover spectroscopy suffers so severely from exceptional configurations. We show that, in contrast to the case of the Wilson action, a…

High Energy Physics - Lattice · Physics 2015-06-25 T. DeGrand , A. Hasenfratz , T. G. Kovacs

We consider two-component fermions with short-range interactions and large scattering length. This system has universal properties that are realized in several different fields of physics. In the limit of large fermion-fermion scattering…

Nuclear Theory · Physics 2017-03-15 Serdar Elhatisari , Kris Katterjohn , Dean Lee , Ulf-G. Meißner , Gautam Rupak

I demonstrate that the chiral properties of Domain Wall Fermions (DWF) in the large to intermediate lattice spacing regime of QCD, 1 to 2 GeV, are significantly improved by adding to the action two standard Wilson fermions with…

High Energy Physics - Lattice · Physics 2008-11-26 Pavlos M. Vranas

Chiral symmerty is presumed to be a crucial component in the strong interaction and QCD, but its role in spectroscopy, especially for baryons, has not been fully explored. Compounding this, chiral fermions are uncommon in lattice…

High Energy Physics - Lattice · Physics 2018-12-07 Jacob Fallica , Keh-Fei Liu , Jian Liang , Gen Wang , Yi-Bo Yang

We describe a way to optimize the chiral behavior of Wilson-type lattice fermion actions by studying the low energy real eigenmodes of the Dirac operator. We find a candidate action, the clover action with fat links with a tuned clover…

High Energy Physics - Lattice · Physics 2009-10-31 Thomas DeGrand , Anna Hasenfratz , Tamas G. Kovacs

We present physical results for a variety of light hadronic quantities obtained via a combined analysis of three 2+1 flavour domain wall fermion ensemble sets. For two of our ensemble sets we used the Iwasaki gauge action with beta=2.13…

The strange quark mass has been computed using a lattice action which possesses continuum--like chiral symmetry to good precision, namely the domain wall fermion action. This talk surveys this action and the recent calculation of m_s by the…

High Energy Physics - Phenomenology · Physics 2009-10-31 Matthew Wingate

We review recent results for the chiral behavior of meson masses and decay constants and the determination of the light quark masses by the RBC and UKQCD collaborations. We find that one-loop SU(2) chiral perturbation theory represents the…

High Energy Physics - Lattice · Physics 2010-01-21 Enno E. Scholz

We present a quenched lattice QCD calculation of the first few moments of the polarized and un-polarized structure functions of the nucleon. Our calculations are done using domain wall fermions and the DBW2 gauge action with inverse lattice…

High Energy Physics - Lattice · Physics 2011-08-11 Kostas Orginos , Thomas Blum , Shigemi Ohta

We present our result for the $K\to\pi\pi$ decay amplitudes for both the $\Delta I=1/2$ and $3/2$ processes with the improved Wilson fermion action. Expanding on the earlier works by Bernard {\it et al.} and by Donini {\it et al.}, we show…

High Energy Physics - Lattice · Physics 2015-10-14 N. Ishizuka , K. -I. Ishikawa , A. Ukawa , T. Yoshié

We report on studies of the chiral properties of dynamical domain wall fermions combined with the DBW2 gauge action for different gauge couplings and fermion masses. For quenched theories, the DBW2 action gives a residual chiral symmetry…

High Energy Physics - Lattice · Physics 2010-11-15 L. Levkova , R. Mawhinney