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We study QCD thermodynamics using two flavors of dynamical overlap fermions with quark masses corresponding to a pion mass of 350 MeV. We determine several observables on N_t=6 and 8 lattices. All our runs are performed with fixed global…

High Energy Physics - Lattice · Physics 2012-08-03 S. Borsanyi , Y. Delgado , S. Durr , Z. Fodor , S. D. Katz , S. Krieg , T. Lippert , D. Nogradi , K. K. Szabo

We present relaxation and preconditioning techniques which accelerate the inversion of the overlap operator by a factor of four on small lattices, with larger gains as the lattice size increases. These improvements can be used in both…

High Energy Physics - Lattice · Physics 2009-11-10 S. Krieg , N. Cundy , J. van den Eshof , A. Frommer , Th. Lippert , K. Schäfer

We compute light and strange quark masses for quenched overlap fermions at two values of the gauge coupling. The renormalisation is done non-perturbatively. We test the predictions of quenched chiral perturbation theory for the quark mass…

High Energy Physics - Lattice · Physics 2007-05-23 Martin Gürtler , Thomas Streuer , Gerrit Schierholz , David Galletly , Roger Horsley , Paul Rakow

I present first results from an in-progress calculation of B_K in quenched approximation using overlap fermions. My particular implementation of the overlap uses a kernel with nearest and next-nearest neighbor interactions and HYP-blocked…

High Energy Physics - Lattice · Physics 2015-06-25 Thomas DeGrand

We present first results from a simulation of quenched overlap fermions with improved gauge field action. Among the quantities we study are the spectral properties of the overlap operator, the chiral condensate and topological charge, quark…

High Energy Physics - Lattice · Physics 2008-11-26 D. Galletly , M. Gürtler , R. Horsley , B. Joo , A. D. Kennedy , H. Perlt , B. J. Pendleton , P. E. L. Rakow , G. Schierholz , A. Schiller , T. Streuer

We report on our exploratory study for the evaluation of the parton distribution functions from lattice QCD, based on a new method proposed in Ref.~arXiv:1305.1539. Using the example of the nucleon, we compare two different methods to…

We perform dynamical QCD simulations with $n_f=2$ overlap fermions by hybrid Monte-Carlo method on $6^4$ to $8^3\times 16$ lattices. We study the problem of topological sector changing. A new method is proposed which works without…

High Energy Physics - Lattice · Physics 2009-11-11 G. I. Egri , Z. Fodor , S. D. Katz , K. K. Szabo

We present results from a simulation of quenched overlap fermions with L\"uscher-Weisz gauge field action on lattices up to $24^3 48$ and for pion masses down to $\approx 250$ MeV. Among the quantities we study are the pion, rho and nucleon…

High Energy Physics - Lattice · Physics 2008-11-26 D. Galletly , M. Gürtler , R. Horsley , H. Perlt , P. E. L. Rakow , G. Schierholz , A. Schiller , T. Streuer

The Fixed Point Dirac Operator and Chirally Improved Fermions both use large numbers of gauge paths and the full Dirac structure to approximate a solution of the Ginsparg-Wilson equation. After a brief review of the two approaches we…

High Energy Physics - Lattice · Physics 2009-11-07 Christof Gattringer

Computing quark propagators with overlap fermions requires the solution of a shifted unitary linear system. Jagels and Reichel have shown that for such systems it is possible to construct a minimal residual algorithm by short recurrences.…

High Energy Physics - Lattice · Physics 2007-05-23 Artan Borici , Alban Allkoci

We present a calculation of the up, down, strange and charm quark masses performed within the lattice QCD framework. We use the twisted mass fermion action and carry out simulations that include in the sea two light mass-degenerate quarks,…

The overlap formula for the chiral determinant is presented and the realization of gauge anomalies and gauge field toplogy in this context is discussed. The ability of the overlap formalism to deal with supersymmetric theories and…

High Energy Physics - Lattice · Physics 2009-09-25 Rajamani Narayanan

A new deterministic, numerical method to solve fermion field theories is presented. This approach is based on finding solutions $Z[J]$ to the lattice functional equations for field theories in the presence of an external source $J$. Using…

High Energy Physics - Theory · Physics 2009-10-28 John W. Lawson , G. S. Guralnik

Using the second moment of the pion distribution amplitude as an example, we investigate whether lattice calculations of matrix elements of local operators involving covariant derivatives may benefit from the recently proposed momentum…

High Energy Physics - Lattice · Physics 2018-02-01 RQCD Collaboration , G. S. Bali , V. M. Braun , M. Göckeler , M. Gruber , F. Hutzler , P. Korcyl , B. Lang , A. Schäfer

We review the spectral flow techniques for computing the index of the overlap Dirac operator including results relevant for SUSY Yang-Mills theories. We describe properties of the overlap Dirac operator, and methods to implement it…

High Energy Physics - Lattice · Physics 2008-11-26 R. G. Edwards , U. M. Heller , R. Narayanan

The well-known physical equivalence drawn from hole theory is applied in this article. The author suggests to replace, in the part of Feynman diagram which cannot be fixed by experiments, each fermion field operator, and hence fermion…

High Energy Physics - Theory · Physics 2011-04-20 Ji Sun

We calculate the scalar and tensor charges of the nucleon in 2+1-flavor lattice QCD, for which the systematics of the renormalization of the disconnected diagram is well controlled. Numerical simulations are performed at a single lattice…

High Energy Physics - Lattice · Physics 2018-09-27 Nodoka Yamanaka , Shoji Hashimoto , Takashi Kaneko , Hiroshi Ohki

We present an update of the light meson spectrum with $N_f$=2+1 overlap fermions on a $16^3\times 48$ lattice at five different up and down quark masses and two strange quark masses. Based on our experience with the previous simulation with…

High Energy Physics - Lattice · Physics 2012-08-27 JLQCD , TWQCD Collaborations , : , J. Noaki , S. Aoki , T. W. Chiu , H. Fukaya , S. Hashimoto , T. H. Hsieh , T. Kaneko , H. Matsufuru , T. Onogi , E. Shintani , N. Yamada

We report on simulation results with overlap hypercube fermions (overlap HF) - a type of exactly chiral lattice fermions - and their link to chiral perturbation theory. We first sketch the construction of the overlap HF and discuss its high…

High Energy Physics - Lattice · Physics 2011-04-11 W. Bietenholz , S. Shcheredin

I present one-loop perturbative calculations of matching coefficients between matrix elements in continuum regulated QCD and lattice QCD with overlap fermions, with emphasis a recently-proposed variant discretization of the overlap. These…

High Energy Physics - Lattice · Physics 2016-09-01 Thomas DeGrand
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