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We present highlights of the spectrum of mesons and baryons calculated using NRQCD for heavy quarks and tadpole improved clover action for the light quarks.

High Energy Physics - Lattice · Physics 2015-06-25 Rajan Gupta

We show that it is possible to improve the chiral behaviour and the approach to the continuum limit of correlation functions in lattice QCD with Wilson fermions by taking arithmetic averages of correlators computed in theories regularized…

High Energy Physics - Lattice · Physics 2009-11-10 R. Frezzotti , G. C. Rossi

We report the final results of the ALPHA collaboration for some B-physics observables: $f_B$, $f_{B_s}$ and $m_b$. We employ CLS configurations with 2 flavors of $O(a)$ improved Wilson fermions in the sea and pion masses ranging down to 190…

High Energy Physics - Lattice · Physics 2013-09-05 F. Bernardoni , B. Blossier , J. Bulava , M. Della Morte , P. Fritzsch , N. Garron , A. Gerardin , J. Heitger , G. von Hippel , H. Simma , R. Sommer

By considering the local vector current between nucleon states and imposing charge conservation we determine, for $O(a)$ improved Wilson fermions, its renormalisation constant and quark mass improvement coefficient. The computation is…

High Energy Physics - Lattice · Physics 2008-11-26 T. Bakeyev , M. Gockeler , R. Horsley , D. Pleiter , P. E. L. Rakow , A. Schafer , G. Schierholz , H. Stuben

We briefly describe some of our recent results for the mass spectrum and matrix elements using $O(a)$ improved fermions for quenched QCD. Where possible a comparison is made between improved and Wilson fermions.

High Energy Physics - Lattice · Physics 2007-05-23 S. Capitani , M. Goeckeler , R. Horsley , B. Klaus , H. Oelrich , H. Perlt , D. Petters , D. Pleiter , P. Rakow , G. Schierholz , A. Schiller , P. Stephenson

We calculate spin averaged splittings in the bottomonium and charmonium systems using the clover action. We compare static and kinetic masses of heavy-heavy and heavy-light mesons and discuss the consistency of the results.

High Energy Physics - Lattice · Physics 2010-01-18 Sara Collins , Robert G. Edwards , Urs M. Heller , John Sloan

I report on cost estimates and algorithmic performance in simulations using 2 flavours of non-perturbatively O(a) improved Wilson quarks together with the Wilson plaquette action.

High Energy Physics - Lattice · Physics 2009-11-07 H. Wittig

We present an adaptive multigrid Dirac solver developed for Wilson clover fermions which offers order-of-magnitude reductions in solution time compared to conventional Krylov solvers. The solver incorporates even-odd preconditioning and…

High Energy Physics - Lattice · Physics 2011-05-25 J. C. Osborn , R. Babich , J. Brannick , R. C. Brower , M. A. Clark , S. D. Cohen , C. Rebbi

We describe the extension of the improvement program for bilinear operators composed of Wilson fermions to non-degenerate dynamical quarks. We consider two, three and four flavors, and both flavor non-singlet and singlet operators. We find…

High Energy Physics - Lattice · Physics 2009-11-11 Tanmoy Bhattacharya , Rajan Gupta , Weonjong Lee , Stephen R. Sharpe , Jackson M. S. Wu

We present an update of our study of the phase diagram of two-flavour QCD at zero baryon density with dynamical $O(a)$ improved Wilson quarks. All simulations are done on lattices with a temporal extent of $N_t=16$ and spatial extent…

High Energy Physics - Lattice · Physics 2013-11-01 Bastian B. Brandt , Anthony Francis , Harvey B. Meyer , Owe Philipsen , Hartmut Wittig

The renormalization factor and O(a) improvement coefficient of four-quark operators are calculated perturbatively for the improved Wilson fermion action with clover term and the Iwasaki gauge action. With an application to the $K\to\pi\pi$…

High Energy Physics - Lattice · Physics 2015-06-04 Yusuke Taniguchi

QCD is investigated at finite temperature using Wilson fermions in the fixed scale approach. A 2+1 flavor stout and clover improved action is used at four lattice spacings allowing for control over discretization errors. The light quark…

We consider a Wilson-Dirac operator with improved chiral properties. We show that, for arbitrarily rough gauge fields, it satisfies the index theorem if we identify the zero modes with the small real eigenvalues of the fermion operator and…

High Energy Physics - Lattice · Physics 2009-10-31 P. Hernandez

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

Baryonic correlation functions provide an ideal tool to study parity doubling and chiral symmetry using lattice simulations. We present a study using $2+1$ flavors of anisotropic Wilson clover fermions on the FASTSUM ensembles and find…

High Energy Physics - Lattice · Physics 2016-07-19 Gert Aarts , Chris Allton , Davide De Boni , Simon Hands , Benjamin Jäger , Chrisanthi Praki , Jon-Ivar Skullerud

After describing the Schr\"odinger functional for standard and improved gluon and quark actions we present results for the non-perturbative clover coefficients of the SW quark action coupled to the Wilson plaquette action for $\beta \geq…

High Energy Physics - Lattice · Physics 2009-10-30 R. G. Edwards , U. M. Heller , T. R. Klassen

Overlap fermions are particularly well suited to study the finite temperature dynamics of the chiral symmetry restoration transition of QCD, which might be just an analytic crossover. Using gauge field configurations on a 24^3x10 lattice…

High Energy Physics - Lattice · Physics 2008-11-26 V. Weinberg , E. -M. Ilgenfritz , K. Koller , Y. Koma , Y. Nakamura , G. Schierholz , T. Streuer

We present a calculation of pion electromagnetic and scalar form factors in two-flavor QCD with the non-perturbatively O(a)-improved Wilson fermion. Chiral extrapolation of the corresponding charge radius is discussed based on the chiral…

I describe a recent calculation (by me, Hoffmann, Liu, and Schaefer) of the chiral condensate in one-flavor QCD using numerical simulations with overlap fermions. The condensate is extracted by fitting the distribution of low lying…

High Energy Physics - Lattice · Physics 2008-11-26 Thomas DeGrand

We present results on the light hadron spectrum and quark mass in two-flavor QCD calculated with small sea quark masses down to $m_{PS}/m_{V}=0.35$. The configurations are generated using the RG improved gauge and tadpole-improved clover…