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A More improved lattice action for heavy quarks

Description: We extend the Fermilab formalism for heavy quarks to develop a more improved action. We give results of matching calculations of the improvement couplings at tree level. Finally, we estimate the discretization errors associated with the new action.
Date: March 17, 2004
Creator: al., M. B. Oktay et
Partner: UNT Libraries Government Documents Department

Taste changing in staggered quarks

Description: The authors present results from a systematic perturbative investigation of taste-changing in improved staggered quarks. They show one-loop taste-changing interactions can be removed perturbatively by an effective four-quark term and calculate the necessary coefficients.
Date: January 5, 2004
Creator: al., Quentin Mason et
Partner: UNT Libraries Government Documents Department

Nucleon form factors from high statistics mixed-action calculations with 2+1 flavors

Description: We present new high-statistics results for nucleon form factors at pion masses of approximately 290, 350, 500, and 600 MeV using a mixed action of domain wall valence quarks on an improved staggered sea. We perform chiral fits to both vector and axial form factors and compare our results to experiment.
Date: December 1, 2009
Creator: Schroers, Wolfram; Edwards, Robert G; Engelhardt, Michael; Fleming, George Taminga; Hagler, Philipp; Lin, Huey-Wen et al.
Partner: UNT Libraries Government Documents Department

An improved method for extracting matrix elements from lattice three-point functions

Description: The extraction of matrix elements from baryon three-point functions is complicated by the fact that the signal-to-noise drops rapidly as a function of time. Using a previously discussed method to improve the signal-to-noise for lattice two-point functions, we use this technique to do so for lattice three-point functions, using electromagnetic form factors for the nucleon and Delta as an example.
Date: December 1, 2011
Creator: C. Aubin, K. Orginos
Partner: UNT Libraries Government Documents Department

QUARKONIUM CORRELATORS AT FINITE TEMPERATURE AND POTENTIAL MODELS.

Description: We discuss the calculations of quarkonium spectral functions in potential models and their implications for the interpretation of the lattice data on quarkonium correlators. In particular, we find that melting of different quarkonium states does not lead to significant change in the Euclidean time correlators. The large change of the quarkonium correlators above deconfinement observed in the scalar and axial-vector channels appears to be due to the zero mode contribution.
Date: July 30, 2007
Creator: MOCSY,A. & PETRECZKY, P.
Partner: UNT Libraries Government Documents Department

WHY ROOTING FAILS.

Description: I explore the origins of the unphysical predictions from rooted staggered fermion algorithms. Before rooting, the exact chiral symmetry of staggered fermions is a flavored symmetry among the four 'tastes.' The rooting procedure averages over tastes of different chiralities. This averaging forbids the appearance of the correct 't Hooft vertex for the target theory.
Date: July 30, 2007
Creator: Creutz, M.
Partner: UNT Libraries Government Documents Department

B ---> D* l nu with 2+1 flavors

Description: We present a calculation of the form factor for B {yields} D*l{nu} using a 2+1 improved staggered action for the light quarks (on the MILC configurations), and the Fermilab action for the heavy quarks. The form factor is computed at zero recoil using a new double ratio method which yields the form factor more directly than previous approaches.
Date: October 1, 2007
Creator: Laiho, Jack & /Fermilab /Washington U., St. Louis
Partner: UNT Libraries Government Documents Department

Lambda-bar, lambda(1) and m(b) in three-flavor (lattice) QCD

Description: The heavy-quark expansion for inclusive semi-leptonic B decays introduces {Lambda} and {lambda}1 , which are matrix elements in heavy-quark effective field theory. We review how they can be obtained from an analysis of the heavy quark mass dependence of heavy-light meson masses in lattice QCD. We present preliminary results for the bottom quark mass, mb, using {Lambda} and {lambda}1 for the Bs meson from a 2+1 sea-flavor unquenched calculation.
Date: October 1, 2006
Creator: Freeland, Elizabeth D.; Chicago, /Art Inst. of; Kronfeld, Andreas S.; Simone, James N.; Van de Water, Ruth S. & /Fermilab
Partner: UNT Libraries Government Documents Department

Update on onium masses with three flavors of dynamical quarks

Description: We update results presented at Lattice 2005 on charmonium masses. New ensembles of gauge configurations with 2+1 flavors of improved staggered quarks have been analyzed. Statistics have been increased for other ensembles. New results are also available for P-wave mesons and for bottomonium on selected ensembles.
Date: January 1, 2006
Creator: Gottlieb, Steven A.; Levkova, L.; U., /Indiana; Di Pierro, Massimo; U., /DePaul; El-Khadra, Aida Xenia et al.
Partner: UNT Libraries Government Documents Department

A lattice formulation of chiral gauge theories

Description: We present a method for implementing gauge theories of chiral fermions on the lattice. Discussed topics include: the lattice as a UV regulator, a chiral QED model, modification of the fermion determinant, large gauge-field momenta, and a non-perturbative problem.
Date: August 1, 1996
Creator: Bodwin, G.T.
Partner: UNT Libraries Government Documents Department

Static hybrid quarkonium potential with improved staggered quarks

Description: The authors are studying the effects of light dynamical quarks on the excitation energies of a flux tube between a static quark and antiquark. They report preliminary results of an analysis of the ground state potential and the {Sigma}{prime}{sub g}{sup +} and II{sub u} potentials. They have measured these potentials on closely matched ensembles of gauge configurations, generated in the quenched approximation and with 2+1 flavors of Asqtad improved staggered quarks.
Date: January 6, 2004
Creator: al., C. Bernard et
Partner: UNT Libraries Government Documents Department

The second moment of the pion light cone wave function

Description: We present a preliminary result for second moment of the light cone wave function of the pion. This parameter is the subject of a discrepancy between theoretical predictions (coming from lattice and sum rules) and a recent experimental result (that remarkably agrees with purely perturbative predictions). In this work we exploit lattice hypercubic symmetries to remove power divergences and, moreover, implement a full 1-loop matching for all the contributing operators.
Date: September 25, 2003
Creator: Debbio, Luigi del; Pierro, Massimo di & Dougall, Alex
Partner: UNT Libraries Government Documents Department

A relativistic O (a{sup 2}) improved action for heavy quarks

Description: The authors extend the Fermilab formalism for heavy quarks to develop an {Omicron}(a{sup 2}) improved relativistic action. They discuss their construction of the action, including the identification of redundant operators and the calculation of the improvement coefficients.
Date: January 5, 2004
Creator: al., M. B. Oktay et
Partner: UNT Libraries Government Documents Department

Recent results using all point quark propagators

Description: Pseudofermion methods for extracting all-point quark propagators are reviewed, with special emphasis on techniques for reducing or eliminating autocorrelations induced by low eigenmodes of the quark Dirac operator. Recent applications, including high statistics evaluations of hadronic current correlators and the pion form factor, are also described.
Date: January 6, 2004
Creator: Duncan, A. & Yoo, E. Eichten and J.
Partner: UNT Libraries Government Documents Department

QCD with chiral 4-fermion interactions ({chi}QCD)

Description: Lattice QCD with staggered quarks is augmented by the addition of a chiral 4-fermion interaction. The Dirac operator is now non-singular at m{sub q}=0, decreasing the computing requirements for light quark simulations by at least an order of magnitude. We present preliminary results from simulations at finite and zero temperatures for m{sub q}=0, with and without gauge fields. Chiral QCD enables simulations at physical u and d quark masses with at least an order of magnitude saving in CPU time. It also enables simulations with zero quark masses which is important for determining the equation of state. A renormalization group analysis will be needed to continue to the continuum limit. 7 refs., 2 figs.
Date: October 1, 1996
Creator: Kogut, J.B. & Sinclair, D.K.
Partner: UNT Libraries Government Documents Department

Bbar {right arrow} {pi}l {nu bar}}at three lattice spacings

Description: The increasing accuracy of experimental results for the exclusive, semileptonic decay {anti B}{yields}{pi}l{anti {nu}} requires a similarly acucrate calculation of the hadronic matrix elements, to determine {vert_bar}V{sub ub}{vert_bar}. We present preliminary results for the form factors of the B to light meson decay mode. Using results from three lattices in the range 5.7{<=}{beta}{<=}6.1 we study the dependence on the lattice spacing.
Date: November 1, 1998
Creator: S. Ryan, A. El-Khadra, S. Hashimoto, A. Kronfeld, P. Mackenzie, and J. Simone
Partner: UNT Libraries Government Documents Department

Physics of the 1 Teraflop RIKEN-BNL-Columbia QCD project. Proceedings of RIKEN BNL Research Center workshop: Volume 13

Description: A workshop was held at the RIKEN-BNL Research Center on October 16, 1998, as part of the first anniversary celebration for the center. This meeting brought together the physicists from RIKEN-BNL, BNL and Columbia who are using the QCDSP (Quantum Chromodynamics on Digital Signal Processors) computer at the RIKEN-BNL Research Center for studies of QCD. Many of the talks in the workshop were devoted to domain wall fermions, a discretization of the continuum description of fermions which preserves the global symmetries of the continuum, even at finite lattice spacing. This formulation has been the subject of analytic investigation for some time and has reached the stage where large-scale simulations in QCD seem very promising. With the computational power available from the QCDSP computers, scientists are looking forward to an exciting time for numerical simulations of QCD.
Date: October 16, 1998
Partner: UNT Libraries Government Documents Department

Spectroscopy of B{sub s} and D{sub s} mesons

Description: We study B{sub s} and D{sub s} spectroscopy in quenched lattice QCD using the Fermilab approach to heavy quarks. We obtain results at four lattice spacings, a, using O(a)-improved Wilson quarks. We compare and contrast the various methods for heavy quarks on the lattice, discussing which methods work best for different physical systems and the ease with which calculations may be performed.
Date: January 1, 1998
Creator: MacKenzie, P.B.; Ryan, S.M. & Simone, J.N.
Partner: UNT Libraries Government Documents Department

Single identities for lattice theory and for weakly associative lattices

Description: We present a single identity for the variety of all lattices that is much simpler than those previously known to us. We also show that the variety of weakly associative lattices is one-based, and we present a generalized one-based theorem for subvarieties of weakly associative lattices that can be defined with absorption laws. The automated theorem-proving program OTTER was used in substantial way to obtain the results.
Date: March 13, 1995
Creator: McCune, W. & Padmanabhan, R.
Partner: UNT Libraries Government Documents Department

Introduction to lattice QCD

Description: The goal of the lectures on lattice QCD (LQCD) is to provide an overview of both the technical issues and the progress made so far in obtaining phenomenologically useful numbers. The lectures consist of three parts. The author`s charter is to provide an introduction to LQCD and outline the scope of LQCD calculations. In the second set of lectures, Guido Martinelli will discuss the progress they have made so far in obtaining results, and their impact on Standard Model phenomenology. Finally, Martin Luescher will discuss the topical subjects of chiral symmetry, improved formulation of lattice QCD, and the impact these improvements will have on the quality of results expected from the next generation of simulations.
Date: December 1998
Creator: Gupta, R.
Partner: UNT Libraries Government Documents Department

A lattice formulation of chiral gauge theories

Description: The authors present a method for formulating gauge theories of chiral fermions in lattice field theory. The method makes use of a Wilson mass to remove doublers. Gauge invariance is then restored by modifying the theory in two ways: the magnitude of the fermion determinant is replaced with the square root of the determinant for a fermion with vector-like couplings to the gauge field; a double limit is taken in which the lattice spacing associated with the fermion field is taken to zero before the lattice spacing associated with the gauge field. The method applies only to theories whose fermions are in an anomaly-free representation of the gauge group. They also present a related technique for computing matrix elements of operators involving fermion fields. Although the analyses of these methods are couched in weak-coupling perturbation theory, it is argued that computational prescriptions are gauge invariant in the presence of a nonperturbative gauge-field configuration.
Date: December 1, 1995
Creator: Bodwin, G.T.
Partner: UNT Libraries Government Documents Department