Excited state nucleon spectrum with two flavors of dynamical fermions

Bulava, John; Edwards, Robert G.; Engelson, Eric; Foley, J.; Joó, Bálint; Lichtl, Adam; Lin, Huey-Wen; Mathur, Nilmani; Morningstar, Colin; Richards, David; Wallace, S.J.

doi:10.1103/physrevd.79.034505

Cited by 87 publications

(123 citation statements)

References 45 publications

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“…Correlation matrices composed of traditional three-quark operators have been very successful in revealing a dense spectrum of baryon excited states in lattice QCD [1][2][3][4][5][6][7][8][9][10][11][12]. However the lowest lying multi-particle scattering state thresholds are often absent in the observed spectra.…”

Section: Introductionmentioning

confidence: 99%

Searching for low-lying multi-particle thresholds in lattice spectroscopy

Mahbub¹,

Kamleh²,

Leinweber³

et al. 2014

Annals of Physics

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We explore the Euclidean-time tails of odd-parity nucleon correlation functions in a search for the S -wave pionnucleon scattering-state threshold contribution. The analysis is performed using 2 + 1 flavor 32 3 × 64 PACS-CS gauge configurations available via the ILDG. Correlation matrices composed with various levels of fermion source/sink smearing are used to project low-lying states. The consideration of 25,600 fermion propagators reveals the presence of more than one state in what would normally be regarded as an eigenstate-projected correlation function. This observation is in accord with the scenario where the eigenstates contain a strong mixing of single and multi-particle states but only the single particle component has a strong coupling to the interpolating field. Employing a twoexponential fit to the eigenvector-projected correlation function, we are able to confirm the presence of two eigenstates. The lower-lying eigenstate is consistent with a Nπ scattering threshold and has a relatively small coupling to the three-quark interpolating field. We discuss the impact of this small scattering-state contamination in the eigenvector projected correlation function on previous results presented in the literature.

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Section: Introductionmentioning

confidence: 99%

Searching for low-lying multi-particle thresholds in lattice spectroscopy

Mahbub¹,

Kamleh²,

Leinweber³

et al. 2014

Annals of Physics

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“…[3], and nucleon results for two flavors of dynamical quarks appeared in Ref. [4]. A survey of excited-state energies in small volume for the isovector mesons and kaons using N f = 2 + 1 dynamical quarks was given in Ref.…”

Section: Introductionmentioning

confidence: 99%

Extended hadron and two-hadron operators of definite momentum for spectrum calculations in lattice QCD

et al. 2013

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Multi-hadron operators are crucial for reliably extracting the masses of excited states lying above multi-hadron thresholds in lattice QCD Monte Carlo calculations. The construction of multi-hadron operators with significant coupling to the lowest-lying multi-hadron states of interest involves combining single hadron operators of various momenta. The design and implementation of large sets of spatially-extended single-hadron operators of definite momentum and their combinations into two-hadron operators are described. The single hadron operators are all assemblages of gaugecovariantly-displaced, smeared quark fields. Group-theoretical projections onto the irreducible representations of the symmetry group of a cubic spatial lattice are used in all isospin channels. Tests of these operators on 24 3 × 128 and 32 3 × 256 anisotropic lattices using a stochastic method of treating the low-lying modes of quark propagation which exploits Laplacian Heaviside quark-field smearing are presented. The method provides reliable estimates of all needed correlations, even those that are particularly difficult to compute, such as ηη → ηη in the scalar channel, which involves the subtraction of a large vacuum expectation value. A new glueball operator is introduced, and the evaluation of the mixing of this glueball operator with a quark-antiquark operator, ππ, and ηη operators is shown to be feasible.

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“…In a series of papers [1,2,3,4,5,6], we have been striving to compute the finite-volume stationary-state energies of QCD using Markov-chain Monte Carlo integration of the QCD path integrals formulated on a space-time lattice. In this talk, our progress made during the past year is described.…”

Section: Introductionmentioning

confidence: 99%

Excited isovector mesons using the stochastic LapH method

Morningstar¹,

Fahy²,

Jhang³

et al. 2015

Proceedings of the 32nd International Symposium on Lattice Field Theory — PoS(LATTICE2014)

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The spectrum of excited isovector mesons is studied using a 32 3 × 256 anisotropic lattice with u, d quark masses set to give a pion mass near 240 MeV. Results in the bosonic isovector nonstrange symmetry channels of zero total momentum are presented using correlation matrices of unprecedented size. In addition to spatially-extended single-meson operators, large numbers of two-meson operators are used, involving a wide variety of light isovector, isoscalar, and strange meson operators of varying relative momenta. All needed Wick contractions are efficiently evaluated using a stochastic method of treating the low-lying modes of quark propagation that exploits Laplacian Heaviside quark-field smearing. Level identification is discussed.

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Excited state nucleon spectrum with two flavors of dynamical fermions

Cited by 87 publications

References 45 publications

Searching for low-lying multi-particle thresholds in lattice spectroscopy

Searching for low-lying multi-particle thresholds in lattice spectroscopy

Extended hadron and two-hadron operators of definite momentum for spectrum calculations in lattice QCD

Excited isovector mesons using the stochastic LapH method

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