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Dynamical Anisotropic-Clover Lattice Production for Hadronic Physics C. Morningstar, CMU K. Orginos, College W&M J. Dudek, R. Edwards, B. Joo, D. Richards, C. Thomas, JLab S. Wallace, U. of Maryland N. Mathur, Tata Institute M. Peardon, S. Ryan, Trinity College AHM 2011

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Anisotropic Lattices for Nuclear Physics Hadronic spectroscopy –Hadron resonance determinations –Exotic meson spectrum and transition form-factors –HadSpec (Richards) Hadronic structure –3-D picture of hadrons from gluon & quark spin+flavor dist. –Ground & excited E&M transition FF-s –E&M polarizabilities of hadrons –HadSpec (Richards), EMC (Walker-Loud) Nuclear interactions –Nuclear processes relevant for stellar evolution –Hyperon-hyperon scattering –3 & 4 nucleon interaction properties –NPLQCD (Savage)

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N f =2+1 Anisotropic Clover: dynamical generation Current proposal: 40 3 x256 at m ¼ ~ 230 MeV, a s =0.1227fm, a t =0.035fm –Currently running on £ 256 at m ¼ ~ 230 & 383 MeV Future INCITE+ESP: 48 3 x384 at m ¼ ~ 140 MeV

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Priorities Current calculations at m ¼ ~ 230 MeV Finite volume effects: –Crucial for resonance/scattering extraction Chiral effects (large pion mass) appear large –Excited resonance: chiral extrap. problematic High statistics important (~10k traj. -> 1000 cfgs) Discretization effects appear small/negligible –Evidence via spectra of Subduced operators Priorities: 1.Physical 6fm box -> 48 3 x384 2.Second lattice ~500MeV pion mass

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Claim: discretization effects small/negligible Anisotropic gauge (Symanzik) action & fermion (Clover) action: –Fixed Clover coefficients c t and c s (Chen): –Bare gauge ° g fermion ° f anisotropy & bare quark mass m 0 Impose PCAC & rotational symmetry via SF techniques (m q = 0) O(a) effects in spectrum eliminated via on-shell improvement Discretization effects gggg 175 MeV 0 MeV ffff 175 MeV 0 MeV Anisotropies

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Claim: discretization effects small/negligible No dimension 5 rotation breaking terms –Also true for anisotropic actions Rotation breaking pushed to O(a 2 ) –True for both spectrum and wave-function (operator) overlaps Discretization effects

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Claim: discretization effects small/negligible In fact, rotation breaking negligible: Discretization effects arXiv: Basis of 3-quark ops with continuum J P Mix in lattice irreps Tiny off-diagonal mixing

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Claim: discretization effects small/negligible No discernible rotation breaking Discretization effects arXiv: Basis test: restrict operators Remarkable realization of rotational symmetry Determine J=7/2 for first time

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Scattering processes: range of interaction Volume effects: two varieties: exp(-m ¼ *L) effects [NPLQCD: ] Accessible momentum effects: –Determine partial-wave phase shifts ± L (E) vs. E(k 2 ) –Critical component in resonance determinations Volume effects I=2 ¼¼ L=0 & 2 scattering phase shift ± 0 (E) & ± 2 (E) First ever L=2 phase shift

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Extract resonance mass Can then chiral extrapolate Obviously want light pion masses Perilous waters: the excited J P = ½ + “Roper” Resonance mass and chiral extrapolations Four-fold degeneracy Big discrepancy: operator basis! Need ops featuring orbital structure & multi-particle ops

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Spin identified Nucleon & Delta spectrum 11 arXiv: m ¼ ~ 520MeV

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Spin identified Nucleon & Delta spectrum 12 Mass and overlaps: assign into multiplets arXiv: SU(6)xO(3) counting No parity doubling m ¼ ~ 520MeV

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Current plans Gauge production: –Emphasis on hadronic and nuclear physics –ORNL: INCITE time for 40 3 £ 256, m ¼ ~230MeV –ANL: extend 32 3 £ 256 ensembles Distillation(+variants) + subduction –Flexible: framework useful for 2-pt and 3-pt –In-place: multi-particle ops & annihilation diagrams Role expanding for GPU-s –Powerful resource for inversions –ECC+double precision -> handle contractions –Major software focus

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Backup

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Spectroscopy: exotic mesons

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