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Roper from 2+1 Flavor Clover Fermions and Chiral Dynamics. Roper resonances from quenched approximation and 2+1 flavor Clover fermions Roper wavefunctions from overlap Flavor-singlet and flavor-octec Λ (1/2 - ) Attempt to understand the underline chiral dynamics. QCD Collaboration :
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Roper from 2+1 Flavor Clover Fermions and Chiral Dynamics • Roper resonances from quenched approximation and 2+1 flavor Clover fermions • Roper wavefunctions from overlap • Flavor-singlet and flavor-octec Λ (1/2-) • Attempt to understand the underline chiral dynamics QCDCollaboration: A. Alexandru, Y. Chen, T. Doi, S.J. Dong, T. Draper, F .X. Lee, K.F. Liu, D. Mankame, X.F. Meng, N. Mathur, T. Streuer Lattice 2008, July 15, 2008
Sequential Empirical Bayes Method Fitting of CSSM Data Y. Chen
Overlap fermion on quenched 16^3 x 28 lattices In the chirally improved fermion calculation (a=0.119 fm), the flavor-octet and flavor-singlet Λ(1/2-) are inverted.
Roper Radial excitation? q4q State? • Roper is seen on the lattice with three-quark interpolation field. • Weight : |<0|ON|R >|2 >|<0|ON|N>|2 > 0(point source, point sink) ∑ψ(x) ∑ON(x) ∑ψ(y) ∑ψ(z) Point sink Wall source <0|ON(0)|N><N| ∑ψ(x) ∑ψ(y) ∑ψ(z)|0 >>0 However,<0|ON(0)|R><R| ∑ψ(x) ∑ψ(y) | ∑ψ(z)|0 ><0 1S 2S
Conclusion • Baryon Spectrum is sensitive to fermion actions at finite a. • Dynamical fermion has a large effect on S11 and both singlet and octet Λ(1/2-) for the Clover action. • In addition to chiral logs in mπand mK, Roper and Λ(1/2-) are good cases to study chiral dynamics with different fermion actions.