N-to-Δ electromagnetic-transition form factors from lattice QCD
Date
2005Source
Physical Review LettersVolume
94Issue
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The magnetic dipole (M1), the electric quadrupole (E2), and the Coulomb quadrupole (C2) amplitudes for γN → Δ are calculated in quenched lattice QCD. Using a new method, which combines an optimal choice of interpolating fields for the Δ and an overconstrained analysis, we obtain statistically accurate results for the dipole form factor and for the ratios REM = E2/M1 and RSM = C2/M1, up to momentum transfer squared 1.5 GeV2. We show for the first time, using lattice QCD, that both REM and RSM are nonzero and negative, in qualitative agreement with experiment and indicating the presence of deformation in the N/Δ system. © 2005 The American Physical Society.