Abstract
The $E2/M1$ ratio (EMR) of the \ensuremath{\Delta}(1232) is extracted from the world data in pion photoproduction by means of an effective Lagrangian approach (ELA). This quantity has been derived within a crossing symmetric, gauge invariant, and chiral symmetric Lagrangian model which also contains a consistent modern treatment of the \ensuremath{\Delta}(1232) resonance. The bare $s$-channel \ensuremath{\Delta}(1232) contribution is well isolated and final state interactions (FSI) are effectively taken into account fulfilling Watson's theorem. The obtained EMR value, EMR $=(\ensuremath{-}1.30\ifmmode\pm\else\textpm\fi{}0.52)$%, is in good agreement with the latest lattice QCD calculations [Phys. Rev. Lett. 94, 021601 (2005)] and disagrees with results of current quark model calculations.
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