The magnetic dipole, the electric quadrupole and the Coulomb quadrupole amplitudes for the transition gamma Nto Delta are calculated in quenched lattice QCD at beta=6.0 with Wilson fermions. Using a new method combining an optimal combination of interpolating fields for the $Delta$ and an overconstrained analysis, we obtain statistically accurate results for the dipole form factor and for the ratios of the electric and Coulomb quadrupole amplitudes to the magnetic dipole amplitude, R_{EM} and R_{SM}, up to momentum transfer squared 1.5 GeV^2. We show for the first time using lattice QCD that both R_{EM} and R_{SM} are non-zero and negative, in qualitative agreement with experiment and indicating the presence of deformation in the N- Delta system.
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