The electromagnetic nucleon to $\Delta$ transition form factors are evaluated using two degenerate flavors of dynamical Wilson fermions and using dynamical sea staggered fermions with domain-wall valence quarks. The two subdominant quadrupole form factors are evaluated for the first time in full QCD to sufficient accuracy to exclude a zero value, which is taken as a signal for deformation in the nucleon-$\Delta$ system. For the Coulomb quadrupole form factor the unquenched results begin to deviate from the quenched results at low $q^2$ indicating that dynamical lattice results are closer to experiment. This can be taken as a first confirmation of the expected importance of pion cloud contributions on this quantity.

• Received 25 October 2007

DOI:https://doi.org/10.1103/PhysRevD.77.085012