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The N to Delta electromagnetic transition form factors from Lattice QCD

C. Alexandrou·Ph. de Forcrand·H. Neff·J. W. Negele·W. Schroers·A. Tsapalis
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Abstract

The magnetic dipole, the electric quadrupole and the Coulomb quadrupole amplitudes for the transition γN\to Δare calculated in quenched lattice QCD at β=6.0 with Wilson fermions. Using a new method combining an optimal combination of interpolating fields for the $Δ$ 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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C. Alexandrou, Ph. de Forcrand, H. Neff, J. W. Negele, W. Schroers, A. Tsapalis. 2004-09-19. The N to Delta electromagnetic transition form factors from Lattice QCD. https://doi.org/10.1103/physrevlett.94.021601

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