[**Light-cone sum rules for the $N\gamma\Delta$ transitions for real photons**]{}

[J. Rohrwild]{}\
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1.2cm [**Abstract:\
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Introduction
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The wish to understand the constituents of atomic nuclei, the nucleons, has been the driving force for a great many experiments and theoretical models. In particular the radiative nucleon-$\Delta$-transition has been in the focus of attention since 1979, when it was shown that a deformation of the nucleon-$\Delta$-system can entail non-vanishing electromagnetic (E2) and Coulomb (C2) quadrupole amplitudes [@Glashow:1979gp]. This breaks a selection rule laid down previously, which was derived in the first non relativistic quark model discussing the $E2$ amplitude [@Becchi] and which allows only magnetic dipole amplitudes (M1) in the $\gamma^*N\to \Delta$ transition.

The fact that the measurement of the electromagnetic properties of the transition can provide insights in the deviation of the nucleon or the $\Delta$ from spherical symmetry has resulted in numerous experiments covering a large range of accessible values for the photon virtuality $Q^2$. In the whole region up to $\sim 4\;{\rm GeV}^2$ the ratios $E2/M1$ and $C2/M1$ are found to be small and negative, especially $|E2/M1|$ is smaller than $5\%$ [@Frolov:1998pw; @Joo:2001tw; @Kunz:2003we; @Ungaro:2006df; @Sparveris:2006uk]. In the case of real photons, which is relevant for 