Electric quadrupole photoexcitation of Δ33 and experimental confirmation of the tensor interaction of quarks
Grushin V. F. , Leikin E. M. , Rotvain A. Ya. , Shikanyan A. A.
An energy-independent multipole analysis based on experimental data exclusively on the photoproduction of pions at protons demonstrates a resonant electric quadrupole transition Υρ-^Δ 3^. This result confirms that the nucleon and the isobar have a cZ-wave admixture due to a tensor interaction between quarks.