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In a relativistic quark model we study the structure of the $N(1710)$ resonance, and the $gamma^ast N to N(1710)$ reaction focusing on the high momentum transfer region, where the valence quark degrees of freedom are expected to be dominant. The $N(1710)$ resonance, a state with spin 1/2 and positive parity ($J^P = frac{1}{2}^+$), can possibly be interpreted as the second radial excitation of the nucleon, after the Roper, $N(1440)$. We calculate the $gamma^ast N to N(1710)$ helicity amplitudes, and predict that they are almost identical to those of the $gamma^ast N to N(1440)$ reaction in the high momentum transfer region. Thus, future measurement of the helicity amplitudes for the $gamma^ast N to N(1710)$ reaction can give a significant hint on the internal structure of the $N(1710)$ state.
The $gamma^{(ast)}+p to N(1535) tfrac{1}{2}^-$ transition is studied using a symmetry-preserving regularisation of a vector$,otimes,$vector contact interaction (SCI). The framework employs a Poincare-covariant Faddeev equation to describe the initial
The collinear factorization framework allows to describe the exclusive photoproduction of a $gamma,rho$ pair in the generalized Bjorken regime in terms of a perturbatively calculable coefficient function and universal generalized parton distributions
We present a new method to determine the momentum dependence of the N to Delta transition form factors and demonstrate its effectiveness in the quenched theory at $beta=6.0$ on a $32^3 times 64$ lattice. We address a number of technical issues such a
We report a new extraction of nucleon resonance couplings using pi- photoproduction cross sections on the neutron. The world database for the process gamma n --> pi- p above 1 GeV has quadrupled with the addition of new differential cross sections fr
We have proposed to use an effective theory to describe interactions of an $Nbar N$-system. The effective theory can be constructed in analogy to the existing effective theory for an $NN$-system. In this work we study the next-to-leading order correc