The amplitudes of the transition γ∗N → P11(1440) are calculated within light-front relativistic quark model assuming that the P11(1440) is the first radial excitation of the 3q nucleon state. The results are compared with those obtained in close approaches by other authors and with standard nonrelativistic calculations. One of the reasons for this study was to present all these results within u...

It is shown that the anomalously low-lying Roper states cannot be assigned as members of the 5Q antidecuplet or 5Q octet multiplets as suggested by Jaffe and Wilczek. A possible experimental discovery of the antidecuplet state Θ + (1540) [1] certainly disturbs a quiet life of hadron physics. Obviously there is a need not only to explain Θ + (1540) in a quark language (see, e.g. [2–4]), but also...

A parameter-free evaluation of the N −P11(1440) electromagnetic transition form factors is performed within a light-front constituent quark model, using for the first time the eigenfunctions of a mass operator which generates a large amount of configuration mixing in baryon wave functions. A one-body electromagnetic current, which includes the phenomenological constituent quark form factors alr...

The Roper resonance is described in a chiral version of the chromodielectric model as a cluster of three quarks in radial-orbital configuration (1s)2(2s)1, surrounded by π and σ-meson clouds and by a chromodielectric field which assures quark dynamical confinement. Radial profiles for all fields are determined self-consistently for each baryon. Transverse A1/2 and scalar S1/2 helicity amplitude...