Electroproduction of the Roper resonance as a hybrid state

Electroproduction of the Roper resonance and the constituent quark model

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...

critical period effects in foreign language learning:the influence of maturational state on the acquisition of reading,writing, and grammar in english as a foreign language

since the 1960s the age effects on learning both first and second language have been explored by many linguists and applied linguists (e.g lennerberg, 1967; schachter, 1996; long, 1990) and the existence of critical period for language acquisition was found to be a common ground of all these studies. in spite of some common findings, some issues about the impacts of age on acquiring a second or...

Roper Electroproduction Amplitudes in a Chiral Confinement Model

A description of the Roper using the chiral chromodielectric model is presented and the transverse A1/2 and the scalar S1/2 helicity amplitudes for the electromagnetic Nucleon–Roper transition are obtained for small and moderate Q. The sign of the amplitudes is correct but the model predictions underestimate the data at the photon point. Our results do not indicate a change of sign in any ampli...

Completing the Picture of the Roper Resonance.

We employ a continuum approach to the three valence-quark bound-state problem in relativistic quantum field theory to predict a range of properties of the proton's radial excitation and thereby unify them with those of numerous other hadrons. Our analysis indicates that the nucleon's first radial excitation is the Roper resonance. It consists of a core of three dressed quarks, which expresses i...

Beam-Recoil Polarization Measurement of [superscript 0] Electroproduction on the Proton in the Region of the Roper Resonance