On the scalar meson exchange in the baryon spectra

We explore the role of a scalar meson exchange interaction between quarks in a semirelativistic constituent quark model where the quarks are also subject to a linear confinement. We study how the spectrum evolves when the strength of the scalar meson exchange increases. Our results are relevant to the long-standing problem of the relative position of the first positive parity (Roper resonance) and the first orbitally excited states in the baryon spectrum. (author)