Nonperturbative treatment of gluons and pseudoscalar mesons in baryon spectroscopy

Abstract

We study baryon spectroscopy including the effects of pseudoscalar meson exchange and one gluon exchange potentials between quarks, governed by α s .The non-perturbative, hyperspherical method calculations show that one can obtain a good description of the data by using a quark-meson coupling constant that is compatible with the measured pion-nucleon coupling constant, and a reasonably small value of α s . Typeset using REVT E X

Effective Q-Q interactions in constituent quark models

“…If in our stochastic variational calculation we restrict the test-function space in a similar manner as DFM, we can roughly reproduce their results given in Ref. [7]. However, as it becomes evident from the fully converged results in Fig.…”

Quark-model study of few-baryon systems

“…Reference [44] presented a calculation with a small value for r 0 (r 0 = 0.0367 fm), the regularization parameter for the contact term of the OGE, and truncating the Hilbert space by means of a hyperspherical harmonic approach up to k = 2 excitations. Similar results were presented in reference [171]. These results were strongly criticized [172] by arguing that such a small value of r 0 would give rise to unstable values for the baryon masses.…”

“…1 423 2 641 4 643 4 68 2 419 4 622 8 601 6 21 3 418 6 587 12 570 8 12 8 578 16 551 10 2 10 562 20 540 12 0 12 558 areas to the experimental values including their uncertainties. As can be seen, apart from the energy difference between the positive and negative parity excitations of the nucleon, the spectrum is almost the same as those reported in [44] and [171]. These results make clear that the regularization depends on the model space in which the calculation is done and the parameter of this regularization should not be understood as a true parameter of the model Hamiltonian but instead as a free parameter to be fitted.…”

π−gluon exchange interaction between constituent quarks

“…α S ≃ 0.04 − 0.27, depending on the choice of screening parameter Λ). Careful numerical studies [19] of the baryon spectrum with hyperfine interaction models that are linear combinations of the single gluon and pion exchange interactions [20,21] indicate that α S has to be less than about 0.35 if the problem of incorrect ordering of the lowest positive and negative parity states is to be avoided.…”