The Constituent Quark Model Revisited - Quark Masses, New Predictions for Hadron Masses and KN Pentaquark

TL;DR

This paper revisits the constituent quark model, extending it to heavy flavors, deriving new mass relations, and proposing an interpretation for the recently observed theta^+ pentaquark as an exotic state with specific quantum numbers.

Contribution

It introduces new mass relations for heavy quarks, constructs a potential model explaining quark mass decreases, and proposes a novel pentaquark interpretation consistent with experimental data.

Findings

Mass relations hold for mesons and baryons with heavy flavors.

Potential model qualitatively reproduces quark mass decrease pattern.

Proposed pentaquark interpretation matches experimental mass estimates.

Abstract

Prompted by the recent surprising results in QCD spectroscopy, we extend to heavy flavors the hadron mass relations showing that the constituent quark mass differences and ratios have the same values when obtained from mesons and baryons. We obtain several new successful relations involving heavy quarks and provide some related predictions. We discuss in detail the apparent sharp decrease in m_s and m_c, when a light partner quark in a meson is replaced by a heavy one and construct a potential model which qualitatively reproduces this pattern through wave function effects. We apply these ideas to the recently discovered theta^+ exotic KN resonance and propose its interpretation as a novel kind of a pentaquark with an unusual color structure, J^P=1/2^+, I=0 and an antidecuplet of SU(3)_f. A rough mass estimate of this pentaquark is close to experiment.