Hadron masses in a gauge theory

TLDR

The standard gauge model includes four fractionally charged quark types in three colors coupled to massless gluons, with quarks confined in colorless hadrons by a long‑range spin‑independent force that realizes infrared slavery. The study investigates how the standard gauge model informs hadron spectroscopy, arguing that short‑range quark‑quark interactions can be approximated as Coulomb‑like and developing a qualitative understanding of mass‑splitting features such as the Σ−Λ difference. The authors employ asymptotic freedom to model short‑range quark‑quark forces as Coulomb‑like, use this framework to explain mass‑splitting phenomena, and apply it to predict charmed meson and baryon masses from newly observed narrow boson resonances. The model reproduces known quark‑model mass relations, predicts new relations that are well satisfied, and successfully forecasts the masses of charmed mesons and baryons based on newly discovered narrow boson resonances.

Abstract

We explore the implications for hadron spectroscopy of the "standard" gauge model of weak, electromagnetic, and strong interactions. The model involves four types of fractionally charged quarks, each in three colors, coupling to massless gauge gluons. The quarks are confined within colorless hadrons by a long-range spin-independent force realizing infrared slavery. We use the asymptotic freedom of the model to argue that for the calculation of hadron masses, the short-range quark-quark interaction may be taken to be Coulomb-like. We rederive many successful quark-model mass relations for the low-lying hadrons. Because a specific interaction and symmetry-breaking mechanism are forced on us by the underlying renormalizable gauge field theory, we also obtain new mass relations. They are well satisfied. We develop a qualitative understanding of many features of the hadron mass spectrum, such as the origin and sign of the $\ensuremath{\Sigma}\ensuremath{-}\ensuremath{\Lambda}$ mass splitting. Interpreting the newly discovered narrow boson resonances as states of charmonium, we use the model to predict the masses of charmed mesons and baryons.