Unconfined quarks and gluons

Abstract

We explore the possibility that fractionally charged colored quarks and electrically neutral colored gluons may exist as real particles. Our framework is a renormalizable, spontaneously broken version of color dynamics [quantum chromodynamics (QCD)], in which the gluons are given a common mass $\mu$ in the Lagrangian. Color SU(3) remains an exact global symmetry, and for small $\mu$ our understanding of color-singlet hadrons in QCD is unaltered. For small $\mu$ the masses of physical quarks and gluons are large: $O\left({\left(2\mathrm{}\pi {\alpha }^{\prime }\mu \right)}^{-1\mathrm{}}\right)$ with ${\alpha }^{\prime }$ the slope of Regge trajectories. There is at least one stable hadron for every representation of color SU(3). In the unbroken QCD limit ($\mu \to 0$) the conventional picture of color confinement is recovered. To implement quasiconfinement in detail we use the MIT bag model. For $\mu =0\mathrm{}$ this model describes confinement. For $\mu \ne 0$ it describes quasiconfinement with no further modification. Production cross sections for quarks and gluons turn out to be very small. Quark-nucleon and gluon-nucleon cross sections, on the other hand, are very large. Quarks and gluons have a large nuclear appetite: Sequential absorption of nucleons by a free quark is exothermic up to large values of total baryon number. If quarks are very heavy, primordial quarks left over from the big bang will be found in superheavy quark-nucleon complexes with large nonintegral charge and baryon number. Primordial gluons will have the appearance of integrally charged superheavy nucleon complexes.