vectormeson

A vectormeson, also written vector meson, is a meson with total spin J = 1 and negative parity. Neutral members have J^PC = 1^−−. They are bound states of a quark and an antiquark in a vector (spin-1) configuration, typically an S-wave (L = 0) ground state with possible radial or orbital excitations. Common light vectormesons include the rho (ρ), omega (ω), and phi (φ) families, while heavier examples include charmonium states such as J/ψ and bottomonium states such as Υ.

Production and decays: Vector mesons couple to the electromagnetic current, so they appear as resonances in electron–positron annihilation and in photon-induced processes. They decay predominantly through the strong interaction into lighter hadrons; leptonic decays to e+e− or μ+μ− are allowed but with smaller branching fractions. The specific decay patterns reflect their quark content and available phase space.

Theoretical context: In quantum chromodynamics, vectormesons are qq̄ bound states described by nonperturbative dynamics. They are often treated with potential models or lattice QCD; the light ones form Regge trajectories, and the heavy ones (charmonium and bottomonium) can be approximated as nonrelativistic bound states. The vector-meson dominance model describes how photons couple to hadrons via mixing with vectormesons.

Notable examples and usage: ρ(770), ω(782), φ(1020) are the light vector mesons; J/ψ(1S) and Υ(1S) are well-known heavy-vector states. Excited states include ρ(1450), ρ(1700), φ(1680). Vector mesons play an important role in hadron spectroscopy, tests of QCD, and precision measurements of electromagnetic couplings.