nonstrange

Nonstrange is a term used in particle physics to describe hadrons whose valence quark content contains no strange quarks. Strangeness is a quantum number assigned to quarks, with the strange quark carrying strangeness S = -1 and the antistrange quark S = +1. Hadrons that contain no strange quarks have S = 0 and are referred to as nonstrange. The designation applies to both mesons and baryons and can also apply to states that include charm or bottom quarks, provided no strange quark is present in the valence content.

Examples of nonstrange mesons include the pions (π+, π0, π−) and the rho mesons (ρ+, ρ0, ρ−), as well as the omega meson (ω), which are composed primarily of up and down quarks. Nonstrange baryons include the nucleons—the proton (p) and neutron (n)—and the Delta isobars (Δ++, Δ+, Δ0, Δ−). In contrast, hadrons containing at least one strange quark, such as kaons (K) and hyperons (Λ, Σ, Ξ, Ω), carry nonzero strangeness and are described as strange or multistrange.

In hadron spectroscopy, nonstrange states are organized by quantum numbers such as isospin and total angular momentum, in addition to strangeness. The concept is used to categorize production mechanisms and decay patterns and to distinguish light-flavor content. While the term denotes zero strangeness in valence quarks, real hadrons may exhibit small strange components due to quantum fluctuations or mixing, though their valence content remains nonstrange.

Note: In general English usage, nonstrange is an ordinary compound adjective meaning not strange or unfamiliar; in physics, it carries a precise technical meaning related to strangeness.