strange particle

[′strānj ′pard·ə·kəl]

(particle physics)

A hadron whose strangeness number is not zero, for example, a K-meson or a Σ-hyperon.

The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Strange Particle

a hadron—that is, a strongly interacting particle—whose strangeness number 5 is not zero. By contrast, S = 0 for ordinary, or nonstrange particles (pions, protons, and neutrons). Kaons, hyperons, and some resonances are strange particles.

All strange particles are unstable. Strange resonances decay very rapidly through strong interactions and have lifetimes of the order of 10^–23 sec. Since strangeness is conserved in strong interactions, the total strangeness of the decay products is equal to the strangeness of the original particle. The other strange particles are quasi-stable and decay relatively slowly through weak interactions. The lifetimes of such particles are of the order of 10^–8–10^–10 sec. The decay products in this case may be leptons, nonstrange particles, or strange particles of lesser strangeness. The total strangeness of the decay products here differs from the strangeness of the original particle by 1.

Strange particles can be produced with high probability in collisions of ordinary hadrons. In this case, however, they must be produced in pairs (or in larger quantities) so that their total strangeness is equal to zero. Strange particles decay into ordinary particles with a very low probability. This “strangeness” in the behavior of the particles is the reason for their name.

A. A. KOMAR

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References in periodicals archive

Kennedy et al., "Neutral strange particle production in neutrino and antineutrino charged current interactions on protons," Zeitschrift fur Physik C, vol.

Aderholz et al., "Neutral strange particle production in neutrino and antineutrino chargedcurrent interactions on neon," Physical Review D, vol.

The NOMAD experiment at CERN

Anticic et al., "Anisotropic flow of strange particles at SPS" in Proceedings of the 3rd Edition of the Conference Critical Point and the Onset of Deconfinement (CPOD '06), p.

On particle production in lead-gold collision and azimuthal anisotropy at top SPS energy

For rather complicated theoretical reasons, physicists expect that a quark-gluon plasma will emit a large number of the class of particles called strange particles. The name "strange' was applied in the 1950s, when the first of these particles were found, because their behavior seemed strange at the time.

Another experiment, by 12 institutions ranging from the Punjab to Pittsburgh and from Athens to Bergen (Norway), will look for strange particles with a time-projection chamber.

Quark-gluon plasma

Thus, while physicists in the United States and Europe approach the frontier of nuclear physics by colliding nuclei with other nuclei, the Japanese intend to see what happens when nuclei contain particles of the class called strange particles instead of some of their usual neutrons and protons.

Strange nuclei in Japan

So far, many experimental results from the Super Proton Synchrotron (SPS) and Relativistic Heavy Ion Collider (RHIC) have shown the enhancement of strange particles [2].

Angular dependence of [phi] meson production for different photon beam energies