Strangeness production in deep inelastic positron - proton scattering at HERA

Abstract Measurements of K 0 meson and Λ baryon production in deep-inelastic positron-proton scattering (DIS) are presented in the kinematic range 10 Q 2 2 and 10 −4 x −2 . The measurements, obtained using the H1 detector at the HEPAcollider, are discussed in the light of possible mechanisms for increased strangeness productionat low Bjorken- x . Comparisons of the x F spectra, where x F is the fractional longitudinal momentum in the hadronic centre-of-mass frame, are made with results from electron-positron annihilation. The x F spectra and the K 0 “seagull” plot are compared with previous DIS results. The mean K 0 and Λ multiplicities are studied as a function of the centre-of-mass energy W and are observed to be consistent with a logarithmic increase with W when compared with previous measurements. A comparison of strangeness productionin diffractive and non-diffractive DIS is made. An upper limit of 0.9 nb, at the 95% confidence level, is placed on the cross section for QCD instantoninduced events.