Production of strange particles in antineutrino interactions at the CERN PS

We have studied neutral strange particle production in the bubble chamber Gargamelle filled with propane and exposed to antineutrinos from the CERN PS. Cross sections are presented for Λ, Σ⁰ and K⁰ production. Associated production reactions (ΔS = 0) have been observed in the charged and the neutral current channels. From 45 candidates for the quasi-elastic reaction $\text{ν}\text{p}\text{→ μ}{}^{\mathrm{+}}\text{Λ}$, on bound and free protons, estimates of the axial transition form factor M_A have been made using the total cross section and the t distribution. The weighted average from the two methods is M_A = 862 ± 190 MeV. From a subsample of 15 candidates for $\text{ν}$ interactions on free protons in propane, with (28±6)% background from $\text{ν}$ interactions on bound protons, we obtain M_A = 883 ± 243 MeV. The polarization of the Λ hyperons has been studied for the quasi-elastic reaction. We observe a significant Λ polarization in the production plane, normal to the Λ line of flight. The observed polarizations agree well with the predicted theoretical polarizations without any contribution from second-class axial coupling.     

An update analysis of deep-inelastic scattering data: A first indication of radiative correction effects?

The results of a new detailed analysis of all data of

-induced deep-inelastic scattering, inclusive of radiative correction effects, is reported. A remarkable improvement in determining the (squared) chiral coupling constants is obtained. Analyzed in terms of the SU(2)_L × U(1) parameters ? and sin²?_w they give ? = 1.001±0.012±0.008 and sin²?_w = 0.215±0.014±0.008. By a comparison with the results obtained without the inclusion of radiative corrections, a weak, but significant, indication about them can be argued.