(eng)
The production of the neutral strange hadrons $K^{0}_{S}$, $\Lambda$ and
$\bar{\Lambda}$ has been measured in $ep$ collisions at HERA using the ZEUS
detector. Cross sections, baryon-to-meson ratios, relative yields of strange
and charged light hadrons, $\Lambda$ ($\bar{\Lambda}$) asymmetry and
polarization have been measured in three kinematic regions: $Q^2 > 25 \gev^2$;
$5 < Q^2 < 25 \gev^2$; and in photoproduction ($Q^2 \simeq 0$). In
photoproduction the presence of two hadronic jets, each with at least $5 \gev$
transverse energy, was required. The measurements agree in general with Monte
Carlo models and are consistent with measurements made at $e^+ e^-$ colliders,
except for an enhancement of baryon relative to meson production in
photoproduction.
Comment: 40 pages, 20 figures, 1 table, minor revisions, accepted by European
Physical Journal C
