V. L. Rykov

Observation of significant spin effects in hard collisions at 40 GeV/c

Abstract A single-spin asymmetry in the inclusive π 0 production at small x F was measured. In the experiment 40 GeV/c π − mesons were incident on transversely polarized protons and deutrons. An asymmetry of (40–50)% has been revealed in the hard scattering region.

Polarization in the reaction π−p → π0n at 40 GeV/c

Abstract The paper presents results on measuring the polarization in the reaction π − p→ π 0 n at 40 GeV/ c in the 4-momentum transfer range 0 t |⩽2 (GeV/ c ) 2 . The results based on the statistics of about 2.2 million recorded events made it possible to observe a noticeable value and complex structure in the polarization behaviour up to | t |⩽2 (GeV/ c ) 2 .

Polarization parameters in the reactions π−p↑→ηn and π−p↑→η′n at 40 GeV/c

The polarization parameter in the reactions π−p→ηn and π−p→η′n at 40 GeV/c with −t ranging from 0 to 2.6 (GeV/c)2 and 1.0 (GeV/c)2, respectively, was measured in experiments using a propanediol polarized target. Only gamma particles from the neutral meson decay were detected. The polarization parameter of the first reaction turns out to be negative in a widet interval (0.05<−t<1.6 (GeV/c)2) and probably changes its sign at larger values oft. The average value of the polarization parameter of the second reaction is equal to −17±8)% in the region 0.05<−t<0.5 (GeV/c)2.

Search for azimuthal asymmetry of π0‐meson production in beam fragmentation region on polarized protons and deuterons

The inclusive production of {pi}{sup 0}s in the interaction of unpolarized {pi}{sup {minus}}, {ital k}{sup {minus}}, and antiproton beams with polarized proton and deuteron targets has been studied at IHEP. The absolute value of the asymmetry for {pi}{sup 0} production in the polarized proton and deuteron targets is between zero and fiften percent for large {ital x}={ital P}*/{ital P}*{sub max} and small {ital P}{sub {ital t}} and independent on the quark flavor. Results are presented and compared with theoretical calculations. (AIP)

Measurement of the spin asymmetry of cumulative proton production at 90° in the reaction πd↑→px at 40 GeV by using a polaraized deuterium target

Spin asymmetry of the protons emitted in the (85–95)°L.S. angular region in the π+d↑→p+x reaction was measured using a deuteron frozen‐spin target and a 40 GeV/c pion beam. The experimental results for (0.3–0.7) GeV/c momenta of the protons asre discussed and compared with the predictions of some models of cumulative particle production.

Revealing of essential spin effects in hard collisions at 40 GeV

A 40%‐asymmetry has been revealed in the hard scattering region at 40 GeV. Systematic errors in the experiment are noticeable. The observed effect requires detailed discussion of the production mechanisms.