Measurement of the single-spin asymmetry in the reaction π~-d_↑ → π~0 X in the beam-fragmentation region at 40 GeV and p_(pT) of up to 2 GeV/c

摘要

The single-spin asymmetry A_N in the reaction π~- + d_↑ → π~0 + X in the beam-fragmentation region at the energy of 40 GeV was investigated by using the PROZA setup installed at the U-70 accelerator of the Institute for High Energy Physics (IHEP, Protvino). It was measured to be A_N = (13.6±2.6(stat.)±2.0(syst.))% in the intervals 0.7 < x_F < 1.0 and 1.0 < p_T < 1.8 GeV/c. The results agree with the asymmetry of π~0 mesons in the charge-exchange reaction π~- + p_↑ → π~0 + n at the same values of the transverse momentum and beam energy. The asymmetry in the reaction K~- + d_↑ → π~0 + X was simultaneously measured and found to be A_N = (11 ± 14)% for p_T 1.2 GeV/c.