The two-spin parameter A(LL) in inclusive pi-0 production by longitudinally-polarized protons and antiprotons on a longitudinally-polarized proton target has been measured at the 200 GeV Fermilab spin physics facility, for pi-0,s at X(F) = 0 with 1 less-than-or-equal-to p(t) less-than-or-equal-to 3 GeV/c. The results exclude, at the 95% confidence level, values of A(LL) (pp) > 0.1 and < -0.1, for pi-0,s produced by protons, and values of A(LL) (antiproton-antiproton) > 0.1 and < -0.2 for incident antiprotons. The relevance of A(LL) (pp) for the gluon spin density is discussed. The data are in good agreement with "conventional", small or zero, gluon polarization.
First results for the two-spin parameter ALL in pi0 production by 200 GeV polarized protons and antiprotons
1991
Abstract
The two-spin parameter A(LL) in inclusive pi-0 production by longitudinally-polarized protons and antiprotons on a longitudinally-polarized proton target has been measured at the 200 GeV Fermilab spin physics facility, for pi-0,s at X(F) = 0 with 1 less-than-or-equal-to p(t) less-than-or-equal-to 3 GeV/c. The results exclude, at the 95% confidence level, values of A(LL) (pp) > 0.1 and < -0.1, for pi-0,s produced by protons, and values of A(LL) (antiproton-antiproton) > 0.1 and < -0.2 for incident antiprotons. The relevance of A(LL) (pp) for the gluon spin density is discussed. The data are in good agreement with "conventional", small or zero, gluon polarization.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
