Spin effects in inclusive Lambda production using 200 GeV polarized protons

[摘要] We have used the Fermilab Polarized Proton Beam Facility to measure the Analyzing Power and the Depolarization parameters of the inclusive reaction p$uparrow$ + p $o$ $Lambda$ + X. The $Lambda$ Polarization was also observed as a consistency check against existing data. The kinematic range of the accepted $Lambda$'s centers at $xsb{F}$ = 0.5 and $psb{t}$ = 0.6 $GeV/c$, with $xsb{F}$ reaching up to 0.8 and $psb{T}$ up to 1.1 $GeV/c$. The Polarization was found to be consistent with previous measurements. The Analyzing Power and Depolarization were found to be near zero at all kinematics bins and in agreement with the only set of existing data which were measured at much lower energies. Beam energy independency was confirmed.The results from our $Lambda$ data do not contradict predictions made by the Thomas precession model which implies that the proton's spin is carried by the valence quarks.

[发布机构] Rice University

[效力级别] physics