Transverse Quark Polarization in Large-pTReactions,e+e−Jets, and Leptoproduction: A Test of Quantum Chromodynamics

We point out that the polarization $P$ of a scattered or produced quark is calculable perturbatively in quantum chromodynamics for $e^{+}{e}^{-}\to q\overline{q}$, large-$p_T$ hadron reactions, and large-$Q^2$ leptoproduction, and is infrared finite. The quantum-chromodynamics prediction is that $P=0\mathrm{}$ in the scaling limit. Experimental tests are or will soon be possible in $\mathrm{pp}\to \Lambda X$ [where presently $P\left(\Lambda \right)\simeq 25\%$ for $p_T>2\mathrm{}$ GeV/c] and in $e^{+}{e}^{-}\to \mathrm{quark}\mathrm{jets}$.