Speaker
Description
The single transverse spin asymmetries in semi-inclusive DIS, with $P_{h\perp}$, i.e., the transverse momentum of the final detected hadron integrated over, are studied. At twist-3 level, it is found that the hadronic tensor at tree level contains two parts: the first one is non-derivative part, which is proportional to $\delta^2(P_{h\perp})$; the second one is derivative part, which is proportional to the derivative of this delta function. It is found that for derivative part the contribution of collinear gluons from polarized hadron can be
summed into gauge links in the same way as twist-2 factorization. Then, the virtual correction to derivative part is just the correction to quark form factor. According to this observation we constructed two observables, which are spin dependent and sensitive to derivative part of the hadronic tensor. With the virtual correction identical to the correction of quark form factor, the total one-loop divergences of these two observables, including real correction, are subtracted by the evolution kernels of twist-3 distribution functions exactly. This justifies collinear twist-3 factorization at one-loop level. We also present the complete one-loop results for these two observables.
