Twist-3 Fragmentation Research Articles

Single transverse spin asymmetry for large- [formula omitted] pion production in semi-inclusive deep inelastic scattering

We study the single spin asymmetry (SSA) for the pion production with large transverse momentum p T in semi-inclusive deep inelastic scattering e p ↑ → e π X . We derive the twist-3 cross section formula for SSA, focussing on the soft-gluon-pole contributions associated with the twist-3 distribution for the nucleon and with the twist-3 fragmentation function for the pion. We present a simple estimate of the asymmetries due to each twist-3 effect from nucleon and pion, respectively, by fixing the overall strength of the relevant nonperturbative quantities by the data on the SSA A N in p ↑ p → π X collision.

Single transverse spin asymmetry in p↑ p → πX and ep↑ p → πX

Single transverse spin asymmetry for the pion production in pp and ep collisions is studied in the framework of collinear factorization. The soft-gluon pole contributions with twist-3 distribution and fragmentation functions are identified and its characteristic features are discussed.

Evolution of twist-3 fragmentation functions in multicolour QCD and the Gribov-Lipatov reciprocity

It is shown that twist-3 fragmentation functions in the large-$N_c$ limit of QCD obey the DGLAP evolution equations. The anomalous dimensions are found explicitly. The Gribov-Lipatov reciprocity is violated at the twist-3 level in the leading logarithmic approximation.