Transverse single spin asymmetry inp+p↑→D+X

Collins Fragmentation and the Single Transverse Spin Asymmetry

Single Transverse - Spin Asymmetry in pp ↑ → πX and ep ↑ → πX

where the functions Ga(x1, x2), Eb(x ′ 1, x ′ 2) and Êc(z1, z2) are the twist-3 quantities representing, respectively, the transversely polarized distribution, the unpolarized distribution, and the fragmentation function for the pion. δqa(x) is the transversity distribution in p↑. a, b and c stand for the parton’s species, sum over which is implied. δqa, Eb and Êc are chiral-odd. Corresponding ...

Single transverse-spin asymmetry in Drell-Yan lepton angular distribution

We calculate a single transverse-spin asymmetry for the Drell-Yan lepton-pair’s angular distribution in perturbative QCD. At leading order in the strong coupling constant, the asymmetry is expressed in terms of a twist-3 quark-gluon correlation function T (V ) F (x1, x2). In our calculation, the same result was obtained in both light-cone and covariant gauge in QCD, while keeping explicit elect...

Single Transverse-Spin Asymmetry in Drell-Yan Production at Large and Moderate Transverse Momentum

We study the single-transverse spin asymmetry for the Drell-Yan process. We consider production of the lepton pair at large transverse momentum, q⊥ ∼ Q, where Q is the pair’s mass. The spin asymmetry is then of higher twist and may be generated by twist-three quark-gluon correlation functions. Expanding the result for q⊥ ≪ Q, we make contact with the transversemomentum-dependent QCD factorizati...

Transverse-Target Single-Spin Azimuthal Asymmetry in Hard Exclusive Electroproduction of Single Pions at HERMES

We present the analysis of data taken in the years 2002-2004 with the 27.56 GeV positron beam of the HERA storage ring at DESY and the internal transversely polarised hydrogen fixed target of the HERMES experiment. Events with a scattered positron and a produced pion are selected. Exclusive production of single pions, e+p → e+′nπ+, is ensured by requiring the missing mass in the event to be equ...