Single Spin Asymmetry at Large x_F and k_T

Abstract

The large single spin asymmetries observed at high momentum fractions x_F and transverse momenta k_T in p^\uparrow p -> π(x_F,k_T)+X as well as in pp -> Λ^\uparrow(x_F,k_T)+X suggest that soft helicity flip processes are coherent with hard scattering. Such coherence can be maintained if x_F -> 1 as k_T -> \infty, while k_T^2(1-x_F) \sim Λ_QCD^2 stays fixed. The entire hadron wave function, rather than a single quark, then contributes to the scattering process. Analogous coherence effects have been seen experimentally in the Drell-Yan process at high x_F. We find that the p^\uparrow p -> π(x_F,k_T)+X production amplitudes have large dynamic phases and that helicity flip contributions are unsuppressed in this limit, giving rise to potentially large single spin asymmetries.

11 pages, 2 figures. v2: References and a preprint number added. Calculation of section 4 modified. v3: Minor changes in text. Version to be published in JHEP

References in corpus (7)

• Single-spin asymmetries in semi-inclusive deep-inelastic scattering on a transversely polarized hydrogen target
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Cited by in corpus (10)

• Parton Fragmentation Functions
• Azimuthal and Single Spin Asymmetries in Hard Scattering Processes
• Fragmentation contribution to the transverse single-spin asymmetry in proton-proton collisions
• Transverse single spin asymmetries at small x and the anomalous magnetic moment
• Single-spin asymmetries in inclusive deep inelastic scattering and multiparton correlations in the nucleon
• Analysis of the double-spin asymmetry A_LT in inelastic nucleon-nucleon collisions
• Double spin asymmetry A_{LT} in direct photon production
• Transverse spin observables in hard-scattering hadronic processes within collinear factorization
• The Dirac Form Factor Predicts the Pauli Form Factor in the Endpoint Model
• Spin asymmetry at large x_F and k_T