engleski

Single spin asymmetries in ultraperipheral p↑A collisions

We suggest inclusive hadron production in ultraperipheral proton-nucleus collisions (UPCs) p↑A → hAX as a new channel to investigate single spin asymmetries, in particular, to test the assumed dominance of the contribution from twist-3 fragmentation functions. The UPC cross sections are obtained by considering the photoproduction limit of semi-inclusive deep inelastic scattering. In particular, we find simple formulas for the polarized UPC cross sections in the collinear twist-3 framework. We then numerically calculate the fragmentation contribution to single spin asymmetry in p↑A → πAX at √s = 200 GeV and find a few percent asymmetry in the forward region.

Single spin asymmetries

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