Polarized parton distributions and non-leading reggeons
نویسنده
چکیده
The small x behaviour of polarized parton distributions is related to non-leading reggeons in the framework of the high-energy effective action. Double-logarithmic contributions to the reggeon interaction beyond the ones included in the GLAP equation are encountered in all polarized parton distributions. The transversity distributions of quarks and gluons behave similar at small x. 1 Parton distributions For analyzing the small-x behaviour of structure functions or parton distributions it is appropriate to consider the t-channel exchange in the corresponding forward scattering amplitutes. Owing to polarization effects the P parity and the minimal angular momentum are the relvant t-channel quantum numbers. The unpolarized parton distributions are related to positive parity exchange (V), the helicity asymmetry distributions to negative parity exchange (A). The second type of polarized parton distributions, the transverse polarization asymmetries or transversities (T) are related to angular momentum 1 (quark transversity) or 2 (gluon transversity) exchange.
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