Polarised deep inelastic scattering accompanied by a forward jet as a probe of the ln(1/x) resummation

We argue that the production of forward jets in polarised deep inelastic scattering can be a useful tool for probing the double ln(1/x) resummation effects which control the polarised deep inelastic scattering for small values of the Bjorken parameter x. We solve the corresponding integral equations generating the double ln(1/x) resummation and calculate the differential structure function describing the forward jet production in the small x regime which can possibly be probed by the polarised HERA measurements. We show that these structure functions should exhibit the characteristic increase with decreasing x/xJ , where xJ denotes the longitudinal momentum fraction of the parent proton carried by a jet, and we quantify this increase. The idea of studying the deep inelastic ep scattering with an identified forward jet as a probe of the low x behaviour of QCD was proposed by Mueller [1]. Since then it has been successfully applied to the case of unpolarised deep inelastic scattering (DIS) [2, 3]. The Mueller’s proposal was to study the unpolarised deep inelastic events (x,Q) containing an identified forward jet (xJ , k 2 J), where the longitudinal momentum fraction xJ of the proton carried by a forward jet and jet transverse momentum squared k J were assumed to fulfill the conditions : xJ ≫ x, (1) k J ∼ Q . (2) e-mail: [email protected] e-mail: [email protected]