Geometric scaling in leading neutron events at HERA

This analysis provides new fits of the Golec-Biernat , Wusthoff model and the impact parameter -dependent saturation model (bSat or IP-Sat) to the leading neutron structure function HERA data in one pion exchange approximation. Both parametrizations of the dipole cross section provide good descriptions of the considered data. It is shown here for the first time that the experimental leading neutron production HERA data exhibits geometric scaling, which in this context means that the total gamma*pi* cross section is a function of only one dimensionless variable tau = Q2/Q2s(x). The geometric scaling region extends over a broad range of Q2 and can be attributed to the presence of a saturation boundary which manifests at Q2 >= Q2s. The scaling behavior in leading neutron events is profoundly similar to what has been observed for the inclusive DIS events.

Automated summary

This analysis uses new fits of the Golec-Biernat, Wusthoff model and the impact parameter-dependent saturation model (bSat or IP-Sat) to describe the leading neutron structure function HERA data. The dipole cross section parametrizations provide good descriptions of the data. It is shown for the first time that the experimental leading neutron production HERA data exhibits geometric scaling, indicating a saturation boundary at Q² >= Q²s.