QCD analysis of leading-neutron production at HERA: Determination of neutron fracture functions

TL;DR

This paper presents a QCD-based analysis of leading-neutron production at HERA, extracting neutron fracture functions from experimental data and providing a phenomenological parametrization with uncertainty estimates.

Contribution

It introduces a novel extraction of neutron fracture functions using the fracture functions formalism and the Hessian method for uncertainty quantification.

Findings

Neutron fracture functions can be phenomenologically parametrized at the input scale.

Predictions based on extracted neutron FFs agree well with HERA data across various kinematic ranges.

Uncertainty estimates for neutron FFs and related structure functions are provided.

Abstract

The last two decades have seen a growing trend towards the experimental efforts at the electron-proton collider HERA in which have collected high precision data on the spectrum of leading neutron (LN) and leading-proton (LP) carrying a large fraction of the proton's energy. In our recent study [Phys. Rev. D \textbf{95} (2017), 074011], we have proposed an approach based on the Fractures Functions (FF) formalism and have extracted the neutron Fracture Functions (neutron FFs) from a global QCD analysis of LN production data measured by H1 and ZEUS collaborations at HERA. We have shown that considering the approach based on the framework of Fracture Functions, one could phenomenologically parametrize the neutron FFs at the input scale. In order to access the uncertainties for the obtained neutron FFs as well as the LN structure functions and cross section, associated with the uncertainties in the data, we have made an extensive use of the "Hessian method". Our theory predictions based on the obtained neutron FFs are in satisfactory agreement with all LN data analyzed, for a wide range of $\beta$ and $x_L$.