Abstract
The current analysis aims to present the results of a QCD analysis of diffractive parton distribution functions (diffractive PDFs) at next-to-leading order (NLO) accuracy in perturbative QCD. In this new determination of diffractive PDFs, we use all available and up-to-date diffractive deep inelastic scattering (diffractive DIS) datasets from H1 and ZEUS Collaborations at HERA including the most recent H1/ZEUS combined measurements. In this analysis, we consider the heavy quark contributions to the diffractive DIS in the so-called framework of {\tt FONLL} general mass variable flavor number scheme (GM-VFNS). The uncertainties on the diffractive PDFs are calculated using the standard "Hessian error propagation" which served to provide a more realistic estimate of the uncertainties. This analysis are enriched, for the first time, by including the nonperturbative higher twist (HT) effects in the calculation of diffractive DIS cross sections which are particularly important at large-$x$ and low $Q^{2}$ regions. Then, the stability and reliability of the extracted diffractive PDFs are investigated upon inclusion of HT effects. We discuss the novel aspects of the approach used in this QCD fit, namely, optimized and flexible parameterizations of diffractive PDFs, the inclusion of HT effects, and considering the recent H1/ZEUS combined dataset. Finally, we present the extracted diffractive PDFs with and without the presence of HT effects, and discuss the fit quality and the stability upon variations of the kinematic cuts and the fitted datasets. We show that the inclusion of HT effects in diffractive DIS can improve the description of the data which leads, in general, to a very good agreement between data and theory predictions.
Highlights
Over the past few decades, it has been known that the parton distribution functions (PDFs) of nucleons are an essential ingredient for the interpretation and QCD phenomenology of hadron structure in high-energy experiments such as the deep-inelastic lepton-nucleon scattering and hadron-hadron collisions
The current analysis aims to clarify whether the inclusion of nonperturbative higher twist (HT) effects can affect the QCD analysis of diffractive deep-inelastic scattering (DIS) data and can fill a gap in the QCD analysis of diffractive PDFs in literature
II, we introduce the theoretical framework and kinematical variables used for the definition of diffractive DIS processes, diffractive structure functions, and diffractive reduced cross sections
Summary
Over the past few decades, it has been known that the parton distribution functions (PDFs) of nucleons are an essential ingredient for the interpretation and QCD phenomenology of hadron structure in high-energy experiments such as the deep-inelastic lepton-nucleon scattering (lp DIS) and hadron-hadron collisions. Despite the active experimental and theoretical investigations, the determination of PDFs along with their uncertainties through a global QCD analysis is still an important topic in high-energy physics. We refer the reader to Refs. [1,2,3,4,5,6] for introductory texts on the fundamentals of QCD factorization, global QCD PDFs analyses, and phenomenological applications of PDFs in the LHC era
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