Properties of hadronic final states in diffractive deep inelastic ep scattering at HERA

TL;DR

This study analyzes the properties of hadronic final states in diffractive deep inelastic scattering at HERA, revealing how the final state characteristics evolve with invariant mass and comparing results with Monte Carlo models.

Contribution

It provides detailed measurements of hadronic final state properties in diffractive DIS and compares them with model predictions, highlighting the dominance of qqg states.

Findings

Final state becomes more collimated and asymmetric with increasing invariant mass.

Hadronic final state properties are consistent with qqg parton-level states.

Results support specific Monte Carlo models for diffractive scattering.

Abstract

Characteristics of the hadronic final state of diffractive deep inelastic scattering events, ep -> eXp, were studied in the kinematic range 4 < M_X < 35 GeV, 4 < Q^2 < 150 GeV^2, 70 < W < 250 GeV and 0.0003 < x_pom < 0.03 with the ZEUS detector at HERA using an integrated luminosity of 13.8 pb^{-1}. The events were tagged by identifying the diffractively scattered proton using the leading proton spectrometer. The properties of the hadronic final state, X, were studied in its center-of-mass frame using thrust, thrust angle, sphericity, energy flow, transverse energy flow and ``seagull'' distributions. As the invariant mass of the system increases, the final state becomes more collimated, more aligned and more asymmetric in the average transverse momentum with respect to the direction of the virtual photon. Comparisons of the properties of the hadronic final state with predictions from various Monte Carlo model generators suggest that the final state is dominated by qqg states at the parton level.