Measurement of the t Distribution in Diffractive Photoproduction at HERA

TL;DR

This study measures the t distribution in diffractive photoproduction at HERA, revealing an exponential decay with a specific slope parameter, enhancing understanding of diffraction processes in photon-proton interactions.

Contribution

It provides the first measurement of the t distribution in diffractive photoproduction at HERA using the ZEUS detector, with detailed slope parameter determination.

Findings

t distribution is exponential in the studied range

Slope parameter b = 6.8 ± 0.9 (stat) +1.2/-1.1 (syst) GeV^{-2}

Results improve understanding of diffraction in photon-proton interactions

Abstract

Photon diffractive dissociation, $\gamma p \to Xp$, has been studied at HERA with the ZEUS detector using $ep$ interactions where the virtuality $Q^2$ of the exchanged photon is smaller than 0.02 GeV$^2$. The squared four-momentum $t$ exchanged at the proton vertex was determined in the range $0.073<|t|<0.40$ GeV$^2$ by measuring the scattered proton in the ZEUS Leading Proton Spectrometer. In the photon-proton centre-of-mass energy interval $176<W<225$ GeV and for masses of the dissociated photon system $4<M_X<32$ GeV, the $t$ distribution has an exponential shape, $dN/d|t| \propto \exp{(-b|t|)}$, with a slope parameter $b=6.8 \pm 0.9$~(stat.)~$ ^{+1.2}_{-1.1}$~(syst.)~GeV$^{-2}$.