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\begin{document}
       
\vspace*{2cm}
\begin{center} 
 {\large \bf Measurement of Prompt Photon Production with associated Jets} 

\vspace*{2cm}
 {\large \bf Abstract}
\end{center}

\vspace*{1cm}

    Results are presented on the photo-production of prompt photons and
    associated jets in the $\gamma p$ center of mass energy range
    $142 < W < 266$ GeV and $Q^2 < 1$ GeV$^2$.
     The data were taken at HERA in the years 1996-2000
    corresponding to an integrated luminosity of 105 pb$^{-1}$.
    Cross sections are given for photons in the $E_T$ and pseudo rapidity 
    range 
    $5 < E_T^{\gamma} < 10$~GeV, $-1 < \eta^{\gamma} < 0.9$ with
    associated jets
    in the range  
    $E_T^{jet} > 4.5$ GeV, $-1 < \eta^{jet} < 2.3$
    as a function of
    $E_T^{\gamma}, \eta^{\gamma}, E_T^{jet}, \eta^{jet}, x_{\gamma}$, and
    $x_p$, where
 $x_{\gamma}=(E_T^{jet}e^{-\eta^{jet}}+ E_T^{\gamma}e^{-\eta^{\gamma}})/2yE_e$
 and  $x^{p} = (E_T^{jet}e^{\eta^{jet}}+ E_T^{\gamma}e^{\eta^{\gamma}})/2E_p$
  correspond to
  the energy fractions of the
 exchanged photon and proton, respectively, participating in the hard process. 
    The photon is required to be isolated. The transverse energy
    in a cone in ($\eta,\phi$) of radius~1
    around the photon $E_T^{cone}$ is required not to exceed
    $0.1 \cdot E_T^{\gamma}$.
    The results are reasonably well described by pQCD calculations
in next to leading order.
    by M. Fontannaz, J.P. Guillet and G. Heinrich,
  Eur. Phys. J. C21 (2001) 303. 

    This analysis is an extension of an inclusive prompt photon analysis
    presented at ICHEP2002
    (http://www-h1.desy.de/h1/www/publications/htmlsplit/H1prelim-02-152.long.html).
       
\newpage

%  \begin{figure}[ht]
% \begin{center}
%\epsfig{file=H1prelim-03-035.fig1.eps,width=16cm,clip=}
%  \end{center}
%  \caption{
%  Distributions of the mean transverse shower radius (a),
%   the hot core fraction (b), and the energy fraction in the first
%   calorimetric layer (c) 
% for the selected photon candidates
%   (solid lines) summing over the full range
%   for $ -1 < \eta < 0.9, \; 5 < E_T^{\gamma} < 10$ GeV.
%     The simulated distributions for photons (dashed lines) and
%     background ($\pi^0 + \eta$, dotted lines)
%    are normalised by the likelihood fits of the signal extraction.
%}
%  \label{varfit}
%\end{figure}


\clearpage

\begin{figure}[ht] \unitlength 1pt
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   \put(-80,20){\epsfig{file=H1prelim-03-035.fig1.eps,width=350pt}}
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\caption{
Prompt photon differential cross sections with jet requirement
 as function of
$E_T^{\gamma}$, $\eta^{\gamma}$, $E_T^{jet}$, $\eta^{jet}$, $x_{\gamma}$,
 and $x_p$.
The data are compared with pQCD in LO (dashed line) and NLO.
 The error bands show the 
 effect of a variation of the renormalisation and factorisation scales
  in the NLO calculation from $0.5 \cdot E_T^{\gamma}$
 to $2 \cdot E_T^{\gamma}$. Also shown is the NLO result 
 corrected by PYTHIA for
  multiple interaction effects (dotted line).
}
 \label {NLOscale}
\end{center}
\end{figure}

\clearpage

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   \put(-90,0){\epsfig{file=H1prelim-03-035.fig2.eps,width=300pt}}
 \end{picture}
\caption{
Prompt photon differential cross sections with jet requirement
 as function of
$E_T^{\gamma}$ for symmetric cuts
 $E_{T,min}^{jet} = E_{T,min}^{\gamma} = 5$ GeV.
The data are compared with pQCD LO (dashed line) and NLO (solid line).
}
 \label {sym}
\end{center}
\end{figure}

\end{document}        
