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\begin{titlepage}
\noindent

\begin{center}
%{\it {\large version of \today}} \\[.3em]
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%Submitted to & \multicolumn{3}{r}{\footnotesize Electronic Access: {\it http://www-h1.desy.de/h1/www/publications/conf/conf\_list.html}} \\[.2em] \hline
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\multicolumn{4}{l}{{\bf
                XXII International Symposium on Lepton-Photon Interactions at High Energy},
                June~30,~2005,~Uppsala} \\
                 & Abstract:        & {\bf 401}    &\\
                 & Sessions: & {\bf Flavor physics} and {\bf QCD and hadron structure}   &\\ \hline
 & \multicolumn{3}{r}{\footnotesize {\it
    www-h1.desy.de/h1/www/publications/conf/conf\_list.html}} \\[.2em]
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\vspace*{2cm}

\begin{center}
  \Large
  {\bf
Acceptance corrected ratios of $D^*p(3100)$ and $D^*$ yields and differential 
cross sections of $D^*p(3100)$ production}
\vspace*{1cm}
    {\Large H1 Collaboration}
\end{center}


\begin{abstract}

The measurement of acceptance corrected ratios 
$\sigma(D^*p(3100))/\sigma(D^*)$ 
for electro-production of the anti-charmed baryon state $D^*p(3100)$ 
decaying into 
$D^*$ and $p$ is presented. The analysis based on the 1996-2000 
data is performed in the deep inelastic scattering region 
$1<Q^2<100$ GeV$^2$, $0.05<y_e<0.7$.

\end{abstract}

\end{titlepage}

\section{Introduction}

Motivated by recent experimental evidence for the production
of a strange pentaquark $\Theta^+$ in various reaction processes
\cite{thetaKn,thetaKp,zeusspq} the H1 experiment performed a
search for a charmed pentaquark decaying to $D^{*-}p$~\footnote{
The charge conjugate state is always implied if not otherwise stated 
explicitly.}
in inelastic electron-proton collisions
at centre-of-mass energies of 300~GeV and 320~GeV at HERA. 
A narrow resonance at a mass of $3099$~MeV was observed in this 
decay channel \cite{h1cpq}.
Subsequent $\Theta_c$ searches by other high energy physics experiments did
not confirm this observation \cite{alephcpq,cdfcpq,focuscpq,bellecpq,zeuscpq}.

It is difficult to draw conclusions from the apparently contradicting 
situation of observations and non-observations of pentaquarks in different
high energy processes due to lack of understanding of its
possible production mechanism. 
In order to facilitate further comparisons of experimental results and to 
investigate the production mechanism of the $D^*p(3100)$ resonance\footnote{
Since the spin of the resonance is unknown the term $D^*p(3100)$ is used 
through out this paper although it is a candidate for the $\Theta_C$.}, its production phase space is 
explored in this paper. The data presented here include
acceptance corrections
based on a simple model assuming pentaquark production as part of the
fragmentation process as suggested by the high energy pentaquark 
observations  \cite{zeusspq,h1cpq}. Preliminary results on
the acceptance corrected total yields ratio
$R_{cor}(D^*p(3100)/D^*)$ in the visible $D^*p$ and $D^*$ range,
differential distributions of the acceptance corrected cross section ratio
$\sigma(D^*p(3100))/\sigma(D^*)$ as function of variables related to the 
event kinematics and the $D^*$ meson and 
differential cross sections for $D^*p(3100)$ production are given. 
   
\section{Experimental Procedure}
\label{method}
\subsection{H1 Apparatus}
\label{detector}
The tracks from charged particles 
used in this analysis are reconstructed in the H1
central tracker, whose main components are two cylindrical drift chambers,
the inner and outer central jet chambers (CJCs), 
covering the polar angle region $20^\circ < \theta < 160^\circ$. 
The H1 experiment uses a coordinate system in
which the positive $z$-axis is defined by the direction of the outgoing
proton beam. The polar angle $\theta$ of a particle is defined relative
to this axis and is related to
the pseudorapidity $\eta$ by $\eta = - \ln \tan \theta / 2$.
The inner and outer CJCs are mounted concentrically around the beam-line,
have $24$ and $32$ sense wires, respectively, 
and cover radii between $20 \ {\rm cm}$ and $84 \ {\rm cm}$.
The information from the CJC sense wires is digitized using $100 \ {\rm MHz}$
FADCs, providing simultaneous charge and timing measurements. 
The CJCs lie within a homogeneous magnetic field of 
$1.15 \ {\rm T}$, which allows measurements of 
the transverse momenta of charged particles.
Two additional drift chambers complement
the CJCs by precisely
measuring the $z$ coordinates of track segments and hence assist in the
determination of the particle's polar angle. 
The Central Silicon Tracker, consisting of two layers at radii of
$6 \ {\rm cm}$ and $10 \ {\rm cm}$, is also used to improve 
the charged particle track and event vertex reconstruction.
The transverse momentum resolution of the central tracker is
$\sigma(\pt) / \pt \simeq 0.005 \ \pt \ [{\rm GeV}] \ \oplus 0.015$.
The charge misidentification probability is 
negligible
for particles originating from the primary vertex which have transverse momenta
in the range relevant to this analysis. 

The specific ionization energy loss of charged particles is derived 
from the mean of the inverse square-root
of the charge collected by all CJC sense wires with a signal above
threshold. The resolution is
$\sigma(\dedxf) / (\dedxf) \simeq 8 \%$ on average 
for minimum ionizing particles \cite{steinhart}.

A lead/scintillating-fibre spaghetti calorimeter (SpaCal) 
is located in the direction of the outgoing 
electron beam.
It contains both electromagnetic and hadronic sections and
is used to detect the scattered electron in DIS events.
The global properties of the hadronic final state are reconstructed 
using an algorithm which takes information from the
central tracker, the SpaCal, and also from a Liquid Argon  
calorimeter, which surrounds the central tracker. 
The deep inelastic scattering (DIS) events studied in this paper are triggered 
on the basis of  a scattered electron in the SpaCal, complemented by the
signals in the CJCs and multi-wire proportional chambers in the 
central tracker. Further details of the H1 detector can be 
found in \cite{h1det}. 

\subsection{Event Sample}

The analysis is carried out using data taken in the years
1996-2000, when HERA collided 
electrons\footnote{The analysis uses data from periods when
the beam lepton was either a positron ($88 \%$ of the total) or an electron 
($12 \%$ of the total).}  
of energy $27.6 \ {\rm GeV}$ with protons at 
$820 \ {\rm GeV}$ (1996-1997) and $920 \ {\rm GeV}$ (1998-2000).
The integrated luminosity of the sample is $76 \ {\rm pb^{-1}}$.

The scattered electron energy, measured in the SpaCal, 
is required to be above $8 \ {\rm GeV}$, and 
the virtuality of the exchanged 
photon\footnote{The inclusive DIS kinematic variables are defined as
$Q^2 = - q^2$, $y = q \cdot p \, / \, k \cdot p$ and
$x = -q^2 \, / \, 2 q \cdot p$, where $q$, $k$ and $p$
are the 4-vectors of the exchanged photon, the incident electron and
the incident proton, respectively.} 
is required to lie in the range $1 < Q^2 < 100 \ {\rm GeV^2}$, as
reconstructed from the energy and polar angle of the 
electron. 
To ensure that the hadronic final state lies in the region well covered
by the central trackers, the inelasticity of the event 
is required to satisfy $0.05 < y < 0.7$,
calculated from the scattered electron kinemaitics. 
The $z$ coordinate of the event vertex, reconstructed using the 
central tracker, is required to lie within $35 \ {\rm cm}$ 
of the mean position for $ep$ interactions. 
The difference between the total
energy $E$ and the longitudinal component of the total
momentum $p_z$, calculated 
from the electron and the hadronic final state, is restricted
to $35 \ {\rm GeV} < E - p_z < 70 \ {\rm GeV}$. This requirement suppresses  
photoproduction background, where a hadron
fakes the electron signature.

\subsection{Selection of {\boldmath $D^*$} Meson and Proton Candidates}
\label{dsprec}

%Details of 
The selection of $D^*$ mesons and proton candidates is the same as in 
\cite{h1cpq} with further details given in 
\cite{f2c}. Therefore only a brief summary is given here:
\begin{itemize}   
\item The decay channel $D^* \rightarrow D^0 \pi_s \rightarrow K \pi \pi_s$
is used to reconstruct $D^*$ mesons.
\item $D^*$ candidates are required to have:
\begin{itemize} 
\item a minimum transverse momentum in the laboratory frame of
$\pt(D^*) > 1.5 \ {\rm GeV}$,
\item  a pseudorapidity $\eta=-\log\tan(\Theta/2)$~in the laboratory frame 
in the range $-1.5 < \eta(D^*) < 1$ and
\item a minimum inelasticity $z(D^*) = (E - p_z)_{D^*} / 2 y E_e$ of
$z(D^*) > 0.2$, which account for the hard fragmentation of charmed hadrons. 
 
\end{itemize}
In this kinematic region the combinatorial background to the $D^*$ signal 
is small. 

Some of the measured differential cross sections, namely the inelasticity
distribution and the fragmentation function of 
the $D^*p(3100)$ baryon and the $D^*$ meson from
$D^*p(3100)$ decay, are strongly affected by the cut in $z(D^*)$.
In order to obtain reasonable acceptances in the full variable range for these
quantities the cut in $z(D^*)$ is replaced by a cut in the $D^*p(3100)$
fragmentation variable
\footnote{The measurement of the fragmentation function $x_{obs}$ is
studied in section \ref{fragm}.
} $x_{obs}(D^*p)$
%The measurement of the inelasticity distribution of the $D^*$ meson
%and especially of the  $D^*p(3100)$ baryon is strongly affected by the
%In inclusive $D^*$ meson production the inelasticity 
%$z(D^*)$ is a  convolution of the inelasticity $z(c)$ of the parent charm 
%quark and fragmentation function
%\footnote{The measurement of the fragmentation function $x_{obs}(D^*)$ is
%studied in section \ref{fragm}.} $x_{obs}(D^*)$ 
which is the momentum fraction
of the charm quark carried by the $D^*p(3100)$ baryon by the following 
requirement
\begin{itemize}
\item  $x_{obs}(D^*p)>min(0.5\cdot p(p),0.5)$, where
$p(p)$ is the momentum of the proton. This selection cut  
allows to access the low $x_{obs}$ and $z$ regions
with reasonable efficiency and gives
the best sensitivity according to the pentaquark Monte Carlo and the 
non charm induced background as obtained from the data.
\end{itemize}
%In total $4219\pm 86$
%$D^*$ mesons are observed in the distribution of the mass difference
\item $D^*$ candidates having a mass difference 
$\Delta M_{D^*} = m (K \pi \pi_s) -  m (K \pi)$
within $\pm2.5~\rm{MeV}$ of the nominal value
%\item $D^*$ candidates lying within $\pm2.5~\rm{MeV}$ of
%the nominal value of 
$\Delta M_{D^*} = 145.4 ~\rm{MeV}$ are combined with oppositely charged
proton candidates selected according to the proton likelihood based on the
particles energy loss \dedx in the central trackers. The invariant mass
distribution $M(D^* p) = m(K \pi \pi_s p) - m(K \pi \pi_s) + m(D^*)$ of these
combinations is shown in figure~\ref{signal} \cite{h1cpq}. 
\end{itemize}

\subsection{Monte Carlo Simulation}
\label{model}
Monte Carlo simulation is used to determine acceptances for the $D^*$ meson
and for the $D^*p(3100)$ baryon. The acceptances were calculated 
using the RAPGAP 3.1 \cite{rapgap}
event generator incorporating fragmentation according to the
Lund string model \cite{lund} implemented in PYTHIA 6.1 \cite{pythia}.

For simulation of the $D^*p(3100)$ baryon 
it is assumed that pentaquarks are produced by fragmentation
as suggested by the observation of the $D^*p(3100)$ resonance \cite{h1cpq}
in high energy $ep$ scattering.
The decay of the $D^*p(3100)$ was introduced by changing
the properties of the $D_1(2420)$ and $D_2^*(2460)$ such that they decay to
$D^*$ meson plus proton with a natural width of zero, a mass of 3100 MeV
and assuming isotropic decay. This model will be subsequently refered to as 
fragmentation production model. 

The generated events are passed through the full detector simulation using
GEANT 3.15 \cite{geant} and are subsequently subjected to the same 
reconstruction and analysis chain as the data.

\section{Results}
\subsection{Total acceptance corrected \boldmath{$ D^*p(3100)/D^*$} yields ratios}

The observed yields ratio $R(D^*p(3100)/D^*)=(1.46\pm0.32)\%$ has been corrected for 
$D^*p(3100)$ and $D^*$ acceptances with the approach described in the 
previous section. Because of our lack of knowledge about the 
$D^*p(3100)$ production mechanism and the ignorance of
the angular momenta involved in its decay.
The total acceptance corrected yields 
ratio is given for the visible range of the 
$D^*p(3100)$:
$p_t(D^*p(3100))>1.5$ GeV, $-1.5<\eta(D^*p(3100))<1.0$ 
and of the $D^*$ meson:
$p_t(D^*)>1.5$ GeV, $-1.5<\eta(D^*)<$1.0, $z(D^*)>$0.2. 
The same $D^*$ visibility requirements are applied to the $D^*$ meson
originating from $D^*p(3100)$ baryon decay.

%When applying the acceptance corrections to the  $D^*p(3100)$ baryon 
%Wno extrapolation to the full decay phase space is done for the  $D^*$ mesons
%Woriginating from the $D^*p(3100)$ decay such that these $D^*$ mesons have 
%Walso to fulfill the requirements for the $D^*$ selection above. 
For this visible range the total acceptance 
corrected yields ratio is
\begin{equation}
R_{cor}(D^*p(3100)/D^*)=\left(1.59 ~\pm ~0.33(stat.)^{+~0.33}_{-~0.45}(syst.)
\right)~\%.
\label{rcor}
\end{equation}
The systematic error includes the following sources 
of uncertainties: %(relative change of $R_{cor}$):
\begin{itemize}
\item the dependence  on the 
background shape used in the fit to the data shown in fig.\ref{signal},
\item the dependence on the
$D^*$ selection window in the $\Delta M_{D^*}$ distribution,
%\item a change of -9\% when reducing the $D^*$ selection window in the
%$\Delta M_{D^*}$ distribution from 2.5~MeV to 1.5~MeV,
%\item a change of -12\% events from the 
%the choice of the background shape in fig.\ref{signal},
\item the variation due to a cut of $z(D^*)>0.1$,
\item the effect of removing possible contributions
from $D_1(2420)$ and $D_2^*(2460)$~due to pions misidentified as protons
by requiring $|M(D^*\pi)-2450~\rm{MeV}|~>~50$~MeV,
\item uncertainties in the \dedx proton selection efficiency ,
\item the effect of a softer  
fragmentation function of the  $D^*p(3100)$ baryon,
\item the variation of the $D^*p(3100)$ efficiency due to reweighting the
$\eta(D^*p)$ distribution to better describe the observed distribution 
in fig.\ref{dsp}a (see below).
%\item efficiency variations due to re-weighting of the $D^*p(3100)$ 
%decay angle distribution.  
\end{itemize}
The different contributions to the systematic error are summarized in 
table \ref{syst1}. The largest positive contribution to the systematic error 
on $R_{cor}$ is obtained when the $D_1(2420)$ and $D_2^*(2460)$ veto cut 
is applied in the $D^*p$ selection. The largest
negative variation is observed
when the cut against combinatorial background is reduced from  $z(D^*)>0.2$
to $z(D^*)>0.1$.

The acceptance corrected ratio $R_{cor}$ in the visible range (eq. \ref{rcor})
can be compared
with the 95\% C.L. upper limit of $R_{cor}<0.51\%$ obtained by the ZEUS
experiment in deep inelastic $ep$ scattering \cite{zeuscpq} using a  
 different definition of the visible range. 
%To suppress the non-charm induced
%background both analyses use a minimum requirement on observables 
%which are motivated by the hard
%fragmentation of charmed hadrons. However, there is a substantial difference
%in the choice of these observables. While the inelasticity $z(D^*)$, used for 
%background suppression in the analysis presented here, is a convolution of the
%charm quark energy and the fragmentation/hadronization value of the 
%$D^*$ meson, the quantity $p_t(D^*)/\sum^{\Theta>10^o}$, used in the
%ZEUS analysis, depends only
%on the  fragmentation/hadronization value of the 
%$D^*$ meson. Since $D^*$ mesons originating from $D^*p(3100)$ decay have to be
%significantly softer than $D^*$ mesons directly produced in the fragmentation
%of charm quarks
%for simple decay kinematic reasons these cuts may act 
%differently on a possible $D^*p(3100)$ signal. Furthermore due to the physics
%of charm production the two cuts suppress different regions in pseudorapidity
%of the produced $D^*$ meson in the laboratory frame as well as in the 
%hadronic centre-of-mass system. In the laboratory frame the average $z(D^*)$
%is larger for $\eta(D^*)<0$ 
%while the mean of $p_t(D^*)/\sum^{\Theta>10^o}$ tends to be
%smaller here because the hadronic final state is more completely  
%measured in the detector.

%\Blue
%{The 90\% C.L. upper limit from the BELLE experiment \cite{bellecpq} of 
%$Br(B^0\rightarrow\Theta_c\overline{p}\pi)
%\times Br( \Theta_c\rightarrow D^{*-}p)
%/Br(B^0\rightarrow D^{*-}p\overline{p}\pi)<11\%
%$ shows that the analysis of exclusive $B^0$ decay 
%has not reached the sensitivity
%obtained by the analysis presented here.} 

If acceptance corrections
to the  $D^*p(3100)$ signal are applied by extrapolating 
to the full $D^*$ phase space from $D^*p(3100)$ decay based on 
the fragmentation production model
%the model assumption for pentaquark production given in section \ref{model},
%i.e. the visibility range
%for the $D^*p(3100)$ sample does not include any $D^*$ visibility requirements
a visible cross section ratio of
\begin{equation}
\sigma_{vis}(D^*p(3100))/ \sigma_{vis}(D^*)=
\left(2.48 \pm 0.52(stat.)^{+0.85}_{-0.64}(syst.)\right)~\%
\end{equation}
is obtained. 
The contribution to the systematic uncertainties 
on this ratio are given in
table \ref{syst2}. Due to the extrapolation to the full $D^*$ meson phase space
in the $D^*p(3100)$ decay the largest positive variation of the ratio is 
observed when a softer fragmentation model has been used for the $D^*p(3100)$
baryon. Large negative variations are obtained when replacing the 
background suppression cut in the inelasticity $z$ of the $D^*$ meson by the
cut in the fragmentation value of the $D^*p(3100)$ baryon,
as described in section \ref{dsprec},
 or when using the 
shape of the background model in figure \ref{signal} for the fit of the 
$D^*p$ mass distribution.

\subsection{Differential distributions in 
\boldmath{$\sigma_{vis}(D^*p(3100))/ \sigma_{vis}(D^*)$}}
\label{sigds}
In order to explore the properties of the events contributing to the 
$D^*p(3100)$ signal, acceptance corrected ratios 
$\sigma_{vis}(D^*p(3100))/ \sigma_{vis}(D^*)$ have been determined from   
$M(D^* p)$ mass distributions in bins of a variety of phase space variables.
In this section distributions related to event kinematics and to properties 
of the $D^*$ mesons involved in the $D^*p(3100)$ decay are studied. 
%Due to the small $D^*p(3100)$ data sample available in this analysis 
%the number of $D^*p(3100)$ events is determined from a background plus signal 
%fit to the $D^*p$ mass distributions with fixing the signal mass and width to
%$M(D^*p(3100))=3099$~MeV and $\sigma=12$~MeV \cite{h1cpq}, respectively. 
%For the same reason 
For this preliminary analysis only statistical errors will be shown. 

%In this section the properties of the events contributing to the 
%$(D^*p(3100)$ signal is explored 
In figure \ref{kine} the acceptance corrected ratio 
$\sigma_{vis}(D^*p(3100))/ \sigma_{vis}(D^*)$ is shown as a function of the hadronic mass 
$W$, the four momentum transfer squared of the virtual photon $Q^2$, and
the invariant mass of the $c\overline{c}$ system, $\hat{s}_{obs}$. In 
leading order
the invariant mass $\hat{s}_{obs}$ is given by
\begin{equation}
\hat{s}_{obs}=\frac{\displaystyle p_t^{*2}(c)+m_c^2}
{\displaystyle z(c)(1-z(c))},
\label{shat}
\end{equation}
where $p_t^*(c)$ and $z(c)$ denote the transverse momentum 
in the photon-gluon system and the inelasticity of the charm quark,
respectively. 
Since the quantities related to the charm quark are not accessible the 
invariant mass $\hat{s}_{obs}$ has to be reconstructed from the charmed 
hadrons instead.
The expression \ref{shat} can be 
rewritten as
%from the $D^*p(3100)$ and $D^*$ properties, respectively, 
%according to
\begin{equation}
\hat{s}_{obs}=\frac{\displaystyle p_t^{*2}/x_{obs}+m_c^2x_{obs}}
{\displaystyle z(1-z/x_{obs})},
\end{equation}
with the transverse momentum $p_t^*$ in the centre-of-mass system, 
the fragmentation value $x_{obs}$
%, which measures the momentum fraction of the
%charm quark carried by the charmed hadron,
%\footnote{The fragmentation is studied in section \ref{fragm}.} 
and the inelasticity $z$ of the $D^*p(3100)$ and $D^*$, respectively.

Figure \ref{kine} also includes the expectation for 
$\sigma_{vis}(D^*p(3100))/ \sigma_{vis}(D^*)$ using the fragmentation 
production model. 
Since the absolute normalization of the $D^*p(3100)$ rate is not fixed in
the model, the $D^*p(3100)$ yield is normalized such to reproduce
the ratio $R_{cor}$ in (\ref{rcor}). 
The expected variation of the ratio with $W$ and $\hat{s}_{obs}$ is a 
consequence of threshold effects due to the significantly different masses 
of the $D^*p(3100)$ and $D^*$. The 
observed dependence on $W$ and on $Q^2$ is well described by this model, while
it is significantly above the data at large $\hat{s}_{obs}$. 
%\Blue{As can be 
%inferred from the errors the $D^*p(3100)$ signal is most pronounced for 
%$\hat{s}_{obs}>100~\gev^2$ while for $\hat{s}_{obs}<30~\gev^2$ the observed 
%$D^*p(3100)$ mass distribution is consistent with background only. 
%The FOCUS experiment which has preliminarily reported a negative result
%of a $\Theta_c$ search \cite{focuscpq}  
%is sensitive to the low
%$\hat{s}$ region only \cite{focus}.}

In order to investigate the properties of the $D^*$ mesons contributing
to the $D^*p(3100)$ resonance 
the ratio $\sigma_{vis}(D^*p(3100))/ \sigma_{vis}(D^*)$ is shown in figure \ref{dstar}
as a function of the pseudorapidity $\eta(D^*)$ and the transverse momentum 
$p_t(D^*)$, both in the laboratory frame, the inelasticity
$z(D^*)$ and the pseudorapidity $\eta^*(D^*)$ in the hadronic
centre-of-mass system. Also shown are the expectations from the model.
 
The most striking feature in the data is the suppression of the $D^*p(3100)$ 
baryon relative to $D^*$ meson production
in the near to central region both in the laboratory frame and in the 
hadronic centre-of-mass system. Such a dependence is not predicted by the 
fragmentation production model.
 The data indicate that $D^*p(3100)$ baryon production is closer 
to the photon direction than normal $D^*$ meson production. 
%In terms of 
%pseudorapidities the cleanest
%$D^*p(3100)$ signal-to-background ratio is observed in the very backward 
%$\eta(D^*)$ bin in the laboratory frame and closer to the 
%  photon direction in the hadronic
%centre-of-mass system, respectively, while in the close to central 
%rapidity regions the signal becomes marginal. \Blue{The main source for charm 
%production at HERA is the photon-gluon fusion process which is 
%similar to the gluon-gluon fusion process
%at the Tevatron. 
%Preliminary result on the non-observation of pentaquarks at Tevatron 
%have been reported by the CDF collaboration \cite{cdfcpq}. 
%In contrast to the HERA experiments the experiments at Tevatron 
%are mainly sensitive to the central rapidity region
%in the hadronic centre-of-mass system.}
% while the experiments at HERA are more sensitive towardsto the
%HERA experiments.
% due to the symmetric machine. 
%in which the CDF analysis is performed \cite{cdfcpq}. 
Figure \ref{dstar} also shows the ratio $\sigma_{vis}(D^*p(3100))/ \sigma_{vis}(D^*)$
as a function of the inelasticity $z(D^*)$. The
$D^*p(3100)$ baryons contribute mainly at
small $z(D^*)$ as expected from the masses of the particles involved in the
$D^*p(3100)$ decay\footnote{In order to access the small $z(D^*)$ region
the cut in this variable is replaced by a minimum requirement in 
the $D^*p(3100)$
fragmentation variable given in section \ref{dsprec}.} within the framework
of the fragmentation production model. 
%Assuming boson-gluon fusion to be responsible
%also for charmed pentaquark production the $z(D^*)$ distribution 
%observed in $D^*p(3100)$
%decay is an indication for a soft hadronization function of $D^*$ mesons
%originating from $D^*p(3100)$. The hadronization function is studied in detail
%in section \ref{fragm}.


\subsection{Differential \boldmath{$D^*p(3100)$} cross sections }

To get information of the $D^*p(3100)$ production mechanism 
$D^*p(3100)$ differential cross sections in $D^*p(3100)$ quantities
 are presented in this section. The fragmentation production model 
is used for acceptance corrections. As in the previous section
only statistical errors are given in the figures.

In figure \ref{dsp} the differential $D^*p(3100)$ production cross section
is shown as a function of the pseudorapidity $\eta(D^*p)$ 
and the transverse momentum $p_t(D^*p)$, both in the laboratory frame, 
the inelasticity $z(D^*p)$ and the pseudorapidity $\eta^*(D^*p)$ 
in the hadronic centre-of-mass system. 
The $D^*p(3100)$ production cross section shows the same features as a 
function of the pseudorapidities $\eta(D^*p)$ and $\eta^*(D^*p)$ than observed
for the ratio $\sigma_{vis}(D^*p(3100))/ \sigma_{vis}(D^*)$ 
as a function of the $D^*$ variables. Within the quite large statistical 
errors the shapes of the $z(D^*p)$ and of the $p_t(D^*p)$ distributions
are consistent with the fragmentation production model.
%those of the $z(D^*)$ and $p_t(D^*)$ cross sections
%of inclusive $D^*$ meson production as given in ref. \cite{f2c}. 
These two 
distributions are suggesting that boson gluon fusion is the source for
the production of $D^*p(3100)$ baryons while the pseudorapidity distributions
are not evidently supporting this picture.

\subsection{Fragmentation function}
\label{fragm}
For the comparison of the observation of the $D^*p(3100)$ resonance in deep
inelastic $ep$ scattering by H1 with results obtained in other high energy 
physics processes the momentum fraction from the parent charm quark 
carried by the $D^*p(3100)$ and the $D^*$ from $D^*p(3100)$ decay is of 
specific interest.

%In contrast to charm production in $e^+e^-$ annihilation  
%where in leading order QCD the charm quarks are created back-to-back in the 
%laboratory frame and their energies are given 
%by the beam energies the
%situation is not so simple in $ep$ scattering. Here the charm quarks are not
% back-to-back in the laboratory frame and their
%energies have to be reconstructed from the observed final state. Since in
%$ep$ scattering charm quarks are mainly produced at threshold, i.e.
%$\hat{s}\approx 4m_c^2$, jet methods
%are not the primary choice for the reconstruction of the charm quarks
%because one has to require a certain minimum transverse momentum $p_t$
%of some GeV.This cut  
%allows to access the low $x_{obs}(D^*p)$ region
%with reasonable efficiency and gives
%the best sensitivity according to the pentaquark Monte Carlo and the 
%non charm induced background as obtained from the data.
%In this way charm quarks could only be reconstructed reliably at 
%$\hat{s}\approx 4p_t^2+ 4m_c^2$, significantly above 
%the charm production threshold. 

In order to measure the $D^*p(3100)$ fragmentation function and the $D^*$ 
hadronization function for $D^*$ mesons from $D^*p(3100)$ decay the analysis
is performed in the hadronic centre-of-mass system. The method 
used to reconstruct the fragmentation variable $x_{obs}$ is sketched
in figure \ref{fmethod}. It is similar to the method presented in reference
\cite{rxobs}. In the plane 
perpendicular to the photon direction in this frame the charm quarks from the
leading order boson gluon fusion process exhibit a back-to-back signature
similar to the situation in  $e^+e^-$ annihilation. In this way it becomes
possible to reconstruct the visible quark energy even close to threshold from 
the hadronic final state. For the analysis only those particles with 
$\eta^*>0$ are used which belong to the photon hemisphere 
(fig. \ref{fmethod}a).
Those particles which have angle smaller than $\pi/2$ with respect to the
$D^*$ direction in the projection plane perpendicular to the photon direction
are subsequently assigned to the  $D^*$ hemisphere. 
The $D^*p(3100)$ fragmentation variable and the
$D^*$ hadronization variable can then be defined as
\begin{equation}
x_{obs}=\frac{\displaystyle (E-p_z)}{\displaystyle \sum_{h\in hemi}(E-p_z)_h},
\end{equation} 
where $(E-p_z)$ denotes the value of $E-p_z$ of the hadrons  
in the laboratory frame.
In the enumerator enter the quantities of the $D^*p(3100)$ baryon
or the $D^*$ meson, respectively, while the sum in the denominator runs 
over all hadrons attributed to the $D^*$ hemisphere in the plane perpendicular
to the photon direction. This method yields a definition of the fragmentation
function similar to what is used in $e^+e^-$ annihilation.

In figure \ref{xobs} the acceptance corrected cross section ratio 
$\sigma_{vis}(D^*p(3100))/ \sigma_{vis}(D^*)$ as a function of the  
$D^*$ hadronization value $x_{obs}(D^*)$ and the differential $D^*p(3100)$
cross section as a function of $x_{obs}(D^*p)$
are shown together with the prediction
from the model. 
%In order to access the full range of the fragmentation/hadronization
% variable, the selection
%cut $z(D^*)>0.2$ was replaced by $x_{obs}(D^*p)>min(0.5\cdot p(p),0.5)$, where
%$p(p)$ is the momentum of the proton. This cut  
%allows to access the low $x_{obs}(D^*p)$ region
%with reasonable efficiency and gives
%the best sensitivity according to the pentaquark Monte Carlo and the 
%non charm induced background as obtained from the data. 
The ratio $\sigma_{vis}(D^*p(3100))/ \sigma_{vis}(D^*)$ increases with 
decreasing $x_{obs}(D^*)$ value which means that $D^*$ mesons originating from
$D^*p(3100)$ decay are significantly softer than inclusive $D^*$ mesons which
carry most of the charm quark energy. 
In case of inclusive measurements of $D^*$ meson production in deep inelastic
scattering at HERA
the most probable fragmentation value is  
$x_{obs}(D^*)\approx 0.7$  \cite{rxobs}.
%from $D^*$ mesons production is about 0.7 in the kinematic range
%explored in deep inelastic $ep$ scattering at HERA \cite{rxobs}. 
The significantly softer $x_{obs}(D^*)$ distribution of $D^*$ mesons 
contributing to the $D^*p(3100)$ resonance
is consistent with the expectation from the
decay of the $D^*p(3100)$ particle. 

%\Blue{The ALEPH experiment has reported a negative result from the $\Theta_c$ 
%search \cite{alephcpq}. According to the information given in reference 
%\cite{alephc} the $D^*$ selection used in the analysis prefers 
%those $D^*$ mesons carrying a substantial fraction of the charm quark energy
%both, for $e^+e^-\rightarrow c\overline{c}$ and  
%$e^+e^-\rightarrow b\overline{b}$ with the subsequent decay into charm.
%From QCD evolution one expects a softer $D^*$ fragmentation 
%function at $\sqrt{s}=M_z$
%compared to the one observed in deep inelastic $ep$ scattering at HERA
%\cite{rxobs}. Therefore the $D^*$ hadronization function
%for $D^*$ mesons coming from $D^*p(3100)$ decay is expected to be even softer
%at LEP compared to what is observed in  
%figure~\ref{xobs}a at HERA. The $D^*$ mesons from $D^*p(3100)$ decay should 
%have a hadronization function at LEP which comes close to what is expected 
%from gluon splitting, i.e. $g\rightarrow c\overline{c}$. It is not evident
%if the ALEPH analysis is sensitive to such soft $D^*$ mesons.}

In figure \ref{xobs}b
the differential
cross section $d\sigma_{vis}(D^*p(3100))/dx_{obs}(D^*p)$ is shown
as a function of $x_{obs}(D^*p)$. The $D^*p(3100)$
fragmentation function is very hard compared to the $D^*$ hadronization 
function
of figure~\ref{xobs}a. A hard fragmentation is 
expected for charmed hadrons. Within the limited 
statistics this differential cross section indicates a harder fragmentation 
function for the $D^*p(3100)$ baryon
compared to that observed in inclusive $D^*$ mesons production \cite{rxobs},
which is expected due to the larger $D^*p(3100)$ mass compared to
the $D^*$ mass. 
  
%\section{Discussion}

\section{Conclusions}
A detailed analysis of the exotic $D^*p(3100)$ baryon has been presented.
An acceptance corrected yields ratio
$ R_{cor}(D^*p(3100)/D^*)=
\left(1.59 ~\pm ~0.33(stat.)^{+~0.33}_{-~0.45}(syst.)\right)~\%$
for the visible $D^*p(3100)$ and $D^*$ range has been observed. In the case
of the $D^*p(3100)$ the visibility requirement is simultaneously imposed to 
the $D^*p(3100)$ as well as to its decay product, the $D^*$ meson. When 
extrapolating to the full phase space of the decay products one observes 
a ratio of the visible cross sections of
$\sigma_{vis}\left(D^*p(3100)\right)/ \sigma_{vis}(D^*)=
\left(2.48 \pm 0.52(stat.)^{+0.85}_{-0.64}(syst.)\right)~\%$.

Differential distributions of $\sigma_{vis}(D^*p(3100))/ \sigma_{vis}(D^*)$ as a function
of event kinematics and $D^*$ quantities have been presented. 
In general the fragmentation production model leads to a reasonable
description of the distributions with some  exceptions. The most 
striking deviation from the expectation is observed in $\eta(D^*)$ and 
$\eta^*(D^*)$. Compared to inclusive $D^*$ production the $D^*p(3100)$ 
production seems to be suppressed in the close to central rapidity regions
in both frames. The differential $D^*p(3100)$ cross sections as a function
of  $D^*p(3100)$ variables show the same effect. The
$D^*p(3100)$ fragmentation function is hard, consistent with the 
expectation for a charmed hadron with the given mass. The hadronization
function for $D^*$ mesons contributing to the $D^*p(3100)$ resonance is 
much softer than observed in inclusive $D^*$ mesons production. This 
observation is consistent with the expectation for a particle with a mass
of 3100 MeV decaying to  $D^*$ meson plus proton.
%%%          THE PAPER DRAFTS HAVE NO AUTHORLIST

%%%          FOR PAPER ISSUED FOR THE FINAL READING 
%%%          COPY THE AUTHOR AND INSTITUTE LISTS 
%%%          INTO YOUR AREA
%%% from /h1/iww/ipublications/h1auts.tex 
%%%          AND UNCOMMENT THE NEXT THREE LINES 
%%%\begin{flushleft}
%%%  \input{h1auts}
%%%\end{flushleft}
%%%%%%%%%%%%%%%%%%%% ratios: electron kinematics %%%%%%%%%%%%%%%%%%%%%
\begin{thebibliography}{99}

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\bibitem{thetaKn} %%
%LEPS Collaboration,
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%CLAS
S.~Stepanyan {\it et al.}, (CLAS), Phys. Atom. Nuclei {\bf 66} (2003) 1715;\\
%SAPHIR Collaboration,
J.~Barth {\it et al.}, (SAPHIR), Phys. Lett. B {\bf 572} (2003) 127;\\
%CLAS Collaboration,
V.~Kubarovsky {\it et al.}, (CLAS), Phys. Rev. Lett. {\bf 92} (2004) 03201 [erratum-ibid. 92 (2004) 049902].
\bibitem{thetaKp} %%
%DIANA Collaboration,
V.~V.~Barnim {\it et al.}, (DIANA), Phys. Atom. Nucl. {\bf 66} (2003) 1715 [Yad. Fiz. 66 (2003) 1763];\\
A.~E.~Asratyan, A.~G.~Dolgolenko and M.~A.~Kubantsev, Phys. Atom. Nucl. {\bf 67} (2004) 682;\\
%SVD COllaboration,
A.~Aleev {\it et al.}, (SVD), hep-ex/0401024;\\
%HERMES Collaboration,
A.~Airapetian {\it et al.}, (HERMES), Phys. Lett. B {\bf 585} (2004) 127;\\
%COSY-TOF Collaboration,
M.~Abdel-Bary {\it et al.}, (COSY-TOF),Phys. Lett. B {\bf 595} (2004) 127.
%ZEUS obs
\bibitem{zeusspq} S.~Chekanov {\it et al.} [ZEUS Collaboration],
Phys. Lett. {\bf 591} (2004) 7.
%
\bibitem{h1cpq} A.Aktas {\it et al.} [H1 Collaboration]
Phys. Lett {\bf B 588} (2004) 17.
%
%% non obs
\bibitem{zeuscpq} S.~Chekanov {\it et al.} [ZEUS Collaboration], Eur. Phys. J.
{\bf C 38} (2004) 29.
\bibitem{alephcpq} 
S.~R.~Armstrong, hep-ex/0410080; S.~Schael {\it et al.}, (ALPEH), Phys. Lett. B {\bf 599}(2004)  1.
\bibitem{cdfcpq}
D.~O.~Litvintsev, (CDF), hep-ex/0410024.
\bibitem{focuscpq}
K.~Stenson (FOCUS), hep-ex/0412021.
\bibitem{bellecpq}
R.~Mizuk {\it et al.}, (Belle), hep-ex/0411005.
%
\bibitem{steinhart} J. Steinhart, `Die Messung des totalen 
$c \bar{c}$-Photoproduktions-Wirkungsquerschnittes durch die
Rekonstruktion von $\Lambda_c$ Baryonen unter
Verwendung der verbesserten \dedx Teilchen\-identifikation am H1 
Experiment bei HERA', Ph.D. thesis, 1999, Universit\"{a}t Hamburg 
(in German,
available from \\
\verb+http://www-h1.desy.de/publications/theses_list.html+).
%
\bibitem{h1det} 
I. Abt {\it et al.} [H1 Collaboration], 
Nucl. Inst. Meth. {\bf A386} (1997) 310; \\
I. Abt {\it et al.} [H1 Collaboration], Nucl. Inst. Meth. {\bf A386} 
(1997) 348. 
%
\bibitem{f2c} 
%\cite{Aid:1996hj}
S.~Aid {\it et al.}  [H1 Collaboration],
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Nucl.\ Phys.\ {\bf B472} (1996) 32
[hep-ex/9604005]; \\
%\cite{Adloff:1998vb}
C.~Adloff {\it et al.}  [H1 Collaboration],
%``Measurement of D* meson cross sections at HERA and determination of the
%gluon density in the proton using NLO QCD,''
Nucl.\ Phys.\ {\bf B545} (1999) 21
[hep-ex/9812023]; \\
%\cite{Adloff:2001zj}
C.~Adloff {\it et al.}  [H1 Collaboration],
%``Measurement of D*+- meson production and F2(c) in deep inelastic  scattering
%at HERA,''
Phys.\ Lett.\ {\bf B528} (2002) 199
[hep-ex/0108039].
%
%%%%% MC models
%
\bibitem{rapgap} H.~Jung, Comp. Phys. Comm. {\bf 71} (1992) 15. 
\bibitem{lund} B. Andersson, G. Gustafson, G. Ingelman and T. Sj\"ostrand, 
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%
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%{\it et al.}
\bibitem{rxobs} H1 Collaboration, contributed paper to the Lepton-Photon
Conference 2005, Abstract \# 407, Uppsala, Sweden.
%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\end{thebibliography}
\newpage
\begin{table}
\begin{tabular}{lr}
Variation&$\frac{\displaystyle \Delta R_{cor}}{\displaystyle R_{cor}}$ [\%]\\
\noalign{\smallskip}
\hline
\noalign{\smallskip}
\parbox[t]{9cm}{Background shape determined from background model
in Fig. \ref{signal}}&-12\\
\noalign{\smallskip}
\parbox[t]{9cm}{$\Delta M(D^*)$ window reduced to 1.5 MeV}&-9\\
\noalign{\smallskip}
\parbox[t]{9cm}{Visible $D^*$ region extended down to $z(D^*)>$0.1}&-21\\
\noalign{\smallskip}
\parbox[t]{9cm}{Require $|M(D^*\pi)-2450~\rm{MeV}|~>~50$~MeV
for the $D^*p$ combinations}&+18\\
\noalign{\smallskip}
\parbox[t]{9cm}{dE/dx calibration}&$\pm$10\\
\noalign{\smallskip}
\parbox[t]{9cm}{Soft fragmentation of $D^*p(3100)$}&-5\\
\noalign{\smallskip}
\parbox[t]{9cm}{Reweighting of $\eta(D^*p(3100))$}&-3\\
\noalign{\smallskip}\hline
\noalign{\smallskip}
\parbox[t]{9cm}{Total}&-28 + 21\\
\noalign{\smallskip}\hline

\end{tabular}
\caption{Relative systematic errors on the acceptance corrected yields
ratio $R_{cor}$ for the visible $D*$ meson region.
}
\label{syst1}
\end{table}
\begin{table}
\begin{tabular}{lr}
Variation&
$\frac{{\displaystyle\Delta} \textstyle
\frac{\sigma_{vis}(D^*p(3100))}{\sigma_{vis}(D^*)}}
{\textstyle\frac{\sigma_{vis}(D^*p(3100))}{\sigma_{vis}(D^*)}}$ [\%]\\
\noalign{\smallskip}
\hline
\noalign{\smallskip}
\parbox[t]{9cm}{Background shape determined from background model
in Fig. \ref{signal}}&-14\\
\noalign{\smallskip}
\parbox[t]{9cm}{$\Delta M(D^*)$ window reduced to 1.5 MeV}&-10\\
\noalign{\smallskip}
\parbox[t]{9cm}{Visible $D^*$ region extended down to $z(D^*)>$0.1}&-8\\
\noalign{\smallskip}
\parbox[t]{9cm}{$z(D^*)$ replaced by cut in the $D^*p(3100)$ 
fragmentation variable $x_{obs}$}&-15\\
\noalign{\smallskip}
\parbox[t]{9cm}{Require $|M(D^*\pi)-2450~\rm{MeV}|~>~50$~MeV
for the $D^*p$ combinations}&+17\\
\noalign{\smallskip}
\parbox[t]{9cm}{dE/dx calibration}&$\pm$10\\
\noalign{\smallskip}
\parbox[t]{9cm}{Soft fragmentation of $D^*p(3100)$}&+28\\
\noalign{\smallskip}
\parbox[t]{9cm}{Reweighting of $\eta(D^*p(3100))$}&-4\\
\noalign{\smallskip}\hline
\noalign{\smallskip}
\parbox[t]{9cm}{Total}&-26 + 34\\
\noalign{\smallskip}\hline

\end{tabular}
\caption{Relative systematic errors on the acceptance corrected visible cross
section ratio $\sigma_{vis}(D^*p(3100))/\sigma_{vis}(D^*)$.
}
\label{syst2}
\end{table}
\newpage
\begin{figure}[p] \unitlength 1mm
 \begin{center}
 \begin{picture}(100,100)
  \put(-30,-20){\epsfig{file=H1prelim-05-072.fig1.eps,width=0.95\textwidth}}
%  \put(13,185){{\Large {\bf \fontfamily{phv}\selectfont (a)}}}  % Helvetica
%  \put(13,81){{\Large {\bf \fontfamily{phv}\selectfont (b)}}}
 \end{picture}
 \end{center}
\caption{Distributions in $M(D^* p)$ for opposite-charge $D^* p$ 
combinations. The data are
compared with a two-component background model in which 
``wrong charge $D$'' $K^\pm \pi^\pm$ combinations 
are used to describe non-charm related
background and the ``$D^*$ MC'' simulation describes background involving
real $D^*$ mesons (from ref\cite{h1cpq}).}
\label{signal}
\newpage
\end{figure}

\begin{figure}[ht]
 \begin{center}
 \begin{picture}(120,180)
\put(-20,75)
{\epsfig{figure=H1prelim-05-072.fig2a.eps,width=0.5\textwidth}}
\put(60,75)
{\epsfig
{figure=H1prelim-05-072.fig2b.eps,width=0.5\textwidth}}
\put(20,-5){\epsfig{figure=H1prelim-05-072.fig2c.eps,width=0.5\textwidth}}
  \put(0,140){{\Large {\bf \fontfamily{phv}\selectfont (a)}}}  % Helvetica
  \put(80,140){{\Large {\bf \fontfamily{phv}\selectfont (b)}}}
  \put(40,60){{\Large {\bf \fontfamily{phv}\selectfont (c)}}}
 \end{picture}
 \end{center}
\caption{Acceptance corrected ratios $\sigma_{vis}(D^*p(3100))/\sigma_{vis}(D^*)$ as
a function of the kinematic variables (a) $W$, (b) Q$^2$ and (c) $\hat{s}_{obs}$. 
Data (closed symbols) are compared with the expectation (dashed line) 
of RAPGAP 3.1 which assumes the same mechanism for $D^*$ and $D^*p(3100)$ production. Only statistical errors are shown.
\label{kine}}
\end{figure}

\begin{figure}[ht]
 \begin{center}
 \begin{picture}(120,180)
\put(-20,75)
{\epsfig{figure=H1prelim-05-072.fig3a.eps,width=0.5\textwidth}}
\put(60,75)
{\epsfig{figure=H1prelim-05-072.fig3b.eps,width=0.5\textwidth}}
\put(-20,-5)
{\epsfig{figure=H1prelim-05-072.fig3c.eps,width=0.5\textwidth}}
\put(60,-5)
{\epsfig{figure=H1prelim-05-072.fig3d.eps,width=0.5\textwidth}}
  \put(0,140){{\Large {\bf \fontfamily{phv}\selectfont (a)}}}  % Helvetica
  \put(80,140){{\Large {\bf \fontfamily{phv}\selectfont (b)}}}
  \put(0,60){{\Large {\bf \fontfamily{phv}\selectfont (c)}}}
  \put(80,60){{\Large {\bf \fontfamily{phv}\selectfont (d)}}}
 \end{picture}
 \end{center}
\caption{Acceptance corrected ratios $\sigma_{vis}(D^*p(3100))/\sigma_{vis}(D^*)$ as
a function of $D^*$ variables (a) $\eta(D^*)$ and (b) $p_t(D^*)$ both 
in the laboratory frame, (c) $z(D^*)$ and (d) $\eta^*(D^*)$ in the hadronic
centre-of-mass system. 
Data (closed symbols) are compared with the expectation (dashed line) 
of RAPGAP 3.1 which assumes the same mechanism for $D^*$ and $D^*p(3100)$ production. Only statistical errors are shown.
\label{dstar}}
\end{figure}

\begin{figure}[ht]
 \begin{center}
 \begin{picture}(120,180)
\put(-20,75)
{\epsfig{figure=H1prelim-05-072.fig4a.eps,width=0.5\textwidth}}
\put(60,75)
{\epsfig{figure=H1prelim-05-072.fig4b.eps,width=0.5\textwidth}}
\put(-20,-5)
{\epsfig{figure=H1prelim-05-072.fig4c.eps,width=0.5\textwidth}}
\put(60,-5)
{\epsfig{figure=H1prelim-05-072.fig4d.eps,width=0.5\textwidth}}
  \put(0,140){{\Large {\bf \fontfamily{phv}\selectfont (a)}}}  % Helvetica
  \put(80,140){{\Large {\bf \fontfamily{phv}\selectfont (b)}}}
  \put(0,60){{\Large {\bf \fontfamily{phv}\selectfont (c)}}}
  \put(80,60){{\Large {\bf \fontfamily{phv}\selectfont (d)}}}
 \end{picture}
 \end{center}
\caption{Differential $(D^*p(3100))$ cross sections as
a function of $D^*p$ variables (a) $\eta(D^*p)$ and (b) $p_t(D^*p)$ both 
in the laboratory frame, (c) $z(D^*p)$ and (d) $\eta^*(D^*p)$ in the hadronic
centre-of-mass system. 
Data (closed symbols) are compared with the expectation (dashed line) 
of RAPGAP 3.1 which assumes the same mechanism for $D^*$ and $D^*p(3100)$ 
production. Only statistical errors are shown.
\label{dsp}}
\end{figure}

\begin{figure}[ht]
 \begin{center}
 \begin{picture}(120,180)
\put(20,80)
{\epsfig{figure=H1prelim-05-072.fig5a.eps,width=0.5\textwidth}}
\put(20,0)
{\epsfig{figure=H1prelim-05-072.fig5b.eps,width=0.5\textwidth}}
  \put(10,130){{\Large {\bf \fontfamily{phv}\selectfont (a)}}}  % Helvetica
  \put(10,50){{\Large {\bf \fontfamily{phv}\selectfont (b)}}}
 \end{picture}
 \end{center}
\caption{Sketch of the method to reconstruct the visible charm quark energies
in $ep$ scattering close to threshold. (a) The hadrons in the photon hemisphere
of the hadronic centre-of-mass system are projected to the plane perpendicular
to the photon direction. (b) The hadrons in the $D*$ hemisphere are used
to reconstruct the visible charm quark energy.  
\label{fmethod}}
\end{figure}
\begin{figure}[ht]
 \begin{center}
 \begin{picture}(120,180)
\put(20,75)
{\epsfig{figure=H1prelim-05-072.fig6a.eps,width=0.5\textwidth}}
\put(20,-5)
{\epsfig{figure=H1prelim-05-072.fig6b.eps,width=0.5\textwidth}}
  \put(45,140){{\Large {\bf \fontfamily{phv}\selectfont (a)}}}  % Helvetica
  \put(45,60){{\Large {\bf \fontfamily{phv}\selectfont (b)}}}
 \end{picture}
 \end{center}
\caption{Acceptance corrected ratio $\sigma_{vis}(D^*p(3100))/\sigma_{vis}(D^*)$ as 
a function of the $D^*$ hadronization fraction $x_{obs}(D^*)$ in (a) 
and differential cross section $d\sigma_{vis}(D^*p(3100))/dx_{obs}(D^*p)$ in (b).
Data (closed symbols) are compared with the expectation (dashed line) of 
RAPGAP 3.1 
which assumes the same mechanism for $D^*$ and $D^*p(3100)$ production.
 Only statistical errors are shown.
\label{xobs}}
\end{figure}

\end{document}

