Observation of $K_s^0K_s^0$ resonances \\ in deep inelastic scattering at HERA
M. Barbi
Inclusive $K_s^0K_s^0$ production in deep inelastic $ep$ scattering at HERA has been studied with the ZEUS detector using an integrated luminosity of $120$~pb$^{-1}$. Two states are observed at masses of $1537^{+9}_{-8}$~MeV and $1726\pm 7$~MeV, as well as an enhancement around $1300$~MeV. The state at $1537$~MeV is consistent with the well established \fprime. The state at $1726$~MeV may be the glueball candidate $f_0(1710)$. However, it's width of $38^{+20}_{-14}$~MeV is narrower than $125\pm10$~MeV observed by previous experiments for the $f_0(1710)$.
aipcheck.tex
%
% $Id: aipcheck.tex,v 1.7 2002/01/11 19:50:46 frank Exp $
%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% Testing for potential problems with this class
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

\newif\ifproblem
\newif\iftimesok

\makeatletter
\def\IfStandaloneCheck{\def\next{aipcheck}
  \edef\currjob{\jobname}
  \edef\next{\meaning\next}
  \edef\currjob{\meaning\currjob}
  \ifx\currjob\next
    \expandafter\@firstoftwo
  \else
    \expandafter\@secondoftwo
  \fi
}
\makeatother

\typeout{***********************************************}
\typeout{*}
\typeout{* Testing if all files required for the aipproc}
\typeout{* class are available ...}
\typeout{*}
\typeout{***********************************************}

\typeout{*}
\typeout{* Looking for LaTeX2e ... }
\ifx\documentclass\undefined
 \typeout{*}
 \typeout{* Sorry this is a fatal error:}
 \typeout{*}
 \typeout{* The aipproc class can only be used with LaTeX2e which is}
 \typeout{* the standard LaTeX since 1994!}
 \typeout{*}
 \typeout{* Please make sure that your version of LaTeX is up-to-date}
 \typeout{* before attempting to use this class.}
 \typeout{*}
 \expandafter\stop
\else
 \typeout{* ... ok }
\fi


\def\next#1/#2/#3\next{#1#2}
\typeout{*}
\typeout{* Testing that LaTeX2e is not too old ... }
\ifnum\expandafter\next\fmtversion\next<199612 \relax
 \typeout{* ... what a vintage! }
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 \typeout{*}
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 \typeout{* Please make sure that your version of LaTeX is up-to-date}
 \typeout{* before attempting to use this class.}
 \typeout{*}
 \expandafter\stop
\else
 \ifnum\expandafter\next\fmtversion\next<199806 \relax
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   \typeout{* hasn't been tested with your release.}
   \typeout{*}
   \typeout{* We believe that it will probably work, but if you encounter}
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   \typeout{*}
   \typein{* Type <return> to continue ...}
   \problemtrue
 \else
   \typeout{* ... ok }
 \fi
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\IfFileExists{aipproc.cls}
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     \typeout{* Before you can use the aipproc class you have to unpack}
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     \typeout{* Run LaTeX on the file 'aipproc.ins', e.g.,}
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     \typeout{* or whatever is necessary on your installation to process}
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     \typeout{* aipproc.cls \space and \space aip-*.clo}
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     \typeout{* After that retry processing this guide.}
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     \typeout{*}
     \typeout{* Sorry this is a fatal error:}
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     \typeout{* The aip-8s.clo file which is part of the aipproc distribution}
     \typeout{* must be installed in a directory which is searched by LaTeX.}
     \typeout{*}
     \typeout{* Please install this file and retry.}
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\typeout{*}
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\IfFileExists{aip-8d.clo}
    {
     \typeout{* ... ok }
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     \typeout{*}
     \typeout{* Sorry this is a fatal error:}
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     \typeout{* The aip-8d.clo file which is part of the aipproc distribution}
     \typeout{* must be installed in a directory which is searched by LaTeX.}
     \typeout{*}
     \typeout{* Please install this file and retry.}
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     \stop
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\typeout{*}
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\IfFileExists{aip-6s.clo}
    {
     \typeout{* ... ok }
    }
    {
     \typeout{* ... not found! }
     \typeout{*}
     \typeout{* Sorry this is a fatal error:}
     \typeout{*}
     \typeout{* The aip-6s.clo file which is part of the aipproc distribution}
     \typeout{* must be installed in a directory which is searched by LaTeX.}
     \typeout{*}
     \typeout{* Please install this file and retry.}
     \typeout{*}
     \stop
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    {
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     \typeout{*}
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     \typeout{* must be installed in a directory which is searched by LaTeX.}
     \typeout{*}
     \typeout{* Please install this file and retry.}
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	  \typeout{* Sorry this is a fatal error:}
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	  \typeout{* nor fix2col.sty.}
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	  \typeout{* This means that it is either too old or incompletely}
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	  \typeout{* fixltx2e.sty is part of the standard LaTeX distribution}
	  \typeout{* since 1999; fix2col.sty is an earlier version of this}
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	  \typeout{*}
	  \typeout{* Best solution is to get the latest LaTeX distribution.}
	  \typeout{* If this is impossible for you, download fix2col.sty.}
	  \typeout{* You can get this software from a CTAN host.}
          \typeout{* Refer to http://www.ctan.org and search for "fix2col".}
	  \typeout{*}
	  \typeout{* After you have updated your LaTeX distribution}
	  \typeout{* retry processing this guide.}
	  \stop
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\typeout{*}
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    {
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     \typeout{*}
     \typeout{* Sorry this is a fatal error:}
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     \typeout{* The fontenc package, which is part of standard LaTeX}
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     \typeout{*}
     \typeout{* Please make sure that your version of LaTeX is okay}
     \typeout{* before attempting to use this class. The LaTeX distribution}
     \typeout{* contains the file "ltxcheck.tex" which can be used to}
     \typeout{* test the basic functionality and integrity of your installation.}
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     \typeout{*}
     \typeout{* Sorry this is a fatal error:}
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     \typeout{* The calc package, which is part of standard LaTeX}
     \typeout{* (tool distribution) has to be installed at the site}
     \typeout{* to run the aipproc class.}
     \typeout{*}
     \typeout{* The fact that it cannot be found either means that}
     \typeout{* this LaTeX release is too old or that it was installed}
     \typeout{* only in parts.}
     \typeout{*}
     \typeout{* Please make sure that the tools distribution of LaTeX}
     \typeout{* is installed before attempting to use this class.}
     \typeout{*}
     \typeout{* (You might be able to get calc.sty separately for your}
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     \typeout{* Please also note that the aipguide.tex documentation}
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     \typeout{* effects (which  will now fail).}
     \typeout{*}
     \typein{* Type <return> to continue ...}
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\typeout{*}
\typeout{* Looking for times.sty ... }
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     \typeout{* you have to specify the option "cmfonts" which result in}
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     \typeout{* You can also try using the class in the following way:}
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     \typeout{* \space\space \string\documentclass[cmfonts]{aipproc}}
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     \typein{* Type <return> to continue ...}
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     \typeout{* The fact that this package cannot be found either means that}
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     \typein{* Type <return> to continue ...}
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           \typeout{* The fact that this package is only partially installed}
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           \typeout{* You can use the aipproc class without this package but }
           \typeout{* you have to specify the option "cmfonts" which result in}
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           \typein{* Type <return> to continue ...}
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  \typeout{*}
  \typeout{* Looking for #1#3.fd or #2#3.fd ... }
  \IfFileExists{#1#3.fd}
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    {
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     \typeout{* The fact that this package cannot be found either means that}
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     \typein{* Type <return> to continue ...}

     \def\textdegree{$^\circ$}         % used below but now
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\makeatletter

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barbi.hadron03.tex
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\begin{document}

\title{Observation of $K_s^0K_s^0$ resonances \\
in deep inelastic scattering at HERA}


\author{M. Barbi}{
  address={McGill University, 
        Physics Department\\
        Montreal, Quebec\\ 
	Canada}
	\\ (on behalf of the ZEUS Collaboration)
}

\begin{abstract}
 Inclusive $K_s^0K_s^0$ production
in deep inelastic $ep$ scattering at HERA has been studied
with the ZEUS detector 
using an integrated luminosity of $120$~pb$^{-1}$. 
Two states are observed at masses of 
$1537^{+9}_{-8}$~MeV and $1726\pm 7$~MeV, 
as well as an enhancement around $1300$~MeV.
The state at $1537$~MeV is consistent with the well established
\fprime. The state at $1726$~MeV may be the glueball candidate
$f_0(1710)$. However, it's width of $38^{+20}_{-14}$~MeV is narrower 
than $125\pm10$~MeV observed by previous experiments for the $f_0(1710)$.
\end{abstract}

\maketitle

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%% MAINMATTER
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

\section{Introduction}

The $K_s^0K_s^0$ system is expected to couple to scalar
and tensor glueballs. This has motivated intense 
experimental and theoretical study during the past few years
\cite{rmp:v71:1411,hep-ex/0101031}.
Lattice QCD calculations \cite{glueball1,glueball2}
predict the existence of a scalar 
glueball with a mass of $1730\pm 100$ MeV and 
a tensor glueball at $2400\pm 120$ MeV.
The scalar glueball can mix with $q\overline{q}$ states with $I=0$ from 
the scalar meson nonet, leading to three $J^{PC}=0^{++}$ states whereas
only two can fit into the nonet.
Experimentally, four states with $J^{PC}=0^{++}$ and $I=0$ have been 
established \cite{pdg}: $f_0(980)$, $f_0(1370)$, $f_0(1500)$ and $f_0(1710)$.

The state most frequently considered to be a glueball candidate 
is $f_0(1710)$ \cite{pdg} , but its gluon content has not 
yet been established. 
This state was first observed in radiative $J/\psi$ 
decays \cite{BES96} and
its angular momentum $J=0$ was established by the WA102 experiment 
using a partial-wave analysis in the $K^+K^-$ and $K_s^0K_s^0$ 
final states\cite{WAf1710} .
Observation of $f_0(1710)$ in $\gamma\gamma$ 
collisions may indicate a large quark content.
A recent publication from L3 \cite{L3} 
reports the observation of two states in $\gamma\gamma$ collisions
above $1500$ MeV, the well-established $f_2^\prime(1525)$ \cite{pdg}
and a broad resonance at 1760 MeV. 
It is not clear if the latter state is the $f_0(1710)$.
% or a radially excited state. 

The $ep$ collisions at HERA provide an opportunity to study resonance
production in a new environment. Production of $K_s^0$ particles 
has been studied previously at HERA \cite{epj:c2:77,zfp:c68:29,np:b480:3}.
In this contribution, the first observation of resonances in the 
$K_s^0K_s^0$ final state in inclusive deep inelastic $ep$ scattering 
(DIS) is reported \cite{hep-0308006}.


\section{Event selection and $K_s^0$-pair candidates}


A detailed description of the ZEUS detector can be found 
elsewhere~\cite{zeus:1993:bluebook}.

The data used for this study correspond to a total integrated luminosity of 
120 pb$^{-1}$ collected in ZEUS during the 1996-2000 running period. 

The inclusive neutral current DIS process 
$e(k)+p(P) \rightarrow e(k^\prime)+X$
can be 
described in terms of the following variables:
the negative of the invariant-mass 
squared of the exchanged virtual photon,
$Q^2~=~-q^2~=~-$ $(k-k^\prime)^2$; the fraction of the lepton 
energy transferred 
to the proton in the proton rest frame,
$y=(q\cdot P)/(k\cdot P)$;
and the Bjorken scaling variable, 
$x=Q^2/(2P\cdot q)$.

A three-level trigger system was used to select events online 
\cite{zeus:1993:bluebook}.
The inclusive DIS selection was defined by requiring an
electron found in the Uranium Calorimeter, and further requirements were applied
to ensure a well defined data sample~\cite{hep-0308006}.

Oppositely charged track 
pairs reconstructed by the ZEUS central tracking detector (CTD) and 
assigned to a secondary vertex were selected and combined 
to form $K_s^0$ candidates. 
Both tracks were assigned the mass of a charged pion and the 
invariant-mass $M(\pi^+\pi^-)$ was calculated. 
Only events with at least one pair of $K_s^0$ candidates were selected.
The invariant mass of the $K_s^0$ pair candidate $M(K_s^0,K_s^0)$
was reconstructed in the range \mbox{$0.995~<~M(K_s^0K_s^0)~<2.795$ GeV}.
A detailed description of the $K_s^0$ pair candidate selection can be found
in~\cite{hep-0308006}.

Figure \ref{fig:Ksmass} shows the distribution in $x$ and $Q^2$ 
of selected events containing at least one 
pair of $K_s^0$ candidates. 
%The virtual photon-proton 
%center of mass energy is in the range \mbox{$50<W<250$ GeV}.

\begin{figure}
\includegraphics[height=.4\textheight]{DESY-03-098_1.eps}
 \caption{The distribution of $\pi^+\pi^-$ invariant mass 
for events with at least two $K_s^0$ candidates 
passing all selection cuts. The solid line shows the result of a
fit using one linear and two Gaussian functions.}
\label{fig:Ksmass} 
\end{figure}

Figure~\ref{fig:q2vsxbj} shows the $M(\pi^+\pi^-)$ distribution in the range
\mbox{$0.45<M(\pi^+\pi^-)<0.55$ GeV} after the $K_s^0$ pair candidate selection.

\begin{figure}
\includegraphics[height=.4\textheight]{DESY-03-098_2.eps}
 \caption{The distribution in $x$ and $Q^2$ of events passing all selection cuts.
The dashed lines delineate approximately the 
kinematic region selected. The solid
line indicates the kinematic limit for HERA running with 920 GeV protons.}
\label{fig:q2vsxbj}
\end{figure}

\section{Results}

The $K_s^0K_s^0$ spectrum may have a strong enhancement near the
$K_s^0K_s^0$ threshold due to the $f_0(980)$/$a_0(980)$
state \cite{prd:v32:189,pl:b489:24,hep-ph/0202157}.
Since the high $K_s^0K_s^0$ mass 
is the region of interest for this analysis, the complication 
due to the threshold region is avoided by imposing the cut 
\mbox{$cos\theta_{K_s^0K_s^0}<0.92$}, where $\theta_{K_s^0K_s^0}$ 
is the opening angle between the two $K_s^0$ candidates in the 
laboratory frame. 


After applying all selections, 2553 $K_s^0$-pair candidates were
found in the range
$0.995<M(K_s^0K_s^0)<2.795$ GeV, where
$M(K_s^0K_s^0)$ was calculated using the $K_s^0$ mass of $497.672~$MeV
\cite{pdg}. The momentum resolution of the CTD leads to an average
$M(K_s^0K_s^0)$ resolution which ranges from $7$ MeV in the 
$1300$ MeV mass region to 10 MeV in the $1700$ MeV region.
Figure \ref{fig:KKmass} shows the measured $K_s^0K_s^0$ invariant-mass 
spectrum.
Two clear peaks are 
seen, one around 1500 MeV and the other around 1700 MeV,
along with an enhancement around 1300 MeV.
The data for \mbox{$\cos{\theta_{K_s^0K_s^0}}>0.92$} are also
shown. 

\begin{figure}
  \includegraphics[height=.4\textheight]{DESY-03-098_3.eps}
  \caption{The $K_s^0K_s^0$ invariant-mass spectrum for $K_s^0$ pair candidates with
$cos\theta_{K_s^0K_s^0}<0.92$ (filled circles). 
The thick solid line is the result 
of a fit using three Breit-Wigners (thin solid lines) and a background
function (dotted-dashed line). 
The $K_s^0$ pair candidates that fail the $cos\theta_{K_s^0K_s^0}<0.92$
cut are also shown (open circles).}
\label{fig:KKmass}
\end{figure}


The distribution of Fig.~\ref{fig:KKmass} was fitted 
using three modified relativistic Breit-Wigner (MRBW) 
distributions 
and a background function $U(M)$;

\begin{equation}
F(M) = \sum_{i=1}^{3}
(\frac{m_{*,i}\Gamma_{d,i}}{(m_{*,i}^2-M^2)^2+m_{*,i}^2\Gamma_{d,i}^2})
+ U(M)~,
\end{equation}

where $\Gamma_{d,i}$ is the effective resonance width, 
which takes into account spin and large width effects \cite{bwigner},
$m_{*,i}$ is the resonance mass, and $M$ is $K^0_sK^0_s$ invariant 
mass. The background function is

\begin{equation}
U(M)~=~A\cdot (M-2m_{K_s^0})^{B}\cdot e^{-C \sqrt{M-2m_{K_s^0}}}~,
\label{bgndfunc}
\end{equation}

where $A$, $B$ and $C$ are free parameters and 
$m_{K_s^0}$ is the $K_s^0$ mass defined by Hagiwara et al \cite{pdg}. 
Monte Carlo studies showed that effects of the track-momentum resolution
on the mass reconstruction were small compared to the measured widths 
of the states. Therefore the resolution effects were ignored in the fit.


Below $1500$ MeV, a region strongly affected by the 
$\cos{\theta_{K_s^0K_s^0}}$ cut, a peak is seen around 
$1300$ MeV where a contribution from $f_2(1270)/a_2^0(1320)$ is expected.
This mass region was fitted with a single Breit-Wigner.

Above $1500$ MeV, the lower-mass state has a fitted mass of 
$1537^{+9}_{-8}$ MeV and a width of $50^{+34}_{-22}$ MeV, in good 
agreement with the well established $f_2^\prime(1525)$.
The higher-mass state has a fitted mass of $1726 \pm 7$ MeV and
a width of $38^{+20}_{-14}$ MeV.  
The widths reported here were stable, within statistical errors,
to a wide variation of fitting methods including those using 30 MeV 
bins rather than the default 15 MeV bins.
The width is 
narrower than the PDG value
($125 \pm10$ MeV) \cite{pdg} reported for $f_0(1710)$, but when 
it is fixed to this value, 
the fit is still acceptable. 
%For the purposes of the following 
%discussion, this state is referred to as $f_0(1710)$.

%The masses, widths and number of events from the fit 
%with statistical errors are given in the top row of Table~\ref{table1}.
%It should be noted that
%there are correlations between the obtained parameters. In particular the
%width and the number of events for each state are highly correlated.
%The mass spectrum is 
%also consistent with the background function at higher masses, but masses 
%above 2795 MeV were not included in the fit due to limited statistics.
%The sensitivity of the data to the widths of the resonances was studied. 
%Several fits were performed fixing the width of the states 
%$f_2^\prime(1525)$ and $f_0(1710)$ to their PDG values; the results 
%are shown in rows 2 to 4 of Table \ref{table1}.

%\begin{table}
%  \small
%  \centering
%\begin{tabular}{|c|c|c|c|c|c|c|c|c|c|c|c|c|c|} \hline
%Fit
%&$\chi^2/N$ 
%&\multicolumn{3}{c|}{ $f_2(1270)/a_2^0(1320)$}
%&\multicolumn{3}{c|}{$f_2^\prime(1525)$} 
%&\multicolumn{3}{c|}{ $f_0(1710)$} 
%&\multicolumn{3}{c|}{ $f_J(1980)$} 
%\\ \hline 
%&
%& mass & width & events 
%& mass & width & events 
%& mass & width & events 
%& mass & width & events 
%\\ \hline
%1 & 0.97
%& $1274^{+17}_{-16}$ & $244^{+85}_{-58}$   & $414^{+184}_{-125}$ 
%& $1537^{+9}_{-8}$   & $50^{+34}_{-22}$    & $84^{+41}_{-31}$ 
%& $1726\pm 7$   & $38^{+20}_{-14}$    & $74^{+29}_{-23}$ 
%&    &    &   
%\\ \hline
%2 & 0.96
%& $1272\pm 16$ & $240^{+76}_{-55}$   & $420^{+167}_{-122}$ 
%& $1539\pm 10$ & $76$                & $107\pm 30$ 
%& $1727\pm 7$   & $39\pm 20$    & $76^{+28}_{-24}$ 
%&    &    &   
%\\ \hline
%3 & 1.02
%& $1276\pm 16$ & $258^{+80}_{-59}$   & $480^{+190}_{-141}$ 
%& $1536\pm 8$   & $49^{+30}_{-21}$    & $85^{+38}_{-27}$ 
%& $1726\pm 13$ & $125$               & $122\pm 40$ 
%&    &    &   
%\\ \hline
%4 & 1.02
%& $1274\pm 15$ & $251^{+72}_{-55}$   & $476^{+176}_{-131}$ 
%& $1538\pm 10$ & $76$                & $108^{+31}_{-29}$  
%& $1728\pm 13$ & $125$               & $120^{+41}_{-38}$ 
%&       &    &   
%\\ \hline
%5 & 1.00
%& $1283\pm 15$ & $260^{+70}_{-55}$   & $506^{+218}_{-122}$ 
%& $1540^{+12}_{-10}$ & $70^{+43}_{-30}$    & $116^{+59}_{-42}$ 
%& $1727\pm 7$   & $47^{+23}_{-15}$    & $91^{+34}_{-26}$ 
%& $1970^{+33}_{-45}$ & $138^{+173}_{-89}$  & $74\pm 40$ 
%\\ \hline
%\multicolumn{14}{|c|}{Particle Data Group 2002 Values (MeV) \cite{pdg} } \\ \hline
%&
%&\multicolumn{3}{c|}{ $1275.5 \pm1.2$, $185^{+3.4}_{-2.6}$ }
%&\multicolumn{3}{c|}{ $1525 \pm5$, $76 \pm10$              } 
%&\multicolumn{3}{c|}{ $1713 \pm6$, $125 \pm10$             } 
%&\multicolumn{3}{c|}{                                      } 
%\\  
%&
%&\multicolumn{3}{c|}{ $1318 \pm0.6$, $104.7 \pm1.9$  }
%&\multicolumn{3}{c|}{              } 
%&\multicolumn{3}{c|}{              } 
%&\multicolumn{3}{c|}{              } 
%\\ \hline 
%\hline
%\end{tabular}
%  \caption{\it 
%Normalized $\chi^2$, masses in MeV, widths in MeV, 
%and number of events extracted from the $K_s^0K_s^0$ invariant mass
%fits (errors are statistical only.) 
%Widths reported without
%errors were fixed to the PDG values listed in the last row.}
%\label{table1}
%%\end{sidewaystable} 
%\end{table}

It was found that 93\% of the $K_s^0$-pair candidates selected within the 
detector and trigger acceptance are in the target region of the Breit 
frame \cite{bk:1972:1,zerw:zfp:237}, the hemisphere containing the proton remnant. Of 
the $K_s^0$-pair candidates in the target region, 78\% are in the 
region $x_{p}=2p_B/Q > 1$, 
where $p_B$ is the absolute momentum of the $K_s^0K_s^0$ in the Breit frame.
High $x_{p}$ corresponds to production of the $K_s^0$-pair in a region
where sizeable initial state gluon radiation may be expected. This is in
contrast to the situation at $e^+e^-$ colliders where the particles 
entering the hard scattering are colourless.  

% ----------------------------------------------------------------------------
%       Our Conclusions
% ----------------------------------------------------------------------------
\section{Conclusions}
\label{sec-con}

The first observation in $ep$ deep inelastic scattering of a state 
at $1537$ MeV, consistent with 
$f^\prime_2(1525)$, and another at 1726 MeV, close to $f_0(1710)$, 
is reported. 
There is also an enhancement near 1300 MeV which may arise from the 
production of $f_2(1270)$ and/or $a_2^0(1320)$ states.
The width of the state at $1537$ MeV
is consistent with the PDG value for the $f_2^\prime(1525)$.
The state at 1726 MeV has a mass consistent with the glueball candidate
$f_0(1710)$, and is found in a gluon-rich region of phase space.
However, it's width of $38^{+20}_{-14}$ MeV is narrower than the PDG value 
of 125$\pm$10 MeV for the $f_0(1710)$.


%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%% BACKMATTER
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

%\begin{theacknowledgments}
%We thank the DESY directorate for their strong support and 
%encouragement. The special efforts of the HERA machine group 
%in the collection of the data used in this paper are 
%gratefully acknowledged. We are grateful for the support of the
%DESY computing and network services. The design, construction 
%and installation of the ZEUS detector have been made 
%possible by the ingenuity and effort of many people from DESY 
%and home institutes who are not listed as authors.
%We also thank F. Close, S. Godfrey and H. Lipkin for their 
%valuable comments and advice.
%\end{theacknowledgments}

\bibliographystyle{aipproc}

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 {\typeout{}
  \typeout{******************************************}
  \typeout{** Please run "bibtex \jobname" to optain}
  \typeout{** the bibliography and then re-run LaTeX}
  \typeout{** twice to fix the references!}
  \typeout{******************************************}
  \typeout{}
 }

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\bibitem{hep-ex/0101031} E. Klempt, Preprint \mbox{hep-ex/0101031} (2000).
\bibitem{glueball1} C.J. Morningstar, M. Peardon, Phys. Rev. D 60 (1999) 034509.
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%(2003).
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\newblock {\em The {ZEUS} Detector}.
\newblock Status Report (unpublished), DESY (1993),
\newblock available on
%  \texttt{http://www-zeus.desy.de/bluebook/bluebook.html}\relax
\url{http://www-zeus.desy.de/bluebook/bluebook.html}\relax
\relax
\bibitem{prd:v32:189}
S. Godfrey and N. Isgur,
\newblock Phys.\ Rev.{} {\bf D32},~189~(1985)\relax
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\newblock Phys.\ Lett.{} {\bf B~489},~24~(2000)\relax
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\bibitem{hep-ph/0202157}
T. Barnes,
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\bibitem{breit2} K.H. Streng, T.F. Walsh and P.M. Zerwas, Z. Phys. C 2 (1979) 237.

\end{thebibliography}

\end{document}

our_def.tex
% Avoid indentation:
\setlength{\parindent}{0mm}
% KsKs aliases:
\newcommand{\ra}{\rightarrow}
\newcommand{\kk}{$K_s^0K_s^0$}
\newcommand{\Ks}{$K_s^0$}
\newcommand{\Lb}{$\overline{\Lambda}$}
\newcommand{\cosKK}{$\cos\theta_{KK}<0.92$}
\newcommand{\fprime}{$f_2^{\prime}(1525)$}
% A useful Journal macro
\def\Journal#1#2#3#4{{#1} {\bf #2}, #3 (#4)}
% Some useful journal names
\def\NCA{\em Nuovo Cimento}
\def\NIM{\em Nucl. Instrum. Methods}
\def\PR{\em Phys. Rep.}
\def\NIMA{{\em Nucl. Instrum. Methods} A}
\def\NPB{{\em Nucl. Phys.} B}
\def\PLB{{\em Phys. Lett.}  B}
\def\PRL{\em Phys. Rev. Lett.}
\def\PRD{{\em Phys. Rev.} D}
\def\ZPC{{\em Z. Phys.} C}
\def\CPC{\em Comp. Phys. Comm.}
\def\RMP{{\em Rev. Mod. Phys.}}
\def\EPJC{{\em Eur. Phys. J.} C}
% Define a quark model nonet (borrowed from Klempt's paper)
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{
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hep-ex0310002.extracted_bib
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