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\begin{document}
\begin{center}
{\Large\bf Recent results on $\psi(2s)$ and $\chi_c$ from BES}
\par
\vspace{.40in}
{\large Yongsheng Zhu\\
\smallskip
IHEP,Chinese Academy of Sciences \\
P.O.Box 918(1),Beijing 100039,China\\
Representing The BES Collaboration\\}
\end{center}

\section{Introduction}
\hspace{1cm}The BES collaboration has become well known due to it's successful
precision measurement on $\tau$ lepton mass[1], while it's succesive works 
on $J/\psi,\psi(2s),D_s$ make the further contribution for the $\tau$ charm
physics[2].  By now, BES has collected 9 million  $J/\psi$, 3.6 million 
$\psi(2s)$
events and 22.3 $pb^{-1}$ $\tau, D_s ,D$ data sample.  Vevy soon BES will
complete it's upgrade task, therefore it will significantly improve the power 
of particle ID and secondary vertex finding, the precision of the momentum 
measurement, and enlarge the solid angle coverage.  The more and better physics
results can be expected.
\par
\hspace{0.4cm}As BES has the largest $\psi(2s)$ data sample in the world, we 
are able to investigate many channels of $\psi(2s)$ decays and to extend our 
study to other chamonium states, such as $\chi_c$, $\eta_c$ etc.. In this talk
I will concentrate on the results which are newely measured or precision 
improved by BES Collaboration.  

\section{BES detector}
\hspace{1cm}The detector BES has been described in reference [3].
The principal sub-detectors of BES are central drift chamber (CDC), main drift
chamber (MDC), barrel and endcap shower counters (BSC,ESC), barrel and endcap
time of flight counters (BTOF,ETOF), magnet (with 0.4 T magnetic field), muon 
counters (MUC) and luminosity monitor (LUM).  Here we summarize only some 
elements.   The CDC consisting of four layers of 
sense wires is used for trigger purposes.
Charged track reconstruction is performed by means of the cylindrical MDC 
which covers 85\% of the $4\pi$ solid angle. Together with a 0.4 T magnetic 
field, the MDC provides a momentum resolution of $\sigma_p/p=0.017\sqrt{1+p^2}$
, p in GeV/c.  Measurements of $dE/dx$ with resolution 8.5\% allow particle 
identification. The BTOF consists of 48 scintillation counters, which cover 
76\% of $4\pi$ solid angle and provide a time resolution of 330 ps for 
Bhabha tracks.    Between the BTOF and the coil of the solenoid is the BSC, 
which consists of 24 layers of alternating 0.5 radiation-length lead sheets and
self-quenching streamer mode tubes.     The  solid angle coverage is about
80\% of 4$\pi$ and the energy resolution $\sigma_E/E$ is 0.22/$\sqrt{E(GeV)}$.
Finally, a three-layer iron flux return instrumented for muon identification
yields spatial resolution $\sigma_z=5 cm$,$\sigma_{r\varphi}=3 cm$ over
65\% of $4\pi$  for muons with momentum greater than 550 MeV/c.

\section{The measurements of $\psi(2s)$ decays}

\subsection{Branching fraction of $\psi(2s) \rightarrow \tau^+\tau^-$}

\hspace{1cm}Using 1.27 million produced $\psi(2s)$ events, the branching 
fraction for  $\psi(2s) \rightarrow \tau^+\tau^-$ 
decay has been measured with the result of
\begin{displaymath}
B(\psi(2s) \rightarrow \tau^+\tau^-) = (3.5 \pm 0.5 \pm 0.6) \times 10^{-3} 
\end{displaymath} 
Assuming $e-\mu-\tau$ universality and considering lepton mass, following
relation holds:
\begin{displaymath}
B_{ee}=B_{\mu\mu}=B_{\tau\tau}/0.3885.
\end{displaymath}
Our measurement for $B_{\tau\tau}$, together with existing data of
$B(\psi(2s) \rightarrow e^+e^-)= (8.8\pm 1.3) \times 10^{-3}$
and $B(\psi(2s) \rightarrow \mu^+\mu^-)= (7.7\pm 1.7) \times 10^{-3}$,
 satisfies the prediction of $e-\mu-\tau$
universality hypothesis.   

\subsection{The hadronic decays of $\psi(2s)$}
\subsubsection{Branching fractions of $\psi(2s)$ decays to VP and VT mesons}
\par
\hspace{0.4cm}There has been a long-standing puzzle in $J/\psi$ and $\psi(2s)$
decays into vector plus pseudoscalar exclusive final states.  As early as 1983,
The Mark II  Collaboration first found two final states,$\rho\pi$ and
$K^{*\pm}K^{\mp}$, unobservable in $\psi(2s)$ decays, with a data sample of
$1.02 \times 10^6$ produced $\psi(2s)$,while both of them have a
large branching fraction in $J/\psi$ decays[4]. It has been noted that the
ratios of branching fractions of $\psi(2s)$ and $J/\psi$ to these two final
states[5]: $Q_{\rho\pi}<0.0063$, $Q_{K^*\overline{K}}<0.011$, 
badly violated the
expectation of PQCD that, for any final hadronic state h, the ratio $Q_h$ scales
as the ratio of the 3 gluon widths which are proportional to the leptonic
widths devided by the full widths:

\begin{displaymath}
Q_h  \equiv \frac{B(\psi(2s) \rightarrow h)} {B(J/\psi\rightarrow h)}=
\frac{B(\psi(2s) \rightarrow ggg)} {B(J/\psi\rightarrow ggg)}=
\frac{B(\psi(2s) \rightarrow e^+e^-)} {B(J/\psi\rightarrow e^+e^-)}=
(14.7 \pm 2.3)\%
\end{displaymath}
where the updated values of leptonic branching fractions from Particle Data 
Table [5] are used.  More recently, the Crystal Ball experiment observed 
another two decays of the $\psi(2s)$ into VP final states, $\gamma\eta$ and
$\gamma\eta\prime$, where the vector is a photon, that are anomalously
suppressed[6]. However, the Crystal Ball results have never been formally
published, and the Mark II measurements of $\psi(2s)$ decays have not been
renewed till 1995 Beijing Lepton Photon Conference.
\par
\hspace{0.4cm}With 1.27 million produced $\psi(2s)$ events, BES collaboration
reported on the 1995 Lepton-Photon Conference the preliminary results of the
branching fractions of the $\psi(2s)$ decays into a vector and a pseudoscalar
mesons, $\rho\pi, K^{*\pm}K^{\mp}$, $K^{*0}\overline{K^0}$.
BES also reported the first measurement on the branching 
fractions of $\psi(2s)$ decay into vector-tensor final states, $\omega f_2$
and $\rho a_2$. It is found that
all these decays are substantially suppressed in the $\psi(2s)$ decays 
compared to the PQCD prediction relative to the corresponding $J/\psi$ decays.
\par
\hspace{0.4cm}
Recently BES has systematically studied the $\psi(2s)$ hadronic decays to VP,
VT and AP meson final states with 3.6 million produced $\psi(2s)$ events
collected from 1993 to 1995.  The number of $\psi(2s)$ events, 
$N_{\psi^\prime}$,
 are determined by three independent ways. (1)Direct determination.  (2)  
 $N_{\psi^\prime}$ is inferred from $J/\psi$ production in $\psi(2s) 
\rightarrow 
\pi^+\pi^- J/\psi$ decay where the $J/\psi$ production is inferred in the 
recoil from the $\pi^+\pi^-$ system. (3) $N_{\psi^\prime}$ is inferred from 
$J/\psi$ production in $\psi(2s) \rightarrow 
\pi^+\pi^- J/\psi$ decay where the $J/\psi$ is observed from its direct decay 
into $\mu^+\mu^-$ final states. These three methods give a same results within
error of 4\%. 
\par
\hspace{0.4cm}With this high statistics study, BES obtained intresting
results on VP and VT final states of $\psi(2s)$ decays in Table 1. Following
conclusions can be extracted:
\begin{enumerate}
\item For the  $\rho\pi$ and $K^{*\pm}K^{\mp}$ decay modes, BES set a new
upper 
   limits at 90\% confidence   level for the branching fractions of 
\begin{eqnarray*}
     B(\psi(2s) \rightarrow \rho\pi) < 2.9 \times 10^{-5}, \\
     B(\psi(2s) \rightarrow K^{*\pm}K^{\mp}) < 3.2 \times 10^{-5}.
\end{eqnarray*}
   These values are significantly lower than the corresponding upper limits 
   set by Mark II
   group[4]. Using the PDG values of branching fractions of $J/\psi$ decays
   to corresponding final states, BES set the limits on the ratios of branching
   fractions:
\begin{displaymath}
        Q_{\rho\pi} < 0.0023, \ \ \       Q_{K^{*\pm}K^{\mp}} < 0.0064.
\end{displaymath}
   These are more than a factor of 60 and 20 below the PQCD predictions,
   respectively.  Therefore, BES has confirmed and improved the previous
   observation of VP suppression of $\psi(2s)$ decays.
\item BES made the first measurement of the $\psi(2s)$ decay to
$K^{*0}\overline{K}^0$
final   state (VP mode).  The branching fraction of this channel is
\begin{displaymath}
   B(\psi(2s) \rightarrow K^{*0}\overline{K}^0) = (8.4 \pm 2.9) \times 10^{-5}.
\end{displaymath}
   Using the PDG value of branching fraction of $J/\psi$ decay yields the
   ratio of branching fractions
\begin{displaymath}
        Q_{K^{*0}\overline{K}^0} = 0.020 \pm 0.007.
\end{displaymath}
\item  There have been a number of theoretical attempts to explain the VP 
   suppression puzzle[7,8].  However, it seems none of them can explain the
   existing data.
\item  The $\psi(2s)$ decays into $2(\pi^+\pi^-)\pi^0$ and $\pi^+\pi^-K^+K^-$
   final states have been studied from fully reconstructed events.
    Three vector-tensor combinations,$\omega f_2$, $\rho a_2$ and
   $K^{*0}\overline{K}_2^{*0}$, are measured in $\psi(2s)$ decays for the first
   time.  The branching fractions are
\begin{eqnarray*}
     B(\psi(2s) \rightarrow \rho a_2)& = &(31 \pm 19) \times 10^{-5}, \\
     B(\psi(2s) \rightarrow \omega f_2)& < &15 \times 10^{-5},        \\
     B(\psi(2s) \rightarrow K^{*0}\overline{K}_2^{*0})& < &18 \times 10^{-5}.
\end{eqnarray*}
   Using the PDG values of branching fractions of $J/\psi$ decays to 
   corresponding final states, we obtained the ratios of branching fractios:
\begin{displaymath}
     Q_{\rho a_2} = 0.028 \pm 0.017,  \ \ \ 
     Q_{\omega f_2} < 0.035,          \ \ \
     Q_{K^{*0}\overline{K}_2^{*0}} < 0.028,
\end{displaymath}
   much lower than the prediction of PQCD.   It changes the long-time adopted
   picture that the anomaly in charmonium hadronic decays is only seen in
   vector-pseudoscalar final states.  Now the puzzle extends to the VT decay!
\item  The discovery of VT anomaly is theoretically even more puzzling.  The
   vector- pseudoscalar decays,$\rho\pi$,$K^{*\pm}K^{\mp}$ and 
   $K^{*0}\overline{K}^0$, are
   stronly suppressed and they are not allowed by the pertubative QCD theorem
   that total hadron helicity is conserved (HHC) in high-momentum-transfer
   exclusive processes[8].  However, a recent analysis [9] has shown that the
   vector-tensor decays,$\omega f_2$, $\rho a_2$ and 
   $K^{*0}\overline{K}_2^{*0}$,
   are allowed by the HHC theorem.  Hence their suppression poses new 
   challenges to the theory.
\end{enumerate}

\newpage
%\vspace{1cm}
\centerline{\bf Table 1.   Experimental Ratios of VP and VT modes}
\vspace{0.4cm}
\begin{center}

\begin{tabular}{|c|c|c|c|c|}
\hline
&Decay Mode  &B($\psi(2s)$) ($10^{-5}$)  & B($J/\psi$) ($10^{-3}$)  & Q (\%) \\
\hline
VP& $\rho\pi$            &$<2.9$          &$ 12.8 \pm 1.0 $ &$ <0.23 $       \\
  & $K^{*\pm}K^{\mp}$    &$<3.2$          &$  5.0 \pm 0.4$  & $<0.64$        \\
  & $K^{*0}\overline{K}^0$ &$ 8.4 \pm 2.9$  &$  4.2 \pm 0.4 $ &$  2.0 \pm 0.7$\\
   \hline
VT& $\omega f_2$       &$<15$           & $ 4.3 \pm 0.6 $ &$ <3.5 $        \\
  & $\rho a_2$         &$ 31 \pm 19  $  &$ 10.9 \pm 2.2 $ & $ 2.8 \pm 1.7$ \\
  &$ K^{*0}\overline{K}_2^{*0}$ &$<18$    & $ 6.7 \pm 2.6$  &$ <2.8$\\
  \hline
\end{tabular} 
\end{center}

\hspace{2.85cm} note : (1) Upper limits are at 90\% confidence level.
\par
\hspace{4cm} (2) $J/\psi$ data are from PDG
\par
\hspace{4cm} (3) $\psi(2s)$ data are from BES measurement
%\vspace{2cm}

\subsubsection{Branching fractions of $\psi(2s)$ decays to octet-baryon pairs}
\par
\hspace{0.4cm}In the context of flavor SU(3), a pure $c\overline{c}$ state is 
a flavor singlet and, in the limit of SU(3) flavor symmetry, the phase-space-
corrected reduced branching fractions to any baryon octet pair,
$\mid M_i \mid^2$,
\begin{displaymath}
\mid M_i \mid^2  =  \frac{B(\psi(2s) \rightarrow B_i\overline{B_i})}
 {\pi p^*/\sqrt{s}}
\end{displaymath}
($p^*$ is the momentum of the baryon in the $\psi(2s)$ rest frame), should be
the same for every octet baryon,$B_i$.  Deviations from this rule would
indicate a non- $c\overline{c}$ component of the charmonium wave function.
The reduced branching fractions for $J/\psi \rightarrow B_8\overline{B}_8$
decays are shown in Table 2. The SU(3) relation works reasonably well, although
there may be some preference for the $p\overline{p}$ mode.
\par
\hspace{1cm}This relation has not been tested for the $\psi(2s)$, where the
only relevant branching fraction that has been measured is $\psi(2s)
\rightarrow p\overline{p}$, and that with rather poor precision[10].
\par
\hspace{1cm}Here we report preliminary results of measurements of the branching
fractions for $\psi(2s) \rightarrow B_i\overline{B}_i$, where $B_i=p,\Lambda,
\Sigma^0,\Xi^-,\Delta^{++},\Sigma^{*-},\Xi^{*0}$ and $\Omega^-$, using a sample
of 3.6 million produced $\psi(2s)$ events. The measured branching fractions
are listed on Table 3, together with their ratios of branching fractions,
   Using the PDG values of branching fractions of $J/\psi$ decays to 
   corresponding final states.  It seems, They basicaly agree with the PQCD's
expectation. The reduced branching fractions derived from our measurements 
have been included in Table 2.  The results show a trend to smaller values
for the higher masses, showing some deviation from expectations based on
flavor SU(3) symmetry.  Higher precision measurements both for the $J/\psi$ 
and $\psi(2s)$ would clarify this problem. 

\vspace{1cm}
\centerline{\bf Table 2. Reduced branching fractions $\mid M_i \mid^2$ for
$J/\psi, \psi(2s) \rightarrow B_i\overline{B}_i$ \ \  ($10^{-4})$ }
\vspace{0.4cm}
\begin{center}
\begin{tabular}{|c|c|c|c|c|c|c|}
\hline

&$p\overline{p}$                 &$\Lambda\overline{\Lambda}$ 
&$\Sigma^0\overline{\Sigma}^0$   &$\Delta^{++}\overline{\Delta}^{--}$    
&$\Xi^-\overline{\Xi}^-$         &$\Sigma^{*-}\overline{\Sigma}^{*+}$ \\\hline
$\mid M_i \mid^2_{J/\psi}$ ($10^{-4}$) &$17.1 \pm 0.8$ &$12.4 \pm 1.3$ &
$12.6 \pm 1.7$
                                     &             &$10.9 \pm 2.4$ &          \\
$\mid M_i \mid^2_{\psi^\prime}$ ($10^{-4}$)  &$2.02 \pm 0.29 $&$1.69 \pm 0.28$
         &$0.78 \pm 0.40$ &$0.76 \pm 0.22$ &$0.76 \pm 0.27 $&$0.54 \pm 0.26$
         \\\hline 
\end{tabular} 
\end{center}

\vspace{2cm}
\centerline{\bf Table 3.   Experimental Ratios of $B_8\overline{B}_8$ modes}
\vspace{0.4cm}
\begin{center}
\begin{tabular}{|c|c|c|c|}
\hline
Decay Mode  &B($\psi(2s)$) ($10^{-5}$)  & B($J/\psi$)   ($10^{-3}$) & Q (\%)\\\hline

$p\overline{p}$                &$27.3 \pm 3.9$ & $2.14 \pm 0.10$  &
$12.8 \pm 1.9$\\
$\Lambda\overline{\Lambda}$    &$21.1 \pm 3.5$ &$ 1.35 \pm 0.14$  & $15.6
\pm 3.1$\\
$\Sigma^0\overline{\Sigma}^0$  &$ 9.4 \pm 4.8$ & $1.3  \pm 0.2 $  &
$7.2 \pm 3.9$\\
$\Delta^{++}\overline{\Delta}^{--}$ & $8.9 \pm 2.6$ &$ 1.10 \pm 0.29$ &
$8.1\pm 3.2$\\
$Xi^-\overline{\Xi}^-$        & $8.3 \pm 3.0$ & $0.9  \pm 0.2 $  &
$ 9.2 \pm 3.9$\\
$\Sigma^{*-}\overline{\Sigma}^{*+}$   & $5.6 \pm 2.7$ & $1.03 \pm 0.13$ &
$5.4\pm 2.7$\\
$\Xi^{*0}\overline{\Xi}^{*0}$       &$<7.5 $        &               & 
\\
$\Omega^-\overline{\Omega}^+$       &$<8.3$         &               \\\hline
\end{tabular} 
\end{center}

\section{The measurements of $\chi_{c0}$ decay width}

\hspace{1cm}The charmonium p-wave triplet states $\chi_{cJ}$ (J=0,1,2) were
found soon after the $J/\psi$ and $\psi(2s)$ discovery in 1970's, but most of
their decay parameters were measured before 1980's.  Recently E760 experiment
[11] at Fermilab measured the total widths and $p\overline{p}$ partial widths
for $\chi_{c1}$ and $\chi_{c2}$, but for $\chi_{c0}$ the scan has 
not been done yet. The measured value of $\chi_{c0}$ decay width,
$\Gamma_{\chi c0}=13.5\pm3.3 \pm4.2 MeV$, are from
Crystal Ball experiment [12], which is the weighted average of two values :
13-21 Mev from $\psi(2s) \rightarrow \gamma X$ study and $8.8\pm1.3\pm1.5 MeV$
from $\psi(2s) \rightarrow \gamma \pi^0 \pi^0$. 
\par
\hspace{1cm}Using 3.6 million produced $\psi(2s)$ events we select 
$\gamma \pi^+ \pi^-$ and $\gamma K^+K^-$ events by proper selection criteria,
 and then using kinematic fit to reduce backgrounds. The obtained $\pi^+\pi^-$ 
and $K^+K^-$ invariant mass spectra
are shown in Fig. 1, which shows two clear peaks corresponding to  $\chi_{c0}$
and  $\chi_{c2}$, respectively.  Parity conservation law forbids  $\chi_{c1}$ 
and  $\eta_c(2s)$ production in the studied final states, therefore, there is
no distortion of the $\chi_{c0}$ and  $\chi_{c2}$ spectra due to contaminations
from other resonances.  The mass resolution of $\chi_{c2}$ obtained from our
Monte Carlo simulation is calibrated by fitting our measured peak with
known accurate $\chi_{c2}$ width by E760 experiment.  Hence we can infer the
reliable mass resolution at $\chi_{c0}$ mass region.
\par
\hspace{1cm}However, there exist cross contamination in the invariant mass
distribution between $\pi^+\pi^-$ and $K^+K^-$ channels. Theory and experiments
have shown[13] that $\chi_{cJ}$ is generated via pure E1 transition of 
$\psi(2s)$ and $\chi_{cJ} \rightarrow 0^-0^-$ meson pairs has only one 
independent helicity amplitude.  The Monte Carlo simulation was done based on
the generator with the mechanism stated above to determine the detection
efficiencies for both channels and the cross contamination probabilities
betweem them.  After this correction, fitting the invariant mass spectra  
with the fixed $\chi_{c2}$ width 2.00 MeV (from PDG) yields following results:
\begin{displaymath}
     \Gamma_{\chi_{c0}} = 15.0\pm ^{3.3}_{2.8} MeV,
\end{displaymath}
where the error includes the statistical and the systematic.  This result is in
agreement with the world average value, but with higher precision.  The ratio
of our measured  $\Gamma_{\chi_{c0}}$ to  $\Gamma_{\chi_{c2}}$ (PDG) is
$7.5 \pm ^{1.8}_{1.6}$, which agrees with W.Kwong's theoretical prediction[14],
while it has large discrepancy with the calculation by G.T.Bodwin[15]. 
\par
\hspace{1cm}We have also obtained the partial widths of $\chi_{c0}$,$\chi_{c2}$
decays to $\pi^+\pi^-$,$K^+K^-$ and $p\overline{p}$ listed in Table 4.  it can
be seen that the BES measurements are more precise than PDG values. For partial
widths of $\chi_{c0} \rightarrow \pi^+\pi^-,K^+K^-$, BES measurements deviate
from PDG values significantly, while for other partial widths they coinside
in one standard deviation.  From the branching fractions listed in Table 4, we
obtained following ratios: 

\begin{eqnarray*}
\frac{B(\chi_{c0} \rightarrow \pi^+\pi^-)}{B(\chi_{c0} \rightarrow K^+K^-)}
&=& 1.24 \pm 0.13, \\
\frac{B(\chi_{c2} \rightarrow \pi^+\pi^-)}{B(\chi_{c2} \rightarrow K^+K^-)}
&=& 2.95 \pm 1.18, \\
\frac{B(\chi_{c0}\rightarrow\pi^+\pi^-)}{B(\chi_{c2}\rightarrow\pi^+\pi^-)}
&=& 2.81 \pm 0.63, \\
\frac{B(\chi_{c0} \rightarrow K^+K^-)}{B(\chi_{c2} \rightarrow K^+K^-)}
&=& 6.6 \pm 2.7.
\end{eqnarray*}

Do these ratios mean that there exist asymmetry in the decays of  
$\chi_{c0},\chi_{c2} \rightarrow \pi^+\pi^-, K^+K^-$? This is an open question
and needs more precise data.

\vspace{1cm}
\centerline{\bf Table 4. Partial widths for $\chi_{c0}$ and $\chi_{c2}$ decays
to $\pi^+\pi^-$, $K^+K^-$ and $p\overline{p}$ ($10^{-4}$)  }
\vspace{0.4cm}
\begin{center}
\begin{tabular}{|c|c|c|c|c|}
\hline
            &    &$\pi^+\pi^-$    &$K^+K^-$        &$p\overline{p}$ \\\hline
$\chi_{c0}$ &BES &$42.7 \pm 6.4$ &$34.4 \pm 5.1$ &$1.45 \pm 0.50$         \\
            &PDG &$75   \pm 21 $ &$71   \pm24  $ &$<9.0 $                 \\\hline
$\chi_{c2}$ &BES &$15.2 \pm 3.4$ &$ 5.2 \pm 2.1$ &$0.96 \pm 0.54$         \\
            &PDG &$19   \pm 10 $ & $15  \pm 11 $ &$1.00 \pm 0.10$         \\\hline
\end{tabular} 
\end{center}

\section{Summary}
\hspace{1cm}With the largest  $\psi(2s)$ events sample in the world, BES is 
able to study its decays more precisely and to extend the investigation to
other charmonium states, such as $\chi_c$, $\eta_c$, etc..   Significant
improvements have been reached in many decay channels by BES measurements.
\begin{enumerate}
\item  The branching fraction of $\psi(2s) \rightarrow \tau^+\tau^-$ has been
   determined for the first time to be $(3.5 \pm 0.5 \pm 0.6) \times 10^{-3}$. 
      This value conserves the $e-\mu-\tau$ universality.
\item Severe suppression is observed in
      $\psi(2s)$ decays into a vector and a pseudoscalar mesons, 
      $\rho\pi$, $K^{*\pm}\overline{K}^{\mp}$, and $K^{*0}\overline{K}^0$.
\item Sgnificant suppression is seen in $\psi(2s)$ decays into vector-tensor 
      final states, $\omega f_2$, $\rho a_2$ and $K^{*0}\overline{K}_2^{*0}$.
\item existing theoretical models can not explain observed suppression.
\item The total decay width for $\chi_0$ and the patial decay widths of  
      $\pi^+\pi^-$,  $K^+K^-$ and $p\overline{p}$ for $\chi_0$ and $\chi_2$ 
      have been measured with improved accuracies.  The open question is if
      there exists asymmetry in the decays of  
      $\chi_{c0},\chi_{c2} \rightarrow \pi^+\pi^-, K^+K^-$.
\end{enumerate}

It seems that, the present situation of charmonium physics is still very 
mystery. The big challenge both in theoretical and experimental aspects are put
in front of physicists on the way going to real understanding for the nature.

\section*{References}
\begin{enumerate}

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\end{enumerate}

\end{document}
