LIGHT MESONS FROM CHARM \\ MESON DECAYS IN FNAL E791
B. T. MEADOWS \footnote{Representing the E791 collaboration.}
An analysis of the Dalitz plots for the decays $D^+\to\Km\pip\pip$ and $D^+\to\pim\pip\pip$ indicates that structure with significant phase variation is required in the $s$-wave $\Km\pip$ and $\pim\pip$ systems in the region below 1 GeV/c$^2$ effective mass. A constant, non resonant ``contact" term, together with a simple $s$-wave Breit Wigner amplitude with $M_{\z}=797\pm 19\pm 43, \Gamma_{\z}= 175\pm 12\pm 12$~MeV/c$^2$ for the $\Km\pip$ system and $M_{\z}=478^{+24}_{-23}\pm 17,~\Gamma_{\z}=324^{+42}_{-40}\pm 21$~MeV/c$^2$ for the $\pim\pip$ system provide good fits to the data in this region.
babar.tex
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% **************************************************************************

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d3_table.tex
\begin{tabular}{|ccccccc|}
\hline
\\[-12pt]
$D^+\to$
& $\Km\pip\pip$   & $\kappa\pi$       & $K_1(890)\pi$
& $K_{0}(1430)\pi$
                  & $K_2(1430)\pi$    & $K_1(1688)\pi$
\\[1pt] \hline \\[-12pt]
I
& $90.0\pm 2.6$   & -                 & $13.8\pm 0.5$ 
& $30.6\pm 1.6$   & $0.4\pm 0.1$      & $3.2\pm 0.3$
\\[0pt]
%B
%& $89.5\pm 16.1$  & -                 & $12.1\pm 3.3$
%& $28.7\pm 10.2$  & $0.5\pm 0.3$      & $3.7\pm 1.9$
%\\[0pt]
II
& $13.0\pm 5.8$   & $47.8\pm 12.1$    & $12.3\pm 1.0$
& $12.5\pm 1.4$   & $0.5\pm 0.1$      & $2.5\pm 0.7$
\\[-3pt]
& $\pm 4.4$       & $\pm 5.3$         & $\pm 0.9$
& $\pm 0.5$       & $\pm 0.2$         & $\pm 0.3$
\\[1pt] \hline \\[-12pt]
$D^+\to$
& $\pim\pip\pip$   & $\sigma\pi$      & $\rho(770)\pi$
& $f_{0}(980)\pi$ & $f_2(1270)\pi$   & $\rho(1450)\pi$
\\[1pt] \hline \\[-12pt]
III
& $38.6\pm 1.4$    & -                & $20.8\pm 2.3$ 
& $ 7.4\pm 4.3$    & $6.3\pm 3.3$     & $22.6\pm 2.1$
\\[0pt]
IV
& $ 7.8\pm 6.0$    & $46.3\pm 9.0$    & $33.6\pm 3.2$
& $ 6.2\pm 1.3$    & $19.4\pm 2.5$    & $ 0.7\pm 0.7$
\\[-3pt]
& $\pm 2.7$        & $\pm 2.1$        & $\pm 2.2$
& $\pm 0.4$        & $\pm 0.4$        & $\pm 0.3$
\\[-1pt] \hline
\end{tabular}

mytex.tex
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paper.tex


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%                  MORIOND.TEX     2-Feb-1995                        %
% This latex file rewritten from various sources for use in the      %
% preparation of the standard proceedings Volume, latest version     %
% for the Neutrino'96 Helsinki conference proceedings                %
% by Susan Hezlet with acknowledgments to Lukas Nellen.              %
% Some changes are due to David Cassel.                              %
%                                                                    %
% Updated to LaTeX2e and adapted to Moriond 2001 conditions          %
%                     by F.Montanet 24/04/2001                       %
%====================================================================%

\documentclass[11pt]{article}
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\bibliographystyle{unsrt}
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% first citation.

% 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\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\EPJ{{\em Eur. Phys. J. direct}}

% Some other macros used in the sample text
\def\st{\scriptstyle}
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\def\epp{\epsilon^{\prime}}
\def\vep{\varepsilon}
\def\ra{\rightarrow}
\def\ppg{\pi^+\pi^-\gamma}
\def\vp{{\bf p}}
\def\ko{K^0}
\def\kb{\bar{K^0}}
\def\al{\alpha}
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\def\be{\begin{equation}}
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\input mytex.tex
\input babar.tex
%
\begin{document}
%
\newlength{\figwidth}
\newlength{\figheight}
%
\vspace*{4cm}
\title{LIGHT MESONS FROM CHARM \\ MESON DECAYS IN FNAL E791}

\author{ B. T. MEADOWS
\footnote{Representing the E791 collaboration.}
}
\address{Department of Physics \\ University of Cincinnati
\footnote{Supported by NSF grant 9901568.}
\\
Cincinnati, OH, USA}

\maketitle\abstracts{
An analysis of the Dalitz plots for the decays $D^+\to\Km\pip\pip$ and
$D^+\to\pim\pip\pip$ indicates that structure with significant
phase variation is required in the $s$-wave $\Km\pip$ and $\pim\pip$
systems in the region below 1 GeV/c$^2$ effective mass.  A constant,
non resonant ``contact" term, together with a simple $s$-wave Breit
Wigner amplitude with
$M_{\z}=797\pm 19\pm 43, \Gamma_{\z}= 175\pm 12\pm 12$~MeV/c$^2$ for the
$\Km\pip$ system and
$M_{\z}=478^{+24}_{-23}\pm 17,~\Gamma_{\z}=324^{+42}_{-40}\pm 21$~MeV/c$^2$
for the $\pim\pip$ system provide good fits to the data in this region.}

\section{Introduction}
%
% The scalar meson spectrum is only poorly understood.  Fifteen scalar states
% - $\fz(600)$, $\fz(980)$, $\az(980)$, $\fz(1370)$, $\az(1440)$, $\fz(1500)$,
% $\f_{0}(1710)$ and $K_{0}(1430)$ - are listed in the Particle Data Group
% listings \cite{pdg} (PDG).
% Only one strange scalar meson is established to exist, allowing for only one
% nonet.  Though it is likely that glueball states could mix with scalar
% mesons, the lowest lying glueball is thought to have a mass of about 1700
% MeV/c$^2$ leaving interpretation of most of these states as gluonic hybrids
% doubtful.  The existence of the $\fz(600)$ has long been established, but
% its pole position has been difficult to pin down due to interference with
% $s$-wave background in $\pi\pi$, $K\bar{K}$ systems in which it has been
% mostly studied.
%
Decays of $D$ mesons to three pseudo scalar mesons can produce intermediate,
two meson systems with natural parity.  Kinematics and angular momentum
barrier factors generally favour scalar ($J^P=0^+$) over vector $1^-$ or
tensor $2^+$ systems.  Analysis of these decays can therefore provide new
information on the poorly understood scalar meson system.

In most instances, $D$ decays appear to proceed through quasi two body
channels.  In the cases of $D^+$ decays
\footnote{Except where indicated otherwise, charge conjugate systems are
implied in this paper.}
to $\pim\pip\pip$ and to $\Km\pip\pip$ however, intermediate states
found in the Particle Data Group listings \cite{pdg} (PDG) have been
found to contribute only partially to the decays, with three body modes
apparently dominant \cite{e691,e687:kpipi}.  We report here on analyses
\cite{e791:d3pi,e791:kpipi} of these decays using the largest samples so
far examined.


\section{Fermilab Experiment E791}

In this experiment \cite{e791:exp} $2\times 10^{10}$ charm enhanced
interactions between 500 GeV/c $\pim$ mesons and thin foil targets
(four $C$, one $Pt$) are recorded \cite{e791:odf}.  Foils are spaced so
that decays of $D$ mesons produced in them occur predominantly
between them.  Silicon strip detectors measure
$D$ decay lengths (mean $\sim$5~mm) with a typical precision of
350 $\mu$m.
Charged particle momenta are measured with two dipole magnets and
drift chambers and two threshold gas Cherenkov detectors provide
$K/\pi/p$ separation in the 6-60~GeV/c momentum range.


%\section{Data Samples}
%
Events with one negative and two positive charged tracks making a
good vertex, well separated from any foil and from
the primary interaction point, are selected for further analysis.
The resultant momentum is required to point back to within 
40~$\mu$m of the primary vertex. For the $\Km\pip\pip$ sample the 
$\Km$ is required to have momentum $6$~GeV/c$<|\vec p_K|<40$~GeV/c
and to be identified by the Cherenkov detectors.
Other cuts are also made to reduce contamination from
tracks that are really associated with the primary vertex.
%
With these selection criteria, the major sources of background are
mostly misidentified (or incomplete) charm decays, with a small,
``combinatorial" contribution from false secondary vertices.  
% For
% the $\Km\pip\pip$ decay charm backgrounds include
% $\Dz\to\Km\pim\pip\pip$, $D_s^+\to \Kstbar\Kp$, $D_s\to\phi\pip$
% (mostly removed by cutting on the $\phi\to\Km\Kp$ hypothesis for
% a $\Km\pip$ combination).  For the three pion channel major charm
% backgrounds are from $\Dz\to\Km\pim\pip\pip$, $D_s^+\to\eta'~
% (\to\pip\pim\gamma)\pip$, $D^{\z}\to\Km\pip$ (with an extra,
% incorrectly assigned $\pip$).
Yields of 15,090 $\Km\pip\pip$
(6\% background) and 1,686 $\pim\pip\pip$ (28\% background) remain
in the signal regions.


\section{Isobar Analysis of $D$ Decay to Three Pseudo-Scalars}
\label{sec:isobar}

Decays of $D$ mesons to three pseudo scalars $i,~j,~k$
can be described approximately as a sum of isobar amplitudes, each 
corresponding to a quasi two body decay $D\to R(\to i~j)~k$.
Each amplitude must satisfy Lorentz invariance and conserve total spin 
and has the form
%
 \begin{eqnarray*}
   \Ampl_{\ssc R}(s_{ij}, s_{ik}) &=&
          F_{\ssc D}(q,r_{\ssc D})
          F_{\ssc R}(p,r_{\ssc R})
          \times BW_{\ssc R}(s_{ij})
          \times~(-2)^J |\vec p|^J |\vec q|^J P_J(\cos\theta)
 \end{eqnarray*}
%
where $\vec p, \vec q$ are momenta of $i$ and $k$ respectively in 
the $(ij)$ rest frame and $\cos\theta=\hat p\cdot\hat q$.
Form factors $F_{\ssc D}$ ($F_{\ssc R}$) for $D$ ($R$) are parametrized 
in terms of  effective radii $R_{\ssc D}$ ($R_{\ssc R}$).  A Breit Wigner 
propagator
$BW_{\ssc R}=\left[s_{\ssc R} - s_{ij} -
               i\sqrt{s_{\ssc R}}\;\Gamma(s_{ij}) \right]^{-1}$
describes the resonance $R$ with spin $J$, mass $\sqrt{s_{\ssc R}}$.
Suffix $R$ denotes a quantity evaluated at $s_{ij}=s_{\ssc R}$.

A decay is kinematically specified by coordinates $(s_{ij}, s_{ik})$
%(squared invariant mass combinations)
on a Dalitz plot and by the
three body mass $M_{ijk}$ whose distribution about the $D$ mass $m_D$
due to resolution is $G(M_{ijk})$, determined from the data.
The signal distribution of decays is
  \[ {\cal P}_{\ssc S}(s_{ij}, s_{ik}, M_{ijk}) ~=~G(M_{ijk})\times
     \left|\, a_{\ssc NR}e^{i\delta_{\ssc NR}}~+~\sum_{\ssc R} a_{\ssc R}
     e^{i\delta_{\ssc R}}\Ampl_{\ssc R}(s_{ij}, s_{ik})\, \right|^2 \]
in which three body decays (NR) are described by a constant,
``contact" amplitude $a_{\ssc NR}e^{i\delta_{\ssc NR}}$.

The distribution ${\cal P}_{\ssc B}(s_{ij}, s_{ik}, M_{ijk})$ of
backgrounds is modelled using events from side bands in $M_{ijk}$ for
combinatorial, and from MC simulations for broken charm sources.  The
efficiency $\epsilon(s_{ij},s_{ik})$ for observing decays is
determined from MC simulations.

Complex coefficients $ae^{i\delta}$ and resonance parameters are 
determined from fits to a linear combination of 
$\epsilon{\cal P}_{\ssc S}$ and ${\cal P}_{\ssc B}$ in the
correct proportions.  The fraction of $D$ decay to an isobar $R$ is
$f_{\ssc R} = G(M_{ijk})\int |{\cal A}_{\ssc R}|^2 ds_{ij}ds_{ik} /
              \int{\cal P}_{\ssc S} ds_{ij}ds_{ik}$
evaluated at $M_{ijk}=m_{\ssc D}$.


\section{The $\Km\pip\pip$ Channel.}

\begin{figure}[ht]
%
 \begin{minipage}[t]{0.48\textwidth}
  \setlength{\figwidth}{0.90\textwidth}
  \setlength{\figheight}{0.80\textwidth}
  \centerline{%
  \epsfig{file=Figures/kpipi_dp.eps,
       height=0.95\figheight,
       width=0.95\figwidth,angle=0}}
  \large
  \vskip-0.9\figheight\hskip0.30\figwidth{\bf (a)}
  \par\vspace{0pt}
 \end{minipage}
 %
 \hspace{0.00\textwidth}
 %
 \begin{minipage}[t]{0.48\textwidth}
  \setlength{\figwidth}{0.90\textwidth}
  \setlength{\figheight}{0.80\textwidth}
  \centerline{%
  \epsfig{file=Figures/badfit_kpipi.eps,
          width=0.95\figwidth,
          height=\figheight,
          angle=0}}
  \large
  \vskip-0.30\figheight\hskip.86\figwidth
  \Red{$\mathbf\downarrow$}\hskip-5.5pt
  \Red{$\mathbf\downarrow$}
  \vskip-0.58\figheight\hskip0.30\figwidth
  \Red{$\mathbf\searrow$}\hskip-11.5pt
  \Red{$\mathbf\searrow$}
  \vskip-0.22\figheight\hskip0.87\figwidth
  \Red{$\mathbf\searrow$}\hskip-11.5pt
  \Red{$\mathbf\searrow$}
  \vskip-.11\figheight\hskip0.28\figwidth{\bf (b)}
  \vskip0.49\figheight\hskip0.28\figwidth{\bf (c)}
  \par\vspace{0pt}
 \end{minipage}
 %
 \caption{(a) Dalitz plot for $D^+\to\Km\pip\pip$ decays.
  Projections for (b) smaller and (c) larger
  $K\pi$ effective mass for data (crosses)
  and fit (line) to model I described in
  the text.  Arrows indicate regions where the fit is worst.
 \label{fig:kpipi}}
 \vskip-6pt
\end{figure}
%
The Dalitz plot in figure \ref{fig:kpipi}(a) shows clear bands in
the $\bar{K}_{1}(890)$ regions with an asymmetric structure
indicative of interference with a significant, underlying
$s$-wave.  An accumulation of events near 2~(GeV/c$^2)^2$
indicates contributions from $\bar{K}_{\z}(1430)$ or
$\bar{K}_{2}(1430)$.  A fit is made including isobar amplitudes 
for these resonances and the $\bar{K}_{1}(1688)$, each with
mass and width fixed at their PDG values.  Results
are shown in table \ref{tab:d3} (model I) and compared with the
$\Km\pip$ mass projections in figures \ref{fig:kpipi}(b) and (c).
As in previous analyses \cite{e691,e687:kpipi} using this model, a
large NR component is required ($\sim 90$\%) and the sum of all
contributions is $\sim 140$\% indicating much destructive
interference.
%
\begin{table}[ht]
\caption{Resonant fractions $f$ for $D^+\to\Km\pip\pip$,
and $\pim\pip\pip$.  Models I-IV are described in the text.
\label{tab:d3}}
\vspace{0.4cm}
\begin{center}
\input{d3_table.tex}
\vskip-6pt
\end{center}
\end{table}
%
The fit is poor with a $\chi^2$, found by comparing predictions of
model I with data in equal square bins in the Dalitz plot, of 167
for 63 degrees of freedom $\nu$.  Major discrepancies are at
low $\Km\pip$ masses, and the corresponding high mass reflection, and
can be seen in earlier data for both this channel \cite{e687:kpipi}
and for $D^{\z}\to\Km\pip\piz$ \cite{cleokpipi}.  However the large
E791 sample underlines their significance, and demands that a better
model be found.

First, the radii $R_{\ssc D}$, $R_{\ssc R}$ and the mass and width of
$K_{0}(1430)$ are allowed to float \cite{wmd}.  This produces little
improvement.  Next, a further scalar amplitude ``$\kappa"$ having a
Breit Wigner form similar to $K_{0}(1430)$ is added (model II in
Table \ref{tab:d3}).  This does provide an excellent description of
the data with $\chi^2/\nu=46/63$.  The $\kappa$ mode is dominant while
the NR component is consistent with zero.  The sum of fractions is
$\sim 86$\%.  The $\kappa$ mass and width, determined from the fit,
are $M_{\z}=797\pm 19\pm 43$ and $\Gamma_{\z}= 175\pm 12\pm 12$~MeV/c$^2$.
In this model, however, the $K_{0}(1430)$ mass and width are found to be
$1459\pm 7\pm 12$~MeV/c$^2$ and $175\pm 12\pm 12$~MeV/c$^2$ respectively,
differing somewhat from the values from LASS \cite{wmd}.

The $s$-wave BW form used for the $\kappa$ in model II appears to be
important.  Variations in this, or in form factors for $\kappa$ and NR
terms, are found to affect principally the amounts of $\kappa$ and NR,
but to have relatively small effects on $\kappa$ mass and width
parameters.  Replacing the complex BW in model II by its absolute
magnitude (a ``$\kappa$" mass enhancement, but no phase variation)
results in unphysically large $\kappa$ and NR fractions.  A vector form for
$\kappa$ converges with mass $\sim 1100$~MeV/c$^2$ and negligible fraction.
A tensor $\kappa$ fit fails to converge.


\section{$D^+\to\pim\pip\pip$ Decays.}
%
Figure \ref{fig:3pi}(a) is the Dalitz plot for these decays \cite{e791:d3pi}.
Table \ref{tab:d3} shows results for model III in which only resonances from
the PDG are included.  The fit is poor ($\chi^2/\nu=1.5$), especially in the
low mass $\pim\pip$ system as seen in figure \ref{fig:3pi}(b).  The
contribution from $\rho(1450)$ is larger than that from $\rho(770)$ -
a somewhat unlikely result.  As observed in the previous analysis
\cite{e687:d3pi} of this channel with a similar model, the NR mode dominates.
%
\begin{figure}[ht]
%
 \begin{minipage}[b]{0.38\textwidth}
  \setlength{\figwidth}{0.75\textwidth}
  \setlength{\figheight}{0.75\textwidth}
  \centerline{%
  \epsfig{file=Figures/dp2_d3pi.eps,
          width=\figwidth,
          height=\figheight,
          angle=0}}
  \large
  \vskip-0.85\figheight\hskip0.85\figwidth{\bf (a)}
  \vskip0.63\figheight
  \par\vspace{0pt}
 \end{minipage}
 %
 \hspace{0.00\textwidth}
 %
 \begin{minipage}[b]{0.57\textwidth}
  \setlength{\figwidth}{0.75\textwidth}
  \setlength{\figheight}{0.45\textwidth}
  \centerline{%
  \epsfig{file=Figures/badfit_d3pi.eps,
          width=\figwidth,
          height=\figheight,
          angle=0}}
  \large
  \vskip-.85\figheight\hskip1.00\figwidth{\bf (b)}
  \vskip0.72\figheight
  \par\vspace{0pt}
 \end{minipage}
 %
 \caption{(a) Dalitz plot for $D^+\to\pim\pip\pip$ decays.
  (b) Projection of $\pim\pip$ effective mass.  Data
  (points with errors) and predictions (solid line) from model III
  described in the text indicate poor agreement at low mass.
 \label{fig:3pi}}
\end{figure}
%

Adding a scalar amplitude ($\sigma$, similar to the $\kappa$ in
model II) results in a superior fit ($\chi^2/\nu=0.9$).  Results for this
(model IV) are in table \ref{tab:d3}.  Mass and width for $\sigma$ are found
to be $M_{\z}=478^{+24}_{-23}\pm 17$ and
$\Gamma_{\z}=324^{+42}_{-40}\pm 21$~MeV/c$^2$.
Both NR and $\rho(1450)\pi$ contributions are insignificant, and the
$\sigma\pi$ amplitude is dominant.
%
As for the $\kappa$, the $s$-wave BW form seems to be the best model
of those applied to these data.


\section{Conclusions.}

We conclude that the $s$-wave $\Km\pip$ system from decay of $D^+$
to $\Km\pip\pip$ has amplitude and phase variation consistent with a
sum of NR, $K_{0}(1430)$ and scalar $\kappa$ terms.  Similarly, the
$s$-wave $\pim\pip$ system from decay of $D^+\to\pim\pip\pip$
has amplitude and phase variation consistent with a sum of NR,
$f_{0}(980)$ and scalar $\sigma$ terms.  Though this hints at the
existence of scalar $\kappa$ and $\sigma$ resonances, use of Breit
Wigner functions to describe such broad states near threshold may not be
appropriate, and other interpretations of the data may be possible.


\section*{References}
\begin{thebibliography}{99}

\bibitem{pdg}K. Hagiwara et al., \Journal{\PRD}{66}{010001}{2002}.

\bibitem{e691}E691 collaboration, J. C. Anjos et al.,
 \Journal{\PRD}{48}{56}{1993}.

\bibitem{e687:kpipi}E687 collaboration, P. L. Frabetti et al.,
 \Journal{\PLB}{331}{217}{1994}.

\bibitem{e791:d3pi}E791 collaboration, E. M. Aitala et al.,
 \Journal{\PRL}{86}{770}{2000}.

\bibitem{e791:kpipi}E791 collaboration, E. M. Aitala et al.,
 {\em accepted by Phys. Rev. Letters},  hep-ex/0204018.

\bibitem{e791:exp}E791 collaboration, E. M. Aitala et al.,
 \Journal{\EPJ}{C4}{1}{1999}.

\bibitem{e791:odf}S. Amato et al.,
 \Journal{\NIM}{A324}{535}{1993}; S. Bracker et al., hep-ex/9511009.

\bibitem{cleokpipi}CLEO collaboration, S. Kopp et al.,
 \Journal{\PRD}{63}{092001}{2001}.

\bibitem{wmd}W. M. Dunwoodie (for LASS collaboration), {\em private
 communication.}  A recent re-fit to $I=1/2~s$-wave $K\pi$ elastic
 scattering data below $K\eta'$ threshold yields
 $M=1435\pm 5,~\Gamma=279\pm 40$~MeV/c$^2$
 compared to PDG values $1412\pm 6$ and $294\pm 23$~MeV/c$^2$
 respectively.

\bibitem{e687:d3pi}E687 collaboration, P. L. Frabetti et al.,
 \Journal{\PLB}{407}{79}{1997}.

\end{thebibliography}

\end{document}

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% End of moriond.tex  %
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hep-ex0208049.extracted_bib
\begin{thebibliography}{99}

\bibitem{pdg}K. Hagiwara et al., \Journal{\PRD}{66}{010001}{2002}.

\bibitem{e691}E691 collaboration, J. C. Anjos et al.,
 \Journal{\PRD}{48}{56}{1993}.

\bibitem{e687:kpipi}E687 collaboration, P. L. Frabetti et al.,
 \Journal{\PLB}{331}{217}{1994}.

\bibitem{e791:d3pi}E791 collaboration, E. M. Aitala et al.,
 \Journal{\PRL}{86}{770}{2000}.

\bibitem{e791:kpipi}E791 collaboration, E. M. Aitala et al.,
 {\em accepted by Phys. Rev. Letters},  hep-ex/0204018.

\bibitem{e791:exp}E791 collaboration, E. M. Aitala et al.,
 \Journal{\EPJ}{C4}{1}{1999}.

\bibitem{e791:odf}S. Amato et al.,
 \Journal{\NIM}{A324}{535}{1993}; S. Bracker et al., hep-ex/9511009.

\bibitem{cleokpipi}CLEO collaboration, S. Kopp et al.,
 \Journal{\PRD}{63}{092001}{2001}.

\bibitem{wmd}W. M. Dunwoodie (for LASS collaboration), {\em private
 communication.}  A recent re-fit to $I=1/2~s$-wave $K\pi$ elastic
 scattering data below $K\eta'$ threshold yields
 $M=1435\pm 5,~\Gamma=279\pm 40$~MeV/c$^2$
 compared to PDG values $1412\pm 6$ and $294\pm 23$~MeV/c$^2$
 respectively.

\bibitem{e687:d3pi}E687 collaboration, P. L. Frabetti et al.,
 \Journal{\PLB}{407}{79}{1997}.

\end{thebibliography}