% particle data information automatically produced from the herwig database
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\title{\boldmath{ $\eta'$}\ \ \ \ \ \ \ $*****$}
\maketitle
The $\eta'$ is the heavier of the isospin singlet mesons contaning light quarks from the $1^1S_0$ multiplet. The decay modes and properties are taken from \cite{Yao:2006px}. There are minor modifications to some of the branching ratios to ensure the branching ratios sum exactly to one. The $\eta'$ is allowed to be off-shell by ten times the width.
The $\eta'$ has mass $957.78$~MeV and is unstable. The $\eta'$ has spin $0$, charge $0$ and is colour neutral.
 The $\eta'$ is a meson and is from the $1^1S_0$ multiplet.The $\eta'$ has width $0.203$~MeV. The lower limit on the mass of the particle is $2.03$~MeV and the upper limit is $2.03$~MeV. These are the deviations from the on-shell value. The branching ratios are fixed.
The properties of the particle and its antiparticle are taken to be charge-conjugate to each other.
 The PDG code is 331.
\setlongtables
\begin{longtable}[t]{|c|c|c|p{1in}|p{2.5in}|c|}
\hline
Branching & Rating & On/ & Outgoing  & Description & Decayer  \\ 
Ratio     &                                 & Off & Particles &             &         \\ 
\hline
\endhead
\caption{The decay modes of the $\eta'$ (continues).}
\endfoot
\caption{The decay modes of the $\eta'$.}
\endlastfoot
\label{tab:331decaymodes}
0.444682 & $*****$ & on & $ \pi^+, \pi^-, \eta $  & Decay of the $\eta'$ to two pions and the $\eta$ with branching ratio taken from \cite{Yao:2006px} with minor changes to ensure the branching ratios sum to one.   & Herwig::EtaPiPiPi::Etapipipi \\ 
\hline
0.293790 & $*****$ & on & $ \pi^+, \pi^-, \gamma $  & Decay of the $\eta'$ to two pions and a photon with branching ratio taken from \cite{Yao:2006px}with minor changes to ensure the branching ratios sum to one.   & Herwig::EtaPiPiGamma::Etapipigamma \\ 
\hline
0.207852 & $*****$ & on & $ \pi^0, \pi^0, \eta $  & Decay of the $\eta'$ to two pions and the $\eta$ using the branching ration from \cite{Yao:2006px} with minor changes to ensure the branching ratios sum to one.   & Herwig::EtaPiPiPi::Etapipipi \\ 
\hline
0.030300 & $*****$ & on & $ \omega, \gamma $  & Decay of the $\eta'$ to $\omega$ and two pions using the branching ratio from \cite{Yao:2006px}.   & Herwig::PScalarVectorVector::PVV \\ 
\hline
0.021200 & $*****$ & on & $ \gamma, \gamma $  & The decay of the $\eta'$ to two photons with branching ratio taken from \cite{Yao:2006px}.   & Herwig::PScalarVectorVector::PVV \\ 
\hline
0.001550 & $****$ & on & $ \pi^0, \pi^0, \pi^0 $  & Decay of the $\eta'$ to three pions with branching ratio taken frmo \cite{Yao:2006px}.   & Herwig::EtaPiPiPi::Etapipipi \\ 
\hline
0.000522 & $**$ & on & $ e^-, e^+, \gamma $  & The decay of $\eta'$ to an electron-positron pair and a photon. This mode has not been observed. The branching ratio was calculated using the decayer and normalised using the muon mode. The branching ratio is below the experimental limit on the mode.   & Herwig::PScalarVectorFermions::PVff \\ 
\hline
0.000104 & $****$ & on & $ \mu^-, \mu^+, \gamma $  & Decay of $\eta'$ to a muon-antimuon pair and a photon with branching ratio taken from \cite{Yao:2006px}.   & Herwig::PScalarVectorFermions::PVff \\ 
\hline
\end{longtable}The $\eta'$ decay modes are given in Table~\ref{tab:331decaymodes} and the total branching ratio is $1$.


The mass generator is \verb|eta'mass| for the $\eta'$.
The width generator is \verb|eta'width| for the $\eta'$.

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 The particle was checked by Peter Richardson at 21:15:20 on the 20th of October 2007. The most recently changed decay mode was modified at 12:58:57 on the 2nd of August 2007. The particle data was last modified at 12:59:26 on the 2nd of August 2007.

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