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\title{\boldmath{ $f_2(1270)$}\ \ \ \ \ \ \ $*****$}
\maketitle
The $f_2(1270)$ is the lighter of the isospin neutral mesons containing only light quarks from the lightest tensor multiplet. The mass and width are taken from \cite{Yao:2006px}. The limit on the off-shellness of the particle is set to three times the width above the central mass and 250~MeV below central value to ensure the decays are possible. The four pion decay modes have been combined under the assumption that they consist of $\rho\rho$ and $\sigma\sigma$. The $\sigma\sigma$ term is need to account for the four neutral pion mode and gives contributions to the other modes. This procedure leads to a slight supression of the four pion modes and enhancement of the other modes. This is a different approach to EvtGen which includes the four pions modes.
The $f_2(1270)$ has mass $1275.4$~MeV and is unstable. The $f_2(1270)$ has spin $2$, charge $0$ and is colour neutral.
 The $f_2(1270)$ is a meson and is from the $1^3P_2$ multiplet.The $f_2(1270)$ has width $185.2$~MeV. The lower limit on the mass of the particle is $175$~MeV and the upper limit is $185.2$~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 225.
\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 $f_2(1270)$ (continues).}
\endfoot
\caption{The decay modes of the $f_2(1270)$.}
\endlastfoot
\label{tab:225decaymodes}
0.570829 & $*****$ & on & $ \pi^+, \pi^- $  & The decay of the $f_2(1270)$ to two charged pions. The branching ratio is higher than that in the \cite{Yao:2006px}, but within the error, to take account of our lower $\pi^+\pi^-\pi^0\pi^0$ rate and ensure the rates sum to one.   & Herwig::TensorMeson2PScalar::Tensor2PScalar \\ 
\hline
0.285414 & $*****$ & on & $ \pi^0, \pi^0 $  & The decay of the $f_2(1270)$ to two neutral pions. The branching ratio is higher than that in the \cite{Yao:2006px}, but within the error, to take account of our lower $\pi^+\pi^-\pi^0\pi^0$ rate and ensure the rates sum to one. N.B. this is half the $\pi^+\pi^-$ rate to take account of the identical particle symmetry factor.    & Herwig::TensorMeson2PScalar::Tensor2PScalar \\ 
\hline
0.046681 & $****$ & on & $ \rho^+, \rho^- $  & The decay of the $f_2(1270)$ to two charge $\rho$ mesons. This is the dominant contribution to the $\pi^+\pi^-\pi^0\pi^0$ mode, there is also a subdominant piece from the $\sigma\sigma$ mode. This gives a lower rate than in \cite{Yao:2006px} but is consistent within the errors.   & Herwig::TensorMesonVectorVector::TVV \\ 
\hline
0.023516 & $****$ & on & $ K^+, K^- $  & The decay of the $f_2(1270)$ to two kaons. This is half of the rate total $K\bar{K}$ rate due to the two possible final states. The branching ratio is higher than that in \cite{Yao:2006px} due to our lower four pion rates and the requirement that the branching ratios sum to one.   & Herwig::TensorMeson2PScalar::Tensor2PScalar \\ 
\hline
0.023516 & $****$ & on & $ K^0, \bar{K}^0 $  & The decay of the $f_2(1270)$ to two kaons. This is half of the rate total $K\bar{K}$ rate due to the two possible final states. The branching ratio is higher than that in \cite{Yao:2006px} due to our lower four pion rates and the requirement that the branching ratios sum to one.T   & Herwig::TensorMeson2PScalar::Tensor2PScalar \\ 
\hline
0.023340 & $****$ & on & $ \rho^0, \rho^0 $  & The decay of the $f_2(1270)$ to two neutral $\rho$ mesons. This is the dominant contribution to the $\pi^+\pi^-\pi^+\pi^-$ mode, there is also a subdominant piece from the $\sigma\sigma$ mode. This gives a higher rate than in \cite{Yao:2006px} but is consistent within the errors.   & Herwig::TensorMesonVectorVector::TVV \\ 
\hline
0.022649 & $***$ & on & $ \sigma, \sigma $  & The decay of the $f_2(1270)$ to $\sigma\sigma$. This contributes to all the four pion modes giving the only contribution to the four neutral pion mode and the subdominant contributions to the other modes.   & Herwig::TensorMeson2PScalar::Tensor2PScalar \\ 
\hline
0.004041 & $****$ & on & $ \eta, \eta $  & The decay of the $f_2(1270)$ to two eta mesons. The branching ratios is slightly larger than that taken from \cite{Yao:2006px} due to our lower four pion rates in order to ensure the branching ratios sum to one.   & Herwig::TensorMeson2PScalar::Tensor2PScalar \\ 
\hline
0.000014 & $****$ & on & $ \gamma, \gamma $  & The two photon decay mode of $f_2(1270)$ with branching ratio from \cite{Yao:2006px}.   & Herwig::TensorMesonVectorVector::TVV \\ 
\hline
\end{longtable}The $f_2(1270)$ decay modes are given in Table~\ref{tab:225decaymodes} and the total branching ratio is $1$.


The mass generator is \verb|f_2mass| for the $f_2(1270)$.
The width generator is \verb|f_2width| for the $f_2(1270)$.

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 The particle was checked by Peter Richardson at 12:11:3 on the 15th of November 2007. The most recently changed decay mode was modified at 14:53:20 on the 13th of October 2006. The particle data was last modified at 12:10:57 on the 15th of November 2007.

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