\section{XML Interface}
\index{xml}
\label{sec:xml}
This section describes the XML interface for EvtGen. The XML interface can be used to configure EvtGen at runtime and is designed to replace the old decay file format.

\subsection{alias}
\index{aliasTag}
\index{xml!aliasTag}
Defines an alias for a particle.
\subsubsection*{Attributes}
\begin{itemize}
\item{\tt name}\\
      The name of the alias.
\item{\tt particle}\\
      The name of the particle.
\end{itemize}
\subsubsection*{Tags}
This tag has no tags.
\subsubsection*{Example}
{\footnotesize
\begin{verbatim}
<alias name="B+sig" particle"B+"/>
\end{verbatim}
}

\subsection{Author}
\index{authorTag}
\index{xml!authorTag}
Ignored by EvtGen.
\subsubsection*{Attributes}
This tag has no attributes.
\subsubsection*{Tags}
This tag has no tags.

\subsection{channel}
\index{channelTag}
\index{xml!channelTag}
Contains a single decay channel.
\subsubsection*{Attributes}
\begin{itemize}
\item{\tt br}\\
      The branching fraction of this channel.
\item{\tt daughters}\\
      A space-separated list of the daughters produced in this channel.
\item{\tt model}\\
      The name of the decay model used to model this decay channel.
\item{\tt params}\\
      A space-separated list of parameters to configure the decay model.
\item{\tt photos}\\
      Turn on PHOTOS for this decay.\\
      \emph{Default: off}
\item{\tt verbose}\\
      Turn on verbose for this decay.\\
      \emph{Default: off}
\item{\tt summary}\\
      Turn on summary for this decay.\\
      \emph{Default: off}
\end{itemize}
\subsubsection*{Tags}
This tag has no tags.
\subsubsection*{Example}
{\footnotesize
\begin{verbatim}
<channel br="0.515122645" daughters="B+ B-" model="VSS"/>
\end{verbatim}
}

\subsection{chargeConj}
\index{chargeConjTag}
\index{xml!chargeConjTag}
Defines two particle aliases as eachothers charge conjugates.
\subsubsection*{Attributes}
\begin{itemize}
\item{\tt particle}\\
      The name of the first particle.
\item{\tt conjugate}\\
      The name of the second particle.\\
      \emph{Note: The order of these parameters is not important.}
\end{itemize}
\subsubsection*{Tags}
This tag has no tags.
\subsubsection*{Example}
{\footnotesize
\begin{verbatim}
<chargeConj particle="B+sig" conjugate="B-sig"/>
\end{verbatim}
}

\subsection{conjDecay}
\index{conjDecayTag}
\index{xml!conjDecayTag}
Define a particle's decay based on that of its charge conjugate.
\subsubsection*{Attributes}
\begin{itemize}
\item{\tt particle}\\
      The name of the particle to be modified.
\end{itemize}
\subsubsection*{Tags}
This tag has no tags.
\subsubsection*{Example}
{\footnotesize
\begin{verbatim}
<conjDecay particle="tau+"/>
\end{verbatim}
}

\subsection{copyDalitz}
\index{copyDalitzTag}
\index{xml!copyDalitzTag}
Defines a new Dalitz decay with the same resonance structure as an existing one.\\
\emph{Used by EvtGenericDalitz}
\subsubsection*{Attributes}
\begin{itemize}
\item{\tt particle}\\
      The name of the decaying particle.
\item{\tt daughters}\\
      A space-separated list of the daughters produced in this channel.\\
      \emph{Note: The order of daughters is important.}
\item{\tt copy}\\
      The decaying particle in the channel to be copied.
\item{\tt copyDaughters}\\
      A space-separated list of the daughters of the channel to be copied.
\end{itemize}
\subsubsection*{Tags}
This tag has no tags.
\subsubsection*{Example}
{\footnotesize
\begin{verbatim}
<copyDalitz particle="D-" daughters="K+ pi- pi-"
            copy="D+" copyDaughters="K- pi+ pi+"/>
\end{verbatim}
}

\subsection{copyDecay}
\index{copyDecayTag}
\index{xml!copyDecayTag}
Copy the definition of one particle's decays to another particle.
\subsubsection*{Attributes}
\begin{itemize}
\item{\tt particle}\\
      The name of the particle to be modified.
\item{\tt copy}\\
      The name of the particle to be copied.
\end{itemize}
\subsubsection*{Tags}
This tag has no tags.
\subsubsection*{Example}
{\footnotesize
\begin{verbatim}
<copyDecay particle="B+sig" copy="B+"/>
\end{verbatim}
}

\subsection{dalitzDecay}
\index{dalitzDecayTag}
\index{xml!dalitzDecayTag}
Configures the Dalitz decay model for a given decay.\\
\emph{Used by EvtGenericDalitz}
\subsubsection*{Attributes}
\begin{itemize}
\item{\tt particle}\\
      The name of the decaying particle.
\item{\tt daughters}\\
      A space-separated list of the daughters produced in this channel.
\item{\tt probMax}\\
      Must be calibrated for each decay seperately.
\end{itemize}
\subsubsection*{Tags}
resonance.
\subsubsection*{Example}
{\footnotesize
\begin{verbatim}
<dalitzDecay particle="D+" daughters="anti-K0 pi+ pi0" probMax="150.0">
  <resonance real="-0.268361" imag="-0.913601" shape="NonRes"/>
  <resonance mag="0.388844" phase="0.00" width="0.1512"
             mass="0.7699" spin="1" resDaughters="pi+ pi0"
             shape="RBW" BlattWeisskopfFactorResonance="25.38"/>
  <resonance mag="0.1940367505" phase="41.201" width="0.0498"
             mass="0.89159" spin="1" resDaughters="pi0 anti-K0"
             shape="RBW" BlattWeisskopfFactorResonance="10.15"/>
</dalitzDecay>
\end{verbatim}
}

\subsection{data}
\index{dataTag}
\index{xml!dataTag}
This is the top-level tag that must contain all other tags.
\subsubsection*{Attributes}
This tag has no attributes.
\subsubsection*{Tags}
alias, Author, chargeConj, copyDalitz, copyDecay, dalitzDecay, decay, define, Details, lineShapePW, modelAlias, particle, photos, pythia6Param, pythiaParam, removeDecay, Title, Version.

\subsection{decay}
\index{decayTag}
\index{xml!decayTag}
Contains the decay information of a single particle.
\subsubsection*{Attributes}
\begin{itemize}
\item{\tt name}\\
      The name of the decaying particle.
\end{itemize}
\subsubsection*{Tags}
channel.
\subsubsection*{Example}
{\footnotesize
\begin{verbatim}
<decay name="Upsilon(4S)">
  <channel br="0.515122645" daughters="B+ B-" model="VSS"/>
  <channel br="0.483122645" daughters="B0 anti-B0" model="VSS_BMIX" params="dm"/>
  <channel br="0.000015583" daughters="e+ e-" model="VLL" photos="true"/>
  <channel br="0.000015766" daughters="mu+ mu-" model="VLL" photos="true"/>
  <channel br="0.000015766" daughters="tau+ tau-" model="VLL" photos="true"/>
  <channel br="0.000084099" daughters="Upsilon(2S) pi+ pi-" model="VVPIPI"/>
  <channel br="0.000044342" daughters="Upsilon(2S) pi0 pi0" model="VVPIPI"/>
  <channel br="0.000080123" daughters="Upsilon pi+ pi-" model="VVPIPI"/>
  <channel br="0.000044342" daughters="Upsilon pi0 pi0" model="VVPIPI"/>
  <channel br="0.000194392" daughters="Upsilon eta" model="PARTWAVE"
           params="0.0 0.0 1.0 0.0 0.0 0.0"/>
  <channel br="0.000092625" daughters="gamma chi_b0(3P)" model="HELAMP"
           params="1. 0. 1. 0."/>
  <channel br="0.000138938" daughters="gamma chi_b1(3P)" model="HELAMP"
           params="1. 0. 1. 0. -1. 0. -1. 0."/>
  <channel br="0.000129084" daughters="gamma chi_b2(3P)" model="HELAMP"
           params="2.4494897 0. 1.7320508 0. 1. 0. 1. 0. 1.7320508 0. 2.4494897 0."/>
  <channel br="0.000002956" daughters="gamma chi_b0(2P)" model="HELAMP"
           params="1. 0. 1. 0."/>
  <channel br="0.000007883" daughters="gamma chi_b1(2P)" model="HELAMP"
           params="1. 0. 1. 0. -1. 0. -1. 0."/>
  <channel br="0.000011825" daughters="gamma chi_b2(2P)" model="HELAMP"
           params="2.4494897 0. 1.7320508 0. 1. 0. 1. 0. 1.7320508 0. 2.4494897 0."/>
  <channel br="0.000837571" daughters="g g g" model="PYTHIA" params="4"/>
  <channel br="0.000039415" daughters="gamma g g" model="PYTHIA" params="4"/>
</decay>
\end{verbatim}
}

\subsection{define}
\index{defineTag}
\index{xml!defineTag}
Defines a constant.
\subsubsection*{Attributes}
\begin{itemize}
\item{\tt name}\\
      The name of the constant.
\item{\tt value}\\
      The numeric value of the constant.
\end{itemize}
\subsubsection*{Tags}
This tag has no tags.
\subsubsection*{Example}
{\footnotesize
\begin{verbatim}
<define name="gamma" value="1.387"/>
\end{verbatim}
}

\subsection{Details}
\index{detailsTag}
\index{xml!detailsTag}
Ignored by EvtGen.
\subsubsection*{Attributes}
This tag has no attributes.
\subsubsection*{Tags}
This tag has no tags.

\subsection{lineShapePW}
\index{lineShapePWTag}
\index{xml!lineShapePWTag}
Define the lowest allowed partial wave for a two body decay.
\subsubsection*{Attributes}
\begin{itemize}
\item{\tt parent}\\
      The name of the decaying particle.
\item{\tt daug1}\\
      The name of the first daughter particle.
\item{\tt daug2}\\
      The name of the second daughter particle.\\
      \emph{The order of {\tt daug1} and {\tt daug2} is not important.}
\item{\tt pw}\\
      The partial wave spin.
\end{itemize}
\subsubsection*{Tags}
This tag has no tags.
\subsubsection*{Example}
{\footnotesize
\begin{verbatim}
<lineShapePW parent="MyD_1+" daug1="MyD*+" daug2="pi0" pw="2"/>
\end{verbatim}
}

\subsection{modelAlias}
\index{modelAliasTag}
\index{xml!modelAliasTag}
Defines an alias for a model.\\
\emph{Useful for models which are used frequently with the same parameters.}
\subsubsection*{Attributes}
\begin{itemize}
\item{\tt name}\\
      The name of the alias.
\item{\tt model}\\
      The name of the model that this alias is for.
\item{\tt params}\\
      The parameters to be passed to the model when using this alias.
\end{itemize}
\subsubsection*{Tags}
This tag has no tags.
\subsubsection*{Example}
{\footnotesize
\begin{verbatim}
<modelAlias name="MYPARTWAVE" model="PARTWAVE" params="0.0 0.0 1.0 0.0 0.0 0.0"/>
\end{verbatim}
}

\subsection{particle}
\index{particleTag}
\index{xml!particleTag}
Contains modifications to a defined particle.
\subsubsection*{Attributes}
\begin{itemize}
\item{\tt name}\\
      The name of the particle to be modified.
\item{\tt mass}\\
      The mass of the particle.
\item{\tt width}\\
      The width of the particle.
\item{\tt massMax, massMin}\\
      The maximum and minimum allowed masses for the particle.
\item{\tt includeBirthFactor, includeDecayFactor}\\
      Whether birth and decay factors should be included for the particle.
\item{\tt lineShape}\\
      Takes the values RELBW, NONRELBW, FLAT, MANYDELTAFUNC.
\item{\tt blattWeisskopfFactor}\\
      The BlattWeisskopf factor associated with the particle.
\end{itemize}
\subsubsection*{Tags}
This tag has no tags.
\subsubsection*{Example}
{\footnotesize
\begin{verbatim}
<particle name="Myf_0" mass="0.980" width="0.092" massMin="0"/>
\end{verbatim}
}

\subsection{photos}
\index{photosTag}
\index{xml!photosTag}
Configure PHOTOS.
\subsubsection*{Attributes}
\begin{itemize}
\item{\tt usage}\\
      Configure usage of PHOTOS. Takes the values always or never.\\
      \emph{Overrides the {\tt photos} parameter of the channel tag when set.}
\end{itemize}
\subsubsection*{Tags}
This tag has no tags.
\subsubsection*{Example}
{\footnotesize
\begin{verbatim}
<photos usage="always"/>
\end{verbatim}
}

\subsection{pythiaParam}
\index{pythiaParamTag}
\index{xml!pythiaParamTag}
Configure PYTHIA.
\subsubsection*{Attributes}
\begin{itemize}
\item{\tt generator}\\
      The generator this should be applied to. Takes the values generic, alias or both.
\item{\tt module}\\
      The name of the PYTHIA8 module.
\item{\tt param}\\
      The name of the PYTHIA8 parameter.
\item{\tt value}\\
      The value to give the parameter.
\end{itemize}
\subsubsection*{Tags}
This tag has no tags.
\subsubsection*{Example}
{\footnotesize
\begin{verbatim}
<pythiaParam generator="BOTH" module="ParticleDecays" param="multIncrease" value="10"/>
\end{verbatim}
}

\subsection{pythia6Param}
\index{pythia6ParamTag}
\index{xml!pythia6ParamTag}
Configure PYTHIA.\\
\emph{Apply PYTHIA6 configuration to PYTHIA8}
\subsubsection*{Attributes}
\begin{itemize}
\item{\tt generator}\\
      The generator this should be applied to. Takes the values generic, alias or both.
\item{\tt module}\\
      The name of the PYTHIA6 module.
\item{\tt param}\\
      The number of the PYTHIA6 parameter.
\item{\tt value}\\
      The value to give the parameter.
\end{itemize}
\subsubsection*{Tags}
This tag has no tags.
\subsubsection*{Example}
{\footnotesize
\begin{verbatim}
<pythia6Param generator="GENERIC" module="MSTJ" param="26" value="0"/>
\end{verbatim}
}

\subsection{removeDecay}
\index{removeDecayTag}
\index{xml!removeDecayTag}
Remove a decay channel from the decay of a particle.\\
\emph{Used in conjunction with copyDecay}
\subsubsection*{Attributes}
\begin{itemize}
\item{\tt particle}\\
      The name of the decaying particle.
\end{itemize}
\subsubsection*{Tags}
channel.
\subsubsection*{Example}
{\footnotesize
\begin{verbatim}
<removeDecay particle="myPhi">
  <channel daughters="K+ K-"/>
</removeDecay>
\end{verbatim}
}

\subsection{resonance}
\index{resonanceTag}
\index{xml!resonanceTag}
Contains a single resonance that contributes to a Dalitz decay.\\
\emph{Used by EvtGenericDalitz}
\subsubsection*{Attributes}
\begin{itemize}
\item{\tt mag, phase}\\
      The magnitude and phase of the resonance.\\
      \emph{Defaults: 1, 0}
\item{\tt real, imag}\\
      The real and imaginary components of the resonances amplitude.\\
      \emph{Overridden by \tt mag, phase}
\item{\tt ampFactorReal, ampFactorImag}\\
      Further multiplicative factor for the amplitude.\\
      \emph{Defaults: 1, 0}
\item{\tt particle}\\
      The name of the resonant particle to obtain mass, spin and width from.\\
      \emph{Overridden by \tt mass, spin, width}
\item{\tt mass, spin, width}\\
      The mass, spin and width of the resonant particle.
\item{\tt shape}\\
      The shape of the resonance.\\
      \emph{Can take the values: NBW, RBW, RBW\_CLEO\_ZEMACH, NonRes, Flatte.}
\item{\tt BlattWeisskopfFactorParent, BlattWeisskopfFactorResonance}\\
      The BlattWeisskopf factors associated with the parent and the resonance.\\
      \emph{Defaults: 0.0, 1.5}
\item{\tt resDaughters}\\
      A space-separated list of the daughters produced by the resonance.
\item{\tt daughterPair}\\
      The pair of daughters associated with the resonance 1=AB, 2=BC, 3=CA.\\
      \emph{Overridden by \tt resDaughters}
\item{\tt normalise}\\
      If multiple daughter pairs match the {\tt resDaughters} string then their amplitudes will be normalised unless this is turned off.\\
      \emph{Default: on}
\end{itemize}
\subsubsection*{Tags}
This tag has no tags.
\subsubsection*{Example}
{\footnotesize
\begin{verbatim}
<resonance mag="0.96" phase="150.1" width="0.109"
           mass="1.4324" spin="2" resDaughters="pi+ K-"
           shape="RBW_CLEO_ZEMACH" BlattWeisskopfFactorParent="5.0"/>
\end{verbatim}
}

\subsection{Title}
\index{titleTag}
\index{xml!titleTag}
Ignored by EvtGen.
\subsubsection*{Attributes}
This tag has no attributes.
\subsubsection*{Tags}
This tag has no tags.

\subsection{Version}
\index{versionTag}
\index{xml!versionTag}
Ignored by EvtGen.
\subsubsection*{Attributes}
This tag has no attributes.
\subsubsection*{Tags}
This tag has no tags.