Formalism-I

Support material for https://inspirehep.net/record/1642229

The repository contains jupyter notebooks with the implementation of the formalism and integration over the final state. Julia kernel is used for the notebooks. It is supposed to be extended with the C++ library to use the formalism in the decay.

The folder cpp-implementation contains the c++ version of the formalism and the example of usage.

• The file FormalismI.cc provides the functionality to compute the amplitude.
• The file Generator.cc gives the set of functions to generate four-vectors
• The file Example.cc shows the usage example: the amplitude and density is computed for a single event.
• The file DalitzPlot.cc generate events according to the phase space and weight them with the density calculated using the formalism. The program outputs s,t, and the weight. The program takes the number of events as the first argument.

How to run notebooks

use JuliaBox, clone this repository and play around.

How to compile and run the program

The Clebsch-Gordon coefficients are called from GSL-library. Therefore, the program must be linked against lgsl. It is already stored at your machine because it is used by ROOT.

1. First, locate the header and the library for the gsl dependence.

locate gsl_sf_coupling.h
locate libgsl.a

You need to specify the path to folder gsl/ where the headers are stored with the frag -I. The path to the library has to be given with the flag -L.

2. Compile and link

g++ -std=c++11 -L${PATH_TO_GSL_LIBRARY} -I${PATH_TO_GSL_FOLDER} -o Example Example.cc -lgsl

Alternatively, export the variables PATH_TO_GSL_LIBRARY and PATH_TO_GSL_FOLDER then use the make-command

3. Run

./Example