D02K3pi binning scheme

A package for dividing the phase space of \(D^0 \to K \pi\pi\pi\) decays into bins. Code is provided to evaluate the CF/DCS amplitude models from the LHCb collaboration presented in this paper. Code is then provided to calculate which phase-space bin a given decay falls into based on these models, using a binning based the phase differences predicted by the models.

The header file provides class k3pi_binning::binning that takes a set of four vectors and calculates which phase-space bin the decay is located in. An example ROOT macro using this class can be found in example_k3pi_binning.cpp.

Each of the amplitudes is evaluated by a standalone shared library, the code for which can be found in dcs.cpp and cf.cpp This code for the amplitudes is linked at runtime to the code that evaluates the bins by the k3pi_binning class, with the paths to the shared libraries taken as arguments by the constructor. The source code for these was generated using the AmpGen package. The options files that generate this source code can be found in D02piKpipi.opt and Dbar02piKpipi.opt for DCS and CF amplitudes, respectively.

The amplitude source code can be built into shared libraries to be used with the binning with the command:

g++ -Ofast -shared -rdynamic --std=c++14 -fPIC -march=native models/dcs.cpp -o models/dcs.so
g++ -Ofast -shared -rdynamic --std=c++14 -fPIC -march=native models/cf.cpp  -o models/cf.so

and then used to evaluate each amplitude, and the respective phase-space bin.

Includes:

• k3pi_binning.h: Header file that provides class to calculate bin numbers k3pi_binning::binning.
• example_k3pi_binning.cpp: ROOT macro that shows example usage of k3pi_binning::binning.
• dcs.cpp,cf.cpp: Source code to evaluate dcs/cf amplitudes.
• Dbar02piKpipi.opt / D02Kpipipi.opt: Options files that generate source code for amplitude models of  \(\bar{D}^0 \to K^+ \pi^- \pi^- \pi^+\) and \(D^0 \to K^- \pi^+ \pi^+ \pi^- \) decays.
• D02piKpipi.opt: Options file that generates source for the amplitude model of \(D^0 \to K^+ \pi^- \pi^- \pi^+\)  decays.