// Example from the Oxbridge Stransverse Mass Library -- oxbridgekinetics. // See http://www.hep.phy.cam.ac.uk/~lester/mt2/index.html // Authors: Christopher Lester and Alan Barr #include "ExampleEvent.h" #include "Mt2/ChengHanBisect_Mt2_332_Calculator.h" #include "Mt2/Basic_Mt2_332_Calculator.h" #include "Mt2/Mt2Calculators.h" #include int main(int argc, char * argv[]) { // For the example. we now need some momenta and masses from which // to calculate MT2. // // In "reality" we would get these momenta from an ntuple or // from a physics event. // // As this is just an example program, we will instead get // some "example" momenta from the class "ExampleEvent" // defined in "ExampleEvent.h"as follows: ExampleEvent exampleEvent; for (int i=0; i<3; ++i) { if (i==1) { exampleEvent.resetZhenA_332(); } else if (i==2) { exampleEvent.resetCowden(); } Mt2::LorentzTransverseVector ltv_Vis_A = exampleEvent. ltv_Vis_A(); Mt2::LorentzTransverseVector ltv_Vis_B = exampleEvent. ltv_Vis_B(); Mt2::TwoVector pT_Miss = exampleEvent. pT_Miss(); double invis_mass = exampleEvent.invis_mass(); std::cout << "Going to calculate MT2 with\n" << " ltv_Vis_A = " << ltv_Vis_A << "\n" << " ltv_Vis_B = " << ltv_Vis_B << "\n" << " pT_Miss = " << pT_Miss << "\n" << " invis_mass = " << invis_mass << std::endl; // Now that we have some visiable momenta and some missing transverse // momentum we can calculate MT2. // First we create the object that is going to do the calculation // of MT2 for us. // // For this example we will use a modification of the "332" aglorithm // that was originally defined in SUSYPhys. Our modification (called // ChengHanBisect_Mt2_332_Calculator) is basically the same as // SUSYPhys_Mt2_222_Calculator except that we remove the assumption // that visible particles are massless. Mt2::ChengHanBisect_Mt2_332_Calculator mt2Calculator1; Mt2::Basic_Mt2_332_Calculator mt2Calculator2; Mt2::Basic_Mt2_44411_Calculator mt2Calculator3; // Could tell the MT2 calculating object to be verbose, and print out // debug messages while it is thinking ... but we won't: // mt2Calculator.setDebug(true); // Now we can actually calculate MT2: const double mt2_1 = mt2Calculator1.mt2_332( ltv_Vis_A, ltv_Vis_B, pT_Miss, invis_mass); const double mt2_2 = mt2Calculator2.mt2_332( ltv_Vis_A, ltv_Vis_B, pT_Miss, invis_mass); const double mt2_3 = mt2Calculator3.mt2_44411( exampleEvent.p_Vis_A(), exampleEvent.p_Vis_B(), exampleEvent.p_Vis_Other(), exampleEvent.rootS(), invis_mass); // Now we print out the result: std::cout << "ANSWER: mt2 =" << "\t" << mt2_1 << " for " << mt2Calculator1.algorithmName() << "\t" << "\t" << mt2_2 << " for " << mt2Calculator2.algorithmName() << "\t" << "\t" << mt2_3 << " for " << mt2Calculator3.algorithmName() << "\t" << std::endl; } return 0; }