include/EvtGenModels/EvtSVVNONCPEIGEN.hh

0001
0002 /***********************************************************************
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0020
0021 #ifndef EVTSVVNONCPEIGEN_HH
0022 #define EVTSVVNONCPEIGEN_HH
0023
0024 #include "EvtGenBase/EvtDecayAmp.hh"
0025
0026 class EvtParticle;
0027
0028 // Description: Routine to decay scalar -> vector vector
0029 //              and has CP violation.
0030 //
0031 //              This model does all the ckm-suppressed decays and mixing for you. It randomly 'overwrites'
0032 //              any reco or tagging state as set in the Y(4S) decay model (VSS_(B)MIX) with its own generated states.
0033 //
0034 //              As such, the corresponding dec file requires only one decay-mode description, for example:
0035 //              Decay MyB0
0036 //              1.000    rho+ MyD*-       SVV_NONCPEIGEN dm beta gamma 0.322 0.31 0.941 0 0.107 1.42 0.02 0 0.02 0 0.02 0 ;
0037 //              EndDecay
0038 //              and furthermore Y(4S) only needs to decay to B0's (or B0bar's).
0039 //              The decay above should be a CKM-favored mode (eg. B0->D*-rho+ or B0bar->D*+rho-).
0040 //              All ckm-suppressed decays and the mixing are derived from this line in the ::Decay function.
0041 //
0042 //              There are 15 or 27 arguments. The first three are dm, phase1
0043 //              and phase2. dm is the B0-B0bar mass difference. Phases 1
0044 //              and 2 are the CKM weak phases relevant for the particular mode,
0045 //              eg for B-->DstRho phase1 is beta and phase2 is gamma.
0046 //
0047 //              The next arguments are the 2 amplitudes (= 12 input parameters)
0048 //              in the order: A_f, Abar_f. In the example above, the 'A_f' amplitude now
0049 //              stands for the ckm-favored decay 'B0->D*-rho+', and 'Abar_f' stands for 'B0bar->D*-rho+'
0050 //
0051 //              Each amplitude has its 3 helicity states in the order +, 0, -, which are each
0052 //              specified by a magnitude and a strong phase.
0053 //
0054 //              The last 2 arguments A_fbar and Abar_fbar (=12 input parameters) are not necessary,
0055 //              but can included if one wants to set them differently from A_f, Abar_f.
0056 //
0057 //              Mind you that Hbar_+- = H_-+ (ignoring the weak phase, which flips sign).
0058 //              It is custumary to select one set of helicity states (eg H_+-) and to adopt these for
0059 //              the CP-conjugate decays as well (ie. depict Hbar_-+ with H_+-), which is the interpretation
0060 //              we use for the input-parameters above.
0061 //              However, the angular decay in EvtGen is just a formula in which helicity amplitudes are 'plugged' in,
0062 //              making no difference between B0 or B0bar decays. In the model below we (thus) account for the +-
0063 //              flipping between B0 and B0bar.
0064
0065 class EvtSVVNONCPEIGEN : public EvtDecayAmp {
0066   public:
0067     std::string getName() override;
0068     EvtDecayBase* clone() override;
0069
0070     void initProbMax() override;
0071     void init() override;
0072
0073     void decay( EvtParticle* p ) override;
0074
0075     std::string getParamName( int i ) override;
0076     std::string getParamDefault( int i ) override;
0077
0078   private:
0079     EvtComplex _A_f[12];
0080 };
0081
0082 #endif