Rivet analyses

title: ARGUS_1989_I267206

$\bar{B}^0\to D^{*+}\ell^-\bar\nu_\ell$

Experiment: ARGUS (DORIS)

Inspire ID: 267206

Status: VALIDATED NOHEPDATA

Authors: - Peter Richardson

References: - Phys.Lett.B 219 (1989) 121-126

Beams: * *

Beam energies: ANY

Run details: - Any process producing B mesons, originally Upsilon(4S) decays

$q^2$ spectrum, lepton momentum spectrum and $D^$ helicty angle in $\bar{B}^0\to D^{+}\ell^-\bar\nu_\ell$. Corrected data read from figure 7.

Source code:ARGUS_1989_I267206.cc

```c++ // -- C++ --

include "Rivet/Analysis.hh"

include "Rivet/Projections/DecayedParticles.hh"

include "Rivet/Projections/UnstableParticles.hh"

namespace Rivet {

/// @brief Bbar0 -> D* l nu class ARGUS_1989_I267206 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(ARGUS_1989_I267206);


/// @name Analysis methods
/// @{

/// Book histograms and initialise projections before the run
void init() {
  // Initialise and register projections
  UnstableParticles ufs = UnstableParticles(Cuts::abspid == 511);
  declare(ufs, "UFS");
  DecayedParticles BB(ufs);
  BB.addStable(411);
  BB.addStable(-411);
  BB.addStable(421);
  BB.addStable(-421);
  BB.addStable(413);
  BB.addStable(-413);
  BB.addStable(423);
  BB.addStable(-423);
  BB.addStable(PID::PI0);
  declare(BB, "BB");
  // histos
  for (unsigned int ix = 0; ix < 3; ++ix) {
    book(_h[ix], 1 + ix, 1, 1);
  }
}


/// Perform the per-event analysis
void analyze(const Event& event) {
  // loop over B mesons
  DecayedParticles BB = apply<DecayedParticles>(event, "BB");
  // loop over particles
  for (unsigned int ix = 0; ix < BB.decaying().size(); ++ix) {
    for (unsigned int il = 0; il < 2; ++il) {
      if (BB.modeMatches(ix, 3, mode[il])) {
        int sign = il % 2 == 0 ? -1 : 1;
        const Particle& DD = BB.decayProducts()[ix].at(sign * 413)[0];
        const Particle& em = BB.decayProducts()[ix].at(sign * 11)[0];
        FourMomentum qq = BB.decaying()[ix].mom() - DD.mom();
        _h[1]->fill(em.mom().p3().mod());
        _h[2]->fill(qq.mass2());
        if (DD.children().size() != 2) continue;
        // boost to B rest frame
        LorentzTransform boost1 = LorentzTransform::mkFrameTransformFromBeta(
            BB.decaying()[ix].mom().betaVec());
        FourMomentum pDD = boost1.transform(DD.mom());
        Particle D0;
        if (DD.children()[0].pid() == sign * 211 && DD.children()[1].pid() == sign * 421) {
          D0 = DD.children()[1];
        }
        else if (DD.children()[1].pid() == sign * 211 && DD.children()[0].pid() == sign * 421) {
          D0 = DD.children()[0];
        }
        else {
          continue;
        }
        FourMomentum pD0 = boost1.transform(D0.mom());
        LorentzTransform boost3 = LorentzTransform::mkFrameTransformFromBeta(pDD.betaVec());
        pD0 = boost3.transform(pD0);
        double cTheta = pD0.p3().unit().dot(pDD.p3().unit());
        _h[0]->fill(cTheta);
      }
    }
  }
}


/// Normalise histograms etc., after the run
void finalize() {
  normalize(_h, 1.0, false);
}

/// @}


/// @name Histograms
/// @{
Histo1DPtr _h[3];
const map<PdgId, unsigned int> mode[2] = {{{-413, 1}, {-11, 1}, {12, 1}}, {{413, 1}, {11, 1}, {-12, 1}}};
/// @}

};

RIVET_DECLARE_PLUGIN(ARGUS_1989_I267206);

} ```