Rivet analyses

title: CDF_2009_I817466

CDF Run 2 min bias cross-section analysis

Experiment: CDF (Tevatron Run 2)

Inspire ID: 817466

Status: VALIDATED

Authors: - Hendrik Hoeth - Niccolo' Moggi

References: - Phys.Rev.D79:112005,2009 - DOI: 10.1103/PhysRevD.79.112005 - arXiv: 0904.1098

Beams: p- p+

Beam energies: (980.0, 980.0)GeV

Run details: - $p\bar{p}$ QCD interactions at 1960~GeV. Particles with $c \tau > 10$ mm should be set stable.

Niccolo Moggi's min bias analysis. Minimum bias events are used to measure the average track pT vs. charged multiplicity, a track pT distribution and an inclusive $\sum E_T$ distribution.

Source code:CDF_2009_I817466.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Projections/ChargedFinalState.hh"

include "Rivet/Projections/FinalState.hh"

include "Rivet/Projections/TriggerCDFRun2.hh"

namespace Rivet {

/// @brief CDF Run II min-bias cross-section /// /// @author Hendrik Hoeth /// /// Measurement of \f$ \langle p_T \rangle \f$ vs. \f$ n_\text{ch} \f$, /// the track \f$ p_T \f$ distribution, and the \f$ \sum E_T \f$ distribution. /// Particles are selected within |eta|<1 and with pT>0.4 GeV. /// There is no pT cut for the \f$ \sum E_T \f$ measurement. /// /// @par Run conditions /// /// @arg \f$ \sqrt{s} = \f$ 1960 GeV /// @arg Run with generic QCD events. /// @arg Set particles with c*tau > 10 mm stable class CDF_2009_I817466 : public Analysis { public:

RIVET_DEFAULT_ANALYSIS_CTOR(CDF_2009_I817466);


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

/// Book histograms and projections
void init() {
  declare(TriggerCDFRun2(), "Trigger");
  declare(FinalState((Cuts::etaIn(-1.0, 1.0))), "EtFS");
  declare(ChargedFinalState((Cuts::etaIn(-1.0, 1.0) && Cuts::pT >= 0.4 * GeV)), "CFS");

  book(_hist_pt, 1, 1, 1);
  book(_hist_pt_vs_multiplicity, 2, 1, 1);
  book(_hist_sumEt, 3, 1, 1);

  book(_sumWeightSelected, "_sumWeightSelected");
}


/// Do the analysis
void analyze(const Event& evt) {
  // MinBias Trigger
  const bool trigger = apply<TriggerCDFRun2>(evt, "Trigger").minBiasDecision();
  if (!trigger) vetoEvent;

  /// @todo The pT and sum(ET) distributions look slightly different from
  ///       Niccolo's Monte Carlo plots. Still waiting for his answer.

  const ChargedFinalState& trackfs = apply<ChargedFinalState>(evt, "CFS");
  const size_t numParticles = trackfs.size();
  for (const Particle& p : trackfs.particles()) {
    const double pT = p.pT() / GeV;
    _hist_pt_vs_multiplicity->fill(numParticles, pT);

    // The weight for entries in the pT distribution should be weight/(pT*dPhi*dy).
    //
    // - dPhi = 2*PI
    //
    // - dy depends on the pT: They calculate y assuming the particle has the
    //   pion mass and assuming that eta=1:
    //   dy = 2 * 1/2 * ln [(sqrt(m^2 + (a+1)*pT^2) + a*pT) / (sqrt(m^2 + (a+1)*pT^2) - a*pT)]
    //   with a = sinh(1).
    //
    // sinh(1) = 1.1752012
    // m(charged pion)^2 = (139.57 MeV)^2 = 0.019479785 GeV^2
    const double sinh1 = 1.1752012;
    const double apT = sinh1 * pT;
    const double mPi = 139.57 * MeV;
    const double root = sqrt(mPi * mPi + (1 + sinh1) * pT * pT);
    const double dy = std::log((root + apT) / (root - apT));
    const double dphi = TWOPI;
    _hist_pt->fill(pT, 1.0 / (pT * dphi * dy));
  }

  // Calc sum(Et) from calo particles
  const FinalState& etfs = apply<FinalState>(evt, "EtFS");
  double sumEt = 0.0;
  for (const Particle& p : etfs.particles()) {
    sumEt += p.Et();
  }
  _hist_sumEt->fill(sumEt);
  _sumWeightSelected->fill();
}


/// Normalize histos
void finalize() {
  scale(_hist_sumEt, crossSection() / millibarn / (4 * M_PI * dbl(*_sumWeightSelected)));
  scale(_hist_pt, crossSection() / millibarn / dbl(*_sumWeightSelected));
  MSG_DEBUG("sumOfWeights()     = " << sumOfWeights());
  MSG_DEBUG("_sumWeightSelected = " << dbl(*_sumWeightSelected));
}

/// @}

private:

CounterPtr _sumWeightSelected;
Profile1DPtr _hist_pt_vs_multiplicity;
Histo1DPtr _hist_pt;
Histo1DPtr _hist_sumEt;

};

RIVET_DECLARE_ALIASED_PLUGIN(CDF_2009_I817466, CDF_2009_S8233977);

} ```

Aliases: - CDF_2009_S8233977