Rivet analyses

title: CDF_2012_NOTE10874

CDF energy scan underlying event analysis

Experiment: CDF (Tevatron energy scan)

Status: VALIDATED

Authors: - Rick Field

References: - CDF Note 10874

Beams: p- p+

Beam energies: (150.0, 150.0); (450.0, 450.0); (980.0, 980.0)GeV

Run details: - $p\bar{p}$ QCD interactions at 300, 900, and 1960~GeV. Particles with $c \tau > {}$10 mm should be set stable.

In this analysis the behavior of the underlying event in hard scattering proton-antiproton collisions at 300 GeV, 900 GeV, and 1.96 TeV is studied. The 300 GeV and 900 GeV data are a result of the Tevatron Energy Scan which was performed just before the Tevatron was shut down.

Source code:CDF_2012_NOTE10874.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Projections/ChargedFinalState.hh"

namespace Rivet {

class CDF_2012_NOTE10874 : public Analysis { public:

RIVET_DEFAULT_ANALYSIS_CTOR(CDF_2012_NOTE10874);

public:

void init() {
  const ChargedFinalState cfs(Cuts::abseta < 1.0 && Cuts::pT >= 0.5 * GeV);
  declare(cfs, "CFS");

  size_t ih = 1;
  for (double eVal : allowedEnergies()) {
    const string en = toString(round(eVal));
    if (isCompatibleWithSqrtS(eVal)) _sqs = en;
    book(_p[en + "nch_transverse"], 1, 1, ih);
    book(_p[en + "ptSumDen"], 2, 1, ih);
    book(_p[en + "avePt"], 3, 1, ih);
    ++ih;
  }
  raiseBeamErrorIf(_sqs.empty());
}

// Little helper function to identify Delta(phi) regions
inline int region_index(double dphi) {
  assert(inRange(dphi, 0.0, PI, CLOSED, CLOSED));
  if (dphi < PI / 3.0) return 0;
  if (dphi < 2 * PI / 3.0) return 1;
  return 2;
}


void analyze(const Event& event) {
  const ChargedFinalState& cfs = apply<ChargedFinalState>(event, "CFS");
  if (cfs.size() < 1) vetoEvent;

  Particles particles = cfs.particlesByPt();
  Particle p_lead = particles[0];
  const double philead = p_lead.phi();
  const double pTlead = p_lead.pT();

  int tNch = 0;
  double ptSum = 0.0;
  for (const Particle& p : particles) {
    const double pT = p.pT();
    const double dPhi = deltaPhi(philead, p.phi());
    const int ir = region_index(dPhi);
    if (ir == 1) {
      ++tNch;
      ptSum += pT;
    }
  }

  const double dEtadPhi = 4.0 * PI / 3.0;

  _p[_sqs + "nch_transverse"]->fill(pTlead / GeV, tNch / dEtadPhi);
  _p[_sqs + "ptSumDen"]->fill(pTlead / GeV, ptSum / dEtadPhi);

  if (tNch > 0) _p[_sqs + "avePt"]->fill(pTlead / GeV, ptSum / tNch);
}

private:

map<string, Profile1DPtr> _p;

string _sqs = "";

};

RIVET_DECLARE_PLUGIN(CDF_2012_NOTE10874);

} ```