Rivet analyses

title: BABAR_2022_I2120528

Cross section for $e^+e^-\to K^+K^-3\pi^0$, $K^0_SK^\pm\pi^\mp2\pi^0$ and $K^0_SK^\pm\pi^\mp\pi^+\pi^-$ between threshold and 4.5 GeV

Experiment: BABAR (PEP-II)

Inspire ID: 2120528

Status: VALIDATED NOHEPDATA

Authors: - Peter Richardson

References: - arXiv: 2207.10340

Beams: e+ e-

Beam energies: ANY

Run details: - e+e- to hadrons, KS0 and pi0 should be set stable

Cross sections for $e^+e^-\to K^+K^-3\pi^0$, $K^0_SK^\pm\pi^\mp2\pi^0$ and $K^0_SK^\pm\pi^\mp\pi^+\pi^-$ between threshold and 4.5 GeV using radiative events. The cross sections for a number of resonant contributions are also measured.

Source code:BABAR_2022_I2120528.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Projections/FinalState.hh"

include "Rivet/Projections/UnstableParticles.hh"

namespace Rivet {

/// @brief e+e- -> KK 3pi class BABAR_2022_I2120528 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(BABAR_2022_I2120528);


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

/// Book histograms and initialise projections before the run
void init() {
  // Initialise and register projections
  declare(FinalState(), "FS");
  declare(UnstableParticles(), "UFS");
  for (unsigned int ix = 0; ix < 10; ++ix) {
    book(_sigma[ix], "TMP/n" + toString(ix + 1), refData(1 + ix, 1, 1));
  }
}

void findChildren(const Particle& p, map<long, int>& nRes, int& ncount) {
  for (const Particle& child : p.children()) {
    if (child.children().empty()) {
      nRes[child.pid()] -= 1;
      --ncount;
    }
    else {
      findChildren(child, nRes, ncount);
    }
  }
}

/// Perform the per-event analysis
void analyze(const Event& event) {
  const FinalState& fs = apply<FinalState>(event, "FS");
  map<long, int> nCount;
  int ntotal(0);
  for (const Particle& p : fs.particles()) {
    nCount[p.pid()] += 1;
    ++ntotal;
  }
  // stable particles
  if (ntotal == 5) {
    // K+K- 3pi0
    if (nCount[-321] == 1 && nCount[321] == 1 && nCount[111] == 3) _sigma[0]->fill(sqrtS());
    // KS0 Kpi 2pi0
    else if (nCount[111] == 2 && nCount[310] == 1
             && ((nCount[321] == 1 && nCount[-211] == 1) || (nCount[-321] == 1 && nCount[211] == 1)))
      _sigma[1]->fill(sqrtS());
    // KS0 Kpi pi+pi-
    else if (nCount[310] == 1
             && ((nCount[321] == 1 && nCount[-211] == 2 && nCount[211] == 1)
                 || (nCount[-321] == 1 && nCount[211] == 2 && nCount[-211] == 1)))
      _sigma[2]->fill(sqrtS());
  }
  // now the resonant states
  // first K+K- eta and phi eta
  const FinalState& ufs = apply<FinalState>(event, "UFS");
  for (const Particle& p : ufs.particles(Cuts::pid == PID::ETA)) {
    if (p.children().empty()) continue;
    map<long, int> nRes = nCount;
    int ncount = ntotal;
    findChildren(p, nRes, ncount);
    bool matched1 = false;
    if (ncount == 2) {
      matched1 = true;
      for (const auto& val : nRes) {
        if (abs(val.first) == PID::KPLUS) {
          if (val.second != 1) {
            matched1 = false;
            break;
          }
        }
        else if (val.second != 0) {
          matched1 = false;
          break;
        }
      }
      if (matched1) {
        _sigma[3]->fill(sqrtS());
      }
    }
    bool matched2 = false;
    for (const Particle& p2 : ufs.particles(Cuts::pid == PID::PHI)) {
      if (p2.children().empty()) continue;
      map<long, int> nRes2 = nRes;
      int ncount2 = ncount;
      findChildren(p2, nRes2, ncount2);
      if (ncount2 != 0) continue;
      matched2 = true;
      for (const auto& val : nRes2) {
        if (val.second != 0) {
          matched2 = false;
          break;
        }
      }
      if (matched2) {
        _sigma[4]->fill(sqrtS());
        break;
      }
    }
    if (matched1 || matched2) break;
  }
  // states with a K*
  Particles Kstar = ufs.particles(Cuts::abspid == 313 or Cuts::abspid == 323);
  for (unsigned int ix = 0; ix < Kstar.size(); ++ix) {
    if (Kstar[ix].children().empty()) continue;
    map<long, int> nRes = nCount;
    int ncount = ntotal;
    findChildren(Kstar[ix], nRes, ncount);
    bool matched1 = false;
    if (ncount == 3) {
      int idother = 310;
      if (Kstar[ix].abspid() == 323) idother = -321 * (Kstar[ix].pid() / Kstar[ix].abspid());
      for (const auto& val : nRes) {
        if (val.first == idother) {
          if (val.second != 1) {
            matched1 = false;
            break;
          }
        }
        else if (val.first == PID::PI0) {
          if (val.second != 2) {
            matched1 = false;
            break;
          }
        }
        else if (val.second != 0) {
          matched1 = false;
          break;
        }
      }
      if (matched1) {
        if (Kstar[ix].abspid() == 321)
          _sigma[7]->fill(sqrtS());
        else
          _sigma[6]->fill(sqrtS());
      }
      // K*+ K*-
      bool matched2 = false;
      for (unsigned int iy = 0; iy < ix + 1; ++iy) {
        if (Kstar[iy].children().empty() || Kstar[iy].abspid() == 313
            || Kstar[iy].pid() != -Kstar[ix].pid()) {
          continue;
        }
        map<long, int> nRes2 = nRes;
        int ncount2 = ncount;
        findChildren(Kstar[iy], nRes2, ncount2);
        if (ncount2 != 1) continue;
        matched2 = true;
        for (const auto& val : nRes2) {
          if (val.first == PID::PI0) {
            if (val.second != 1) {
              matched2 = false;
              break;
            }
          }
          if (val.second != 0) {
            matched2 = false;
            break;
          }
        }
        if (matched2) {
          _sigma[5]->fill(sqrtS());
          break;
        }
      }
    }
  }
  // finally f_1
  for (const Particle& p : ufs.particles(Cuts::abspid == PID::RHOPLUS)) {
    if (p.children().empty()) continue;
    map<long, int> nRes = nCount;
    int ncount = ntotal;
    findChildren(p, nRes, ncount);
    bool matched1 = false;
    if (ncount == 3) {
      int idother = -(p.pid() / p.abspid()) * 321;
      matched1 = true;
      for (const auto& val : nRes) {
        if (val.first == PID::PI0 || val.first == idother || val.first == PID::K0S) {
          if (val.second != 1) {
            matched1 = false;
            break;
          }
        }
        else if (val.second != 0) {
          matched1 = false;
          break;
        }
      }
      if (matched1) {
        _sigma[8]->fill(sqrtS());
      }
    }
    if (matched1) break;
  }
  // finally f_1
  for (const Particle& p : ufs.particles(Cuts::pid == 20223)) {
    if (p.children().empty()) continue;
    map<long, int> nRes = nCount;
    int ncount = ntotal;
    findChildren(p, nRes, ncount);
    bool matched1 = false;
    if (ncount == 2) {
      matched1 = true;
      for (const auto& val : nRes) {
        if (abs(val.first) == PID::PIPLUS) {
          if (val.second != 1) {
            matched1 = false;
            break;
          }
        }
        else if (val.second != 0) {
          matched1 = false;
          break;
        }
      }
      if (matched1) {
        _sigma[9]->fill(sqrtS());
      }
    }
    if (matched1) break;
  }
}


/// Normalise histograms etc., after the run
void finalize() {
  const double fact = crossSection() / sumOfWeights() / nanobarn;
  for (unsigned int ix = 0; ix < 10; ++ix) {
    scale(_sigma[ix], fact);
    Estimate1DPtr tmp;
    book(tmp, 1 + ix, 1, 1);
    barchart(_sigma[ix], tmp);
  }
}

/// @}


/// @name Histograms
/// @{
Histo1DPtr _sigma[10];
/// @}

};

RIVET_DECLARE_PLUGIN(BABAR_2022_I2120528);

} ```