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Rivet analyses reference
ALICE_2022_I1868463
$\Sigma_c^{0,+,++}$ and $\Lambda_c$ from $\Sigma_c^{0,+,++}$ analysis
Experiment: ALICE (LHC)
Inspire ID: 1868463
Status: VALIDATED
Authors:
References:
- Phys.Rev.Lett. 128 (2022) 012001, 2022
- DOI:10.1103/PhysRevLett.128.012001
- arXiv: 2106.08278
Beams: p+ p+
Beam energies: (6500.0, 6500.0) GeV
Run details:
The $p_\mathrm{T}$-differential production cross sections of prompt ${\rm D^{0}}$, ${\rm \Lambda_{c}^{+}}$, and ${\rm \Sigma_{c}^{0,++}}(2455)$ charmed hadrons are measured at midrapidity ($|y|<0.5$) in pp collisions at $\sqrt{s}=13$ TeV. This is the first measurement of ${\rm \Sigma_{c}^{0,++}}$ production in hadronic collisions. Assuming the same production yield for the three $\rm \Sigma_{c}^{0,+,++}$ isospin states, the baryon-to-meson cross section ratios $\rm \Sigma_{c}^{0,+,++}/\rm D^{0}$ and $\rm \Lambda_{c}^{+}/\rm D^{0}$ are calculated in the transverse momentum ($p_{\rm T}$) intervals $2<p_{\rm T}<12$ GeV/$c$ and $1<p_{\rm T}<24$ GeV/$c$. Values significantly larger than in $\rm e^{+}e^{-}$ collisions are observed, indicating for the first time that baryon enhancement in hadronic collisions also extends to the $\mathrm{\Sigma_{c}}$. The feed-down contribution to $\rm \Lambda_{c}^{+}$ production from $\rm \Sigma_{c}^{0,+,++}$ is also reported and is found to be larger than in $\rm e^{+}e^{-}$ collisions. The data are compared with predictions from event generators and other phenomenological models, providing a sensitive test of the different charm-hadronisation mechanisms implemented in the models.
Source code:
ALICE_2022_I1868463.cc
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100 | // -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/UnstableParticles.hh"
namespace Rivet {
/// @brief Measurement of prompt charm hadrons production in proton-proton Collisions at 13 TeV
class ALICE_2022_I1868463 : public Analysis {
public:
/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(ALICE_2022_I1868463);
/// @name Analysis methods
///@{
/// Book histograms and initialise projections before the run
void init() {
// Initialise and register projections
// The basic final-state projection:
// all final-state particles within
// the given eta acceptance
const UnstableParticles up(Cuts::absrap < 0.5);
declare(up, "up");
book(_h_D0,1,1,1);
book(_h_Lc,2,1,1);
book(_h_Sc,3,1,1);
book(_h_LcfromSc,4,1,1);
book(_h_LcD0,5,1,1);
book(_h_ScD0,6,1,1);
book(_h_LcfromScLc,7,1,1);
book(_h_D04Sc,"TMP/D04Sc",refData(3,1,1));
book(_h_Lc4Ratio, "TMP/Lc4Ratio", refData(4,1,1));
}
/// Perform the per-event analysis
void analyze(const Event& event) {
const UnstableParticles& up = apply<UnstableParticles>(event, "up");
for (const Particle& p : up.particles()) {
if(p.fromBottom())
continue;
else{
if(p.abspid()==4222 || p.abspid()==4212 || p.abspid()==4112)
_h_Sc->fill(p.pT()/GeV);
else if(p.abspid()==4122){
_h_Lc->fill(p.pT()/GeV);
_h_Lc4Ratio->fill(p.pT()/GeV);
if(p.hasAncestor(4222) || p.hasAncestor(4212) || p.hasAncestor(4112) || p.hasAncestor(-4222) || p.hasAncestor(-4212) || p.hasAncestor(-4112))
_h_LcfromSc->fill(p.pT()/GeV);
}
else if(p.abspid()==421){
_h_D0->fill(p.pT()/GeV);
_h_D04Sc->fill(p.pT()/GeV);
}
}
}
}
/// Normalise histograms etc., after the run
void finalize() {
scale(_h_D0, crossSection()/(microbarn*2*sumOfWeights()));
scale(_h_Lc, crossSection()/(microbarn*2*sumOfWeights()));
scale(_h_LcfromSc, crossSection()/(microbarn*2*sumOfWeights()));
scale(_h_Lc4Ratio, crossSection()/(microbarn*2*sumOfWeights()));
scale(_h_Sc, crossSection()/(microbarn*2*sumOfWeights()));
scale(_h_D04Sc, crossSection()/(microbarn*2*sumOfWeights())); // norm to generated cross-section in pb (after cuts)
divide(_h_Sc, _h_D04Sc, _h_ScD0);
divide(_h_Lc, _h_D0, _h_LcD0);
divide(_h_LcfromSc, _h_Lc4Ratio, _h_LcfromScLc);
}
///@}
/// @name Histograms
///@{
Histo1DPtr _h_Sc, _h_D0, _h_D04Sc, _h_LcfromSc, _h_Lc , _h_Lc4Ratio;
Scatter2DPtr _h_LcD0, _h_ScD0, _h_LcfromScLc;
///@}
};
RIVET_DECLARE_PLUGIN(ALICE_2022_I1868463);
}
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