Rivet analyses reference

LHCF_2023_I2658888

Measurement of the forward $\eta$ meson production rate in p-p collisions at $\sqrt{s} = 13$ TeV with the LHCf-Arm2 detector
Experiment: LHCF (LHC)
Inspire ID: 2658888
Status: VALIDATED
Authors:

Eugenio Berti
LHCf collaboration

References:

JHEP 10 (2023) 169
DOI:10.1007/JHEP10(2023)169
arXiv: 2305.06633

Beams: p+ p+
Beam energies: (6500.0, 6500.0) GeV
Run details:

Measurement of the inclusive $\eta$ meson production rate at $p_{T} < 1.10 GeV/c$ in $\sqrt{s} = 13$ TeV proton-proton collisions, expressed as a function of the Feynman variable $\x_{F} = 2 p_{Z}/sqrt(s)$.

The forward $\eta$ mesons production has been observed by the Large Hadron Collider forward (LHCf) experiment in proton-proton collision at $\sqrt{s}$ = 13 TeV. This paper presents the measurement of the inclusive production rate of $\eta$ in $p_T<$ 1.1 GeV/c, expressed as a function of the Feynman-x variable. These results are compared with the predictions of several hadronic interaction models commonly used for the modelling of the air showers produced by ultra-high energy cosmic rays. This is both the first measurement of $\eta$ mesons from LHCf and the first time a particle containing strange quarks has been observed in the forward region for high-energy collisions. These results will provide a powerful constraint on hadronic interaction models for the purpose of improving the understanding of the processes underlying the air showers produced in the Earth atmosphere by ultra-energetic cosmic rays.

Source code: LHCF_2023_I2658888.cc

 1// -*- C++ -*-
 2#include "Rivet/Analysis.hh"
 3#include "Rivet/Projections/Beam.hh"
 4#include "Rivet/Projections/UnstableParticles.hh"
 5
 6namespace Rivet {
 7
 8  /// @brief Measurement of forward neutron(+ antineutron) production in proton-proton Collisions at 13 TeV
 9  class LHCF_2023_I2658888 : public Analysis {
10  public:
11
12    /// Constructor
13    RIVET_DEFAULT_ANALYSIS_CTOR(LHCF_2023_I2658888);
14
15    /// @name Analysis methods
16    //@{
17
18    /// Book histograms and initialise projections before the run
19    void init() {
20
21      // Initialise and register projections
22      declare(UnstableFinalState(), "UFS");
23
24      // Book histograms
25      book(_h_eta_xf, 1, 1, 1);
26
27    }
28
29    /// Perform the per-event analysis
30    void analyze(const Event& event) {
31
32      const UnstableFinalState &ufs = apply<UnstableFinalState> (event, "UFS");
33
34      for (const Particle& p: ufs.particles() ) {
35        // select eta meson
36        if(p.abspid() != PID::ETA) continue;
37        // select pt range
38        const double pt = abs(p.pT()/GeV);
39        if(pt >= 1.10) continue; // fill considering both LHCf (Arm1 and Arm2) sides
40        // compute xf variable
41        const double pz = abs(p.pz()/GeV);
42        const double ss = sqrtS()/GeV;
43        const double xf = 2.*pz/ss;
44
45        _h_eta_xf->fill( xf, xf );
46      }
47
48    }
49
50    /// Normalise histograms etc., after the run
51    void finalize() {
52
53      const double sumWeights = 2.*sumOfWeights(); // scale considering the LHCf Arm2 side alone
54
55      scale(_h_eta_xf, 1./(sumWeights)); // scale to production rate
56
57    }
58    //@}
59
60  private:
61
62    /// @name Histograms
63    //@{
64    Histo1DPtr _h_eta_xf;
65    //@}
66
67  };
68
69  // The hook for the plugin system
70  RIVET_DECLARE_PLUGIN(LHCF_2023_I2658888);
71
72}