Rivet analyses referenceBELLE_2003_I629334$\gamma\gamma\to K^+K^-$ for centre-of-mass energies between 1.4 and 2.4 GeVExperiment: BELLE (KEKB) Inspire ID: 629334 Status: VALIDATED Authors:
Beam energies: ANY Run details:
Measurement of the differential cross section for $\gamma\gamma\to K^+K^-$ for $1.4 \text{GeV} < W < 2.4 \text{GeV}$. Both the cross section as a function of the centre-of-mass energy of the photonic collision, and the differential cross section with respect to the kaon scattering angle are measured. Source code: BELLE_2003_I629334.cc 1// -*- C++ -*-
2#include "Rivet/Analysis.hh"
3#include "Rivet/Projections/FinalState.hh"
4
5namespace Rivet {
6
7
8 /// @brief gamma gamma -> K+K-
9 class BELLE_2003_I629334 : public Analysis {
10 public:
11
12 /// Constructor
13 RIVET_DEFAULT_ANALYSIS_CTOR(BELLE_2003_I629334);
14
15
16 /// @name Analysis methods
17 ///@{
18
19 /// Book histograms and initialise projections before the run
20 void init() {
21 // Final state
22 declare(FinalState(),"FS");
23 // check CMS energy in range
24 if (sqrtS()<1.4*GeV || sqrtS()>2.4*GeV)
25 throw Error("Invalid CMS energy for BELLE_2003_I629334");
26 // bin for the angle plots
27 int ibin = (sqrtS()-1.40)/0.04;
28 book(_h_cTheta,2+ibin/4,1,ibin%4+1);
29 book(_cK, "/TMP/nK");
30 }
31
32
33 /// Perform the per-event analysis
34 void analyze(const Event& event) {
35 Particles part = apply<FinalState>(event,"FS").particles();
36 if (part.size()!=2) vetoEvent;
37 double cTheta(0.);
38 bool foundP(false),foundM(false);
39 for (const Particle& p : part) {
40 if (p.pid()==PID::KPLUS) {
41 foundP=true;
42 cTheta = abs(p.momentum().z()/p.momentum().p3().mod());
43 }
44 else if (p.pid()==PID::KMINUS)
45 foundM=true;
46 }
47 if (!foundP || !foundM) vetoEvent;
48 if (cTheta<=0.6) _cK->fill();
49 if (_h_cTheta ) _h_cTheta ->fill(cTheta);
50 }
51
52
53 /// Normalise histograms etc., after the run
54 void finalize() {
55 double fact = crossSection()/nanobarn/sumOfWeights();
56 if (_h_cTheta ) scale(_h_cTheta ,fact);
57 double sigma = _cK->val()*fact;
58 double error = _cK->err()*fact;
59 Estimate1DPtr mult;
60 book(mult, 1, 1, 1);
61 for (auto& b : mult->bins()) {
62 if (inRange(sqrtS(), b.xMin(), b.xMax())) {
63 b.set(sigma, error);
64 }
65 }
66 }
67
68 ///@}
69
70
71 /// @name Histograms
72 ///@{
73 Histo1DPtr _h_cTheta;
74 CounterPtr _cK;
75 ///@}
76
77
78 };
79
80
81 RIVET_DECLARE_PLUGIN(BELLE_2003_I629334);
82
83}
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