Rivet analyses referenceZEUS_1999_I500267Measurement of High-$Q^2$ Neutral-Current $e^+p$ Deep Inelastic Scattering Cross-Sections at HERAExperiment: ZEUS (HERA Run I) Inspire ID: 500267 Status: VALIDATED Authors:
Beam energies: (820.0, 27.5) GeV Run details:
The $e^+p$ neutral-current deep inelastic scattering differential cross-sections $d\sigma/dQ^2$, for $Q^2$ > 400 $GeV^2$, $d\sigma/dx$ and $d\sigma/dy$, for $Q^2$ > 400, 2500 and 10000 $GeV^2$, have been measured with the ZEUS detector at HERA. The data sample of $47.7 pb^{-1}$ was collected at a center-of-mass energy of 300 GeV. The cross-section, $d\sigma/dQ^2$, falls by six orders of magnitude between $Q^2 = 400$ and $40000 GeV^2$. The predictions of the Standard Model are in very good agreement with the data. Complementing the observations of time-like $Z^0$ contributions to fermion-antifermion annihilation, the data provide direct evidence for the presence of $Z^0$ exchange in the space-like region explored by deep inelastic scattering. Source code: ZEUS_1999_I500267.cc 1// -*- C++ -*-
2#include "Rivet/Analysis.hh"
3#include "Rivet/Projections/DISKinematics.hh"
4
5
6namespace Rivet {
7
8/// @brief Measurement of High-$Q^2$ Neutral-Current in DIS
9class ZEUS_1999_I500267 : public Analysis {
10
11 public:
12 /// Constructor
13 RIVET_DEFAULT_ANALYSIS_CTOR(ZEUS_1999_I500267);
14
15 /// @name Analysis methods
16 ///@{
17
18 /// Book histograms and initialise projections before the run
19 void init() {
20
21 const DISKinematics& diskin = DISKinematics();
22 declare(diskin,"Kinematics");
23
24 book(_h_Q2, 1, 1, 1);
25 book(_h_x[0], 2, 1, 1);
26 book(_h_x[1], 3, 1, 1);
27 book(_h_x[2], 4, 1, 1);
28
29 }
30
31 /// Perform the per-event analysis
32 void analyze(const Event& event) {
33
34 /// DIS kinematics
35 const DISKinematics& dk = apply<DISKinematics>(event, "Kinematics");
36
37 double q2 = dk.Q2();
38 double x = dk.x();
39 double y = dk.y();
40
41 if (y > 0.95) vetoEvent;
42 if (q2 < 400) vetoEvent;
43 if (q2 > 400) _h_x[0]->fill(x);
44 if (q2 > 2500) _h_x[1]->fill(x);
45 if (q2 > 10000) _h_x[2]->fill(x);
46 _h_Q2->fill(q2);
47
48 }
49
50 /// Normalise histograms etc., after the run
51 void finalize() {
52 const double norm = crossSection()/picobarn/sumOfWeights();
53 scale(_h_Q2, norm);
54 scale(_h_x[0],norm);
55 scale(_h_x[1], norm);
56 scale(_h_x[2], norm);
57 }
58
59 private:
60
61 Histo1DPtr _h_Q2;
62 Histo1DPtr _h_x[3];
63 };
64
65 // The hook for the plugin system
66 RIVET_DECLARE_PLUGIN(ZEUS_1999_I500267);
67
68
69}
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