Rivet analyses
Measurement of High-$Q^2$ Neutral-Current $e^+p$ Deep Inelastic Scattering Cross-Sections at HERA
Experiment: ZEUS (HERA Run I)
Inspire ID: 500267
Status: VALIDATED
Authors: - Andrii Verbytskyi
References: - Eur.Phys.J.C 11 (1999) 427-445 - arXiv: hep-ex/9905032
Beams: p+ e+
Beam energies: (820.0, 27.5)GeV
Run details: - Inclusive high $Q^2$ DIS
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
// -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/DISKinematics.hh"
namespace Rivet {
/// @brief Measurement of High-$Q^2$ Neutral-Current in DIS
class ZEUS_1999_I500267 : public Analysis {
public:
/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(ZEUS_1999_I500267);
/// @name Analysis methods
/// @{
/// Book histograms and initialise projections before the run
void init() {
const DISKinematics& diskin = DISKinematics();
declare(diskin, "Kinematics");
book(_h_Q2, 1, 1, 1);
book(_h_x[0], 2, 1, 1);
book(_h_x[1], 3, 1, 1);
book(_h_x[2], 4, 1, 1);
}
/// Perform the per-event analysis
void analyze(const Event& event) {
/// DIS kinematics
const DISKinematics& dk = apply<DISKinematics>(event, "Kinematics");
double q2 = dk.Q2();
double x = dk.x();
double y = dk.y();
if (y > 0.95) vetoEvent;
if (q2 < 400) vetoEvent;
if (q2 > 400) _h_x[0]->fill(x);
if (q2 > 2500) _h_x[1]->fill(x);
if (q2 > 10000) _h_x[2]->fill(x);
_h_Q2->fill(q2);
}
/// Normalise histograms etc., after the run
void finalize() {
const double norm = crossSection() / picobarn / sumOfWeights();
scale(_h_Q2, norm);
scale(_h_x[0], norm);
scale(_h_x[1], norm);
scale(_h_x[2], norm);
}
private:
Histo1DPtr _h_Q2;
Histo1DPtr _h_x[3];
};
RIVET_DECLARE_PLUGIN(ZEUS_1999_I500267);
}