Rivet analyses
title: LHCB_2010_I865584
LHCb differential cross section measurement of prompt $K^0_S$ production in three rapidity windows at $\sqrt{s} = 0.9$ TeV
Experiment: LHCB (LHC 900 GeV)
Inspire ID: 865584
Status: VALIDATED
Authors: - Holger Schulz - Alex Grecu
References: - Phys.Lett.B693:69-80,2010 - arXiv: 1008.3105
Beams: p+ p+
Beam energies: (450.0, 450.0)GeV
Run details: - QCD events. See paper for MC discussion.
The paper presents the cross-section and double differential cross-section measurement for prompt $K^0_S$ production in pp collisions at $\sqrt{s} = 0.9~TeV$. The data were taken during the LHCb run in December 2009 and cover a transversal momentum range from 0 to 1.6 GeV/c. The differential production cross-section is calculated for three rapidity windows $2.5 < y < 3.0$, $3.0 < y < 3.5$ and $3.5 < y < 4.0$ as well as the whole rapidity domain $2.5 < y < 4.0$.
Source code:LHCB_2010_I865584.cc
```c++ // -- C++ --
include "Rivet/Analysis.hh"
include "Rivet/Math/Constants.hh"
include "Rivet/Math/Units.hh"
include "Rivet/Projections/UnstableParticles.hh"
namespace Rivet {
class LHCB_2010_I865584 : public Analysis { public:
const double MIN_PT = 0.0001; // [GeV/c]
/// Constructor
LHCB_2010_I865584()
: Analysis("LHCB_2010_I865584"),
_mode(0),
sumKs0_all(0),
sumKs0_outup(0),
sumKs0_outdwn(0),
sum_low_pt_loss(0),
sum_high_pt_loss(0) { }
/// @name Analysis methods
/// @{
/// Book histograms and initialise projections before the run
void init() {
// only interested in Ks0 particles
declare(UnstableParticles(Cuts::pid == 310), "UFS");
if (getOption("DropPlots") == "SIG") _mode = 1;
if (getOption("DropPlots") == "D2SIG") _mode = 2;
if ((_mode & 1) == 0) { //SIG
book(_h_K0s_pt_30, 1, 1, 1);
book(_h_K0s_pt_35, 1, 1, 2);
book(_h_K0s_pt_40, 1, 1, 3);
};
if ((_mode & 2) == 0) { //D2SIG
book(_h_K0s_pt_y_30, 2, 1, 1);
book(_h_K0s_pt_y_35, 2, 1, 2);
book(_h_K0s_pt_y_40, 2, 1, 3);
};
book(_h_K0s_pt_y_all, 3, 1, 1);
book(sumKs0_30, "TMP/sumKs0_30");
book(sumKs0_35, "TMP/sumKs0_35");
book(sumKs0_40, "TMP/sumKs0_40");
}
/// Perform the per-event analysis
void analyze(const Event& event) {
const UnstableParticles& ufs = apply<UnstableParticles>(event, "UFS");
// safe to do this as container has only Ks0
sumKs0_all += ufs.particles().size();
for (const Particle& p : ufs.particles()) {
double y = p.absrapidity(); // symmetric LHCb (factor 1/2 in finalize!)
double pT = p.pT();
if (pT < MIN_PT) {
sum_low_pt_loss++; // just for debug since no inferior limit on pT
MSG_DEBUG("Small pT K^0_S: " << pT << " GeV/c.");
}
if (pT > 1.6) {
sum_high_pt_loss++;
continue; // no need to flow overflow bin
}
if ((y > 2.5) && (y < 4.0)) {
_h_K0s_pt_y_all->fill(pT);
if ((y > 2.5) && (y < 3.0)) {
if ((_mode & 2) == 0) _h_K0s_pt_y_30->fill(pT);
if ((_mode & 1) == 0) _h_K0s_pt_30->fill(pT);
sumKs0_30->fill();
}
else if ((y > 3.0) && (y < 3.5)) {
if ((_mode & 2) == 0) _h_K0s_pt_y_35->fill(pT);
if ((_mode & 1) == 0) _h_K0s_pt_35->fill(pT);
sumKs0_35->fill();
}
else if ((y > 3.5) && (y < 4.0)) {
if ((_mode & 2) == 0) _h_K0s_pt_y_40->fill(pT);
if ((_mode & 1) == 0) _h_K0s_pt_40->fill(pT);
sumKs0_40->fill();
}
}
else if (y < 2.5) {
sumKs0_outdwn++;
}
else if (y > 4.0) {
sumKs0_outup++;
}
}
}
/// Normalise histograms etc., after the run
void finalize() {
MSG_DEBUG(
"Total number Ks0: " << sumKs0_all << endl
<< "Sum of weights: " << sumOfWeights() << endl
<< "Weight Ks0 (2.5 < y < 3.0): " << sumKs0_30->sumW() << endl
<< "Weight Ks0 (3.0 < y < 3.5): " << sumKs0_35->sumW() << endl
<< "Weight Ks0 (3.5 < y < 4.0): " << sumKs0_40->sumW() << endl
<< "Nb. Ks0 (y > 4.0): " << sumKs0_outup << endl
<< "Nb. Ks0 (y < 2.5): " << sumKs0_outdwn << endl
<< "Nb. Ks0 (pT < " << (MIN_PT / MeV) << " MeV/c): " << sum_low_pt_loss << endl
<< "Nb. Ks0 (pT > 1.6 GeV/c): " << sum_high_pt_loss << endl
<< "Cross-section [mb]: " << crossSection() / picobarn / millibarn << endl
<< "Nb. events: " << numEvents());
// Compute cross-section; multiply by bin width for correct scaling
// cross-section given by Rivet in pb (symmetric LHCb!)
double xsection_factor = 0.5 * crossSection() / picobarn / sumOfWeights();
// Divide by bin area for consistent scaling, xsection in mub
scale(_h_K0s_pt_30, 0.1 * xsection_factor / microbarn);
scale(_h_K0s_pt_35, 0.1 * xsection_factor / microbarn);
scale(_h_K0s_pt_40, 0.1 * xsection_factor / microbarn);
// Already divided by dy (rapidity window width), xsection in mb
scale(_h_K0s_pt_y_30, xsection_factor / millibarn);
scale(_h_K0s_pt_y_35, xsection_factor / millibarn);
scale(_h_K0s_pt_y_40, xsection_factor / millibarn);
// factorize to phase-space volume (area)
scale(_h_K0s_pt_y_all, xsection_factor / 1.5 / 1.6 / millibarn);
}
/// @}
/// Mode switch
size_t _mode;
/// @name Histograms
/// @{
Histo1DPtr _h_K0s_pt_y_30; // histogram for 2.5 < y < 3.0 (d2sigma)
Histo1DPtr _h_K0s_pt_y_35; // histogram for 3.0 < y < 3.5 (d2sigma)
Histo1DPtr _h_K0s_pt_y_40; // histogram for 3.5 < y < 4.0 (d2sigma)
Histo1DPtr _h_K0s_pt_30; // histogram for 2.5 < y < 3.0 (sigma)
Histo1DPtr _h_K0s_pt_35; // histogram for 3.0 < y < 3.5 (sigma)
Histo1DPtr _h_K0s_pt_40; // histogram for 3.5 < y < 4.0 (sigma)
Histo1DPtr _h_K0s_pt_y_all; // histogram for 2.5 < y < 4.0 (d2sigma)
CounterPtr sumKs0_30; // Sum of weights 2.5 < y < 3.0
CounterPtr sumKs0_35; // Sum of weights 3.0 < y < 3.5
CounterPtr sumKs0_40; // Sum of weights 3.5 < y < 4.0
// Various counters mainly for debugging and comparisons between different generators
size_t sumKs0_all; // Nb of all Ks0 generated
size_t sumKs0_outup; // Nb of mesons with y > 4.0
size_t sumKs0_outdwn; // Nb of mesons with y < 2.5
size_t sum_low_pt_loss; // Nb of mesons with very low pT (indicates when units are mixed-up)
size_t sum_high_pt_loss; // Nb of mesons with pT > 1.6 GeV/c
/// @}
};
RIVET_DECLARE_ALIASED_PLUGIN(LHCB_2010_I865584, LHCB_2010_S8758301);
} ```
Aliases: - LHCB_2010_S8758301