Rivet analyses referenceBESIII_2013_I1247675$e^+e^-\to (D^*\bar{D}^*)^\pm\pi^\mp$ for $\sqrt{s}=4.26$ GeVExperiment: BESIII (BEPC) Inspire ID: 1247675 Status: VALIDATED NOHEPDATA Authors:
Beam energies: (2.1, 2.1) GeV Run details:
Measurement of mass distributions for $e^+e^-\to (D^*\bar{D}^*)^\pm\pi^\mp$ for $\sqrt{s}=4.26$ GeV by BES. The cross section for $e^+e^-\to Z_c(4025)^\pm\pi^\mp\to (D^*\bar{D}^*)^\pm\pi^\mp$ is also measured. As there is no PDG code for the $Z_c(4025)^+ we take it to be 9044213, although this can be changed using the PID option. Source code: BESIII_2013_I1247675.cc 1// -*- C++ -*-
2#include "Rivet/Analysis.hh"
3#include "Rivet/Projections/FinalState.hh"
4#include "Rivet/Projections/UnstableParticles.hh"
5
6namespace Rivet {
7
8
9 /// @brief e+e-> Z(4025)+- pi-+
10 class BESIII_2013_I1247675 : public Analysis {
11 public:
12
13 /// Constructor
14 RIVET_DEFAULT_ANALYSIS_CTOR(BESIII_2013_I1247675);
15
16
17 /// @name Analysis methods
18 /// @{
19
20 /// Book histograms and initialise projections before the run
21 void init() {
22 // set the PDG code
23 _pid = getOption<double>("PID", 9044213);
24 // projections
25 declare(FinalState(), "FS");
26 // histograms
27 book(_sigma,1,1,1);
28 book(_h,2,1,1);
29 }
30
31
32 /// Perform the per-event analysis
33 void analyze(const Event& event) {
34 Particles fs = apply<FinalState>(event, "FS").particles();
35 Particles DD,other;
36 for (const Particle & p : fs) {
37 Particle parent=p;
38 while (!parent.parents().empty()) {
39 parent=parent.parents()[0];
40 if (parent.abspid()==413 || parent.abspid()==423) break;
41 }
42 if (parent.abspid()==413 || parent.abspid()==423) {
43 bool found=false;
44 for (const auto& D : DD) {
45 // D already in list
46 if (fuzzyEquals(D.momentum(),parent.momentum())) {
47 found=true;
48 break;
49 }
50 }
51 if(!found) DD.push_back(parent);
52 }
53 else {
54 other.push_back(p);
55 }
56 }
57 // D Dbar + charged pion
58 if (DD.size()!=2 || other.size()!=1) vetoEvent;
59 if (DD[0].pid()*DD[1].pid()>0) vetoEvent;
60 if (other[0].abspid()!=211) vetoEvent;
61 if ((DD[0].pid()==-413 && DD[1].pid()== 423 && other[0].pid()== 211) ||
62 (DD[0].pid()== 413 && DD[1].pid()==-423 && other[0].pid()==-211) ||
63 (DD[0].pid()== 423 && DD[1].pid()==-413 && other[0].pid()== 211) ||
64 (DD[0].pid()==-423 && DD[1].pid()== 413 && other[0].pid()==-211)) {
65 const double mass = (DD[0].momentum()+DD[1].momentum()).mass();
66 _h->fill(mass);
67 // parent Z+/-
68 if (DD[0].parents()[0].abspid()==_pid && DD[1].parents()[0].abspid()==_pid &&
69 fuzzyEquals(DD[0].parents()[0].mom(),DD[1].parents()[0].mom())) {
70 _sigma->fill("4.26"s);
71 }
72 }
73 }
74
75
76 /// Normalise histograms etc., after the run
77 void finalize() {
78 scale(_sigma,crossSection()/ sumOfWeights() /picobarn);
79 normalize(_h,1.,false);
80 }
81
82 /// @}
83
84
85 /// @name Histograms
86 /// @{
87 BinnedHistoPtr<string> _sigma;
88 Histo1DPtr _h;
89 int _pid;
90 /// @}
91
92
93 };
94
95
96 RIVET_DECLARE_PLUGIN(BESIII_2013_I1247675);
97
98}
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