Rivet analyses referenceLHCB_2023_I2635083$\pi^+\pi^-$ mass distribution in $B^0_s\to\psi(2S)\pi^+\pi^-$ and $B^0_s\to\chi_{c1}\pi^+\pi^-$Experiment: LHCB (LHC) Inspire ID: 2635083 Status: VALIDATED NOHEPDATA Authors:
Beam energies: ANY Run details:
The $\pi^+\pi^-$ mass distribution in $B^0_s\to\psi(2S)\pi^+\pi^-$ and $B^0_s\to\chi_{c1}\pi^+\pi^-$ are measured. The data was extracted from the figures in the paper. There is no consensus as to the nature of the $\chi_{c1}(3872)$ $c\bar{c}$ state and therefore we taken its PDG code to be 9030443, i.e. the first unused code for an undetermined spin one $c\bar{c}$ state. This can be changed using the PID option if a different code is used by the event generator performing the simulation. Source code: LHCB_2023_I2635083.cc 1// -*- C++ -*-
2#include "Rivet/Analysis.hh"
3#include "Rivet/Projections/UnstableParticles.hh"
4#include "Rivet/Projections/DecayedParticles.hh"
5
6namespace Rivet {
7
8
9 /// @brief B_s -> psi(2S)/X(3782) pi+pi-
10 class LHCB_2023_I2635083 : public Analysis {
11 public:
12
13 /// Constructor
14 RIVET_DEFAULT_ANALYSIS_CTOR(LHCB_2023_I2635083);
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<int>("PID", 9030443);
24 // projections
25 UnstableParticles ufs = UnstableParticles(Cuts::abspid==531);
26 declare(ufs, "UFS");
27 DecayedParticles BS0(ufs);
28 BS0.addStable(100443);
29 BS0.addStable(_pid);
30 declare(BS0, "BS0");
31 // histos
32 for (unsigned int ix=0; ix<2; ++ix) {
33 book(_h[ix], 1, 1, 1+ix);
34 }
35 }
36
37
38 /// Perform the per-event analysis
39 void analyze(const Event& event) {
40 static const map<PdgId,unsigned int> mode1 = { { 211,1}, {-211,1}, { 100443,1}};
41 static const map<PdgId,unsigned int> mode2 = { { 211,1}, {-211,1}, { _pid ,1}};
42 DecayedParticles BS0 = apply<DecayedParticles>(event, "BS0");
43 for (unsigned int ix=0; ix<BS0.decaying().size(); ++ix) {
44 unsigned int imode=0;
45 if (BS0.modeMatches(ix,3,mode1)) imode=0;
46 else if (BS0.modeMatches(ix,3,mode2)) imode=1;
47 else continue;
48 const Particle& pip = BS0.decayProducts()[ix].at( 211)[0];
49 const Particle& pim = BS0.decayProducts()[ix].at(-211)[0];
50 const double mpipi = (pip.mom()+pim.mom()).mass();
51 _h[imode]->fill(mpipi);
52 }
53 }
54
55
56 /// Normalise histograms etc., after the run
57 void finalize() {
58 normalize(_h, 1.0, false);
59 }
60
61 /// @}
62
63
64 /// @name Histograms
65 /// @{
66 int _pid;
67 Histo1DPtr _h[2];
68 /// @}
69
70
71 };
72
73
74 RIVET_DECLARE_PLUGIN(LHCB_2023_I2635083);
75
76}
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