Rivet analyses referenceATLAS_2019_I1740909Jet fragmentation using charged particlesExperiment: ATLAS (LHC) Inspire ID: 1740909 Status: VALIDATED Authors:
Beam energies: (6500.0, 6500.0) GeV Run details:
This paper presents a measurement of quantities related to the formation of jets from high-energy quarks and gluons (fragmentation). Jets with transverse momentum 100 GeV $< p_T <$ 2.5 TeV and pseudorapidity $|\eta|<2.1$ from an integrated luminosity of 33 fb$^{-1}$ of $\sqrt{s}=$13 TeV proton-proton collisions are reconstructed with the ATLAS detector at the Large Hadron Collider. Charged-particle tracks with $p_T >$ 500 MeV and $|\eta|<2.5$ are used to probe the detailed structure of the jet. The fragmentation properties of the more forward and the more central of the two leading jets from each event are studied. The data are unfolded to correct for detector resolution and acceptance effects. Comparisons with parton shower Monte Carlo generators indicate that existing models provide a reasonable description of the data across a wide range of phase space, but there are also significant differences. Furthermore, the data are interpreted in the context of quark- and gluon-initiated jets by exploiting the rapidity dependence of the jet flavor fraction. A first measurement of the charged-particle multiplicity using model-independent jet labels (topic modeling) provides a promising alternative to traditional quark and gluon extractions using input from simulation. The simulations provide a reasonable description of the quark-like data across the jet $p_T$ range presented in this measurement, but the gluon-like data have systematically fewer charged particles than the simulations. Source code: ATLAS_2019_I1740909.cc 1#include "Rivet/Analysis.hh"
2#include "Rivet/Projections/FinalState.hh"
3#include "Rivet/Projections/VetoedFinalState.hh"
4#include "Rivet/Projections/InvisibleFinalState.hh"
5#include "Rivet/Projections/PromptFinalState.hh"
6#include "Rivet/Projections/FastJets.hh"
7
8namespace Rivet {
9
10 /// @brief jet fragmentation at 13 TeV
11 class ATLAS_2019_I1740909: public Analysis {
12 public:
13
14 RIVET_DEFAULT_ANALYSIS_CTOR(ATLAS_2019_I1740909);
15
16 /// Book cuts and projections
17 void init() {
18
19 const FinalState bare_MU(Cuts::abspid == PID::MUON);
20
21 VetoedFinalState jetinput;
22 jetinput.addVetoOnThisFinalState(bare_MU);
23 jetinput.addVetoOnThisFinalState(InvisibleFinalState());
24
25 FastJets jetpro(jetinput, JetAlg::ANTIKT, 0.4);
26 declare(jetpro, "Jets");
27
28 book(_p["nch_jetpt_F"], 1, 1, 1);
29 book(_p["nch_jetpt_C"], 2, 1, 1);
30 book(_p["nch_jetpt_B"], 9, 1, 1);
31
32 vector<double> ptbins{100., 200., 300., 400., 500., 600., 700., 800.,
33 900., 1000., 1200., 1400., 1600., 2000., 2500.};
34 for (const string& suff : vector<string>{"B", "F", "C"}) {
35 book(_h["nch_"+suff], ptbins);
36 book(_h["r_"+suff], ptbins);
37 book(_h["zeta_"+suff], ptbins);
38 book(_h["pTrel_"+suff], ptbins);
39 }
40 for (size_t idx = 0; idx < ptbins.size()-1; ++idx) {
41 dualbook(_h["nch_B"]->bin(idx+1), 13 + idx, 1, 1);
42 dualbook(_h["r_B"]->bin(idx+1), 27 + idx, 1, 1);
43 dualbook(_h["zeta_B"]->bin(idx+1), 41 + idx, 1, 1);
44 dualbook(_h["pTrel_B"]->bin(idx+1), 55 + idx, 1, 1);
45 dualbook(_h["nch_F"]->bin(idx+1), 69 + idx, 1, 1);
46 dualbook(_h["r_F"]->bin(idx+1), 83 + idx, 1, 1);
47 dualbook(_h["zeta_F"]->bin(idx+1), 97 + idx, 1, 1);
48 dualbook(_h["pTrel_F"]->bin(idx+1), 111 + idx, 1, 1);
49 dualbook(_h["nch_C"]->bin(idx+1), 125 + idx, 1, 1);
50 dualbook(_h["r_C"]->bin(idx+1), 139 + idx, 1, 1);
51 dualbook(_h["zeta_C"]->bin(idx+1), 153 + idx, 1, 1);
52 dualbook(_h["pTrel_C"]->bin(idx+1), 167 + idx, 1, 1);
53 }
54 }
55
56 void dualbook(Histo1DPtr& hist, unsigned int d, unsigned int x, unsigned int y) {
57 const string hname = mkAxisCode(d, x, y);
58 book(hist, "_aux_"+hname, refData(hname));
59 book(_s[hist.get()->basePath()], hname);
60 }
61
62 void analyze(const Event& event) {
63
64 //Init
65 double fnch=0;
66 double cnch=0;
67 double fzval=0;
68 double czval=0;
69 double frval=0;
70 double crval=0;
71 double ftval=0;
72 double ctval=0;
73
74 // Event selection
75 Jets m_goodJets = apply<JetFinder>(event, "Jets").jetsByPt(Cuts::pT > 100*GeV && Cuts::abseta < 2.1);
76 if (m_goodJets.size() < 2) vetoEvent;
77 if (fabs(1.0 - m_goodJets[0].pT()/m_goodJets[1].pT()) > 0.5) vetoEvent;
78 // Decide forward or central
79 bool check = m_goodJets[0].abseta() < m_goodJets[1].abseta();
80 int pos_f = int(check);
81 int pos_c = int(!check);
82
83 // Calculate obs, separately for central and fwd, also get bin
84 double fpt = m_goodJets[pos_f].pT();
85 double cpt = m_goodJets[pos_c].pT();
86
87 for (const Particle& p : m_goodJets[pos_f].particles()) {
88 if (p.pT() < 0.5*GeV) continue;
89 if (p.charge() != 0) {
90 ++fnch;
91
92 fzval = p.pT() / m_goodJets[pos_f].pt();
93 ftval = p.pT()*sin(p.phi()-m_goodJets[pos_f].phi());
94 frval = deltaR(m_goodJets[pos_f], p);
95
96 _h["r_F"]->fill(fpt, frval);
97 _h["r_B"]->fill(fpt, frval);
98 _h["zeta_F"]->fill(fpt, fzval);
99 _h["zeta_B"]->fill(fpt, fzval);
100 _h["pTrel_F"]->fill(fpt, ftval);
101 _h["pTrel_B"]->fill(fpt, ftval);
102 }
103 }
104
105
106 for (const Particle& p : m_goodJets[pos_c].particles()) {
107 if (p.pT() < 0.5*GeV) continue;
108 if (p.charge() != 0) {
109 ++cnch;
110 czval = p.pT() / m_goodJets[pos_c].pt();
111 ctval = p.pT()*sin(p.phi()-m_goodJets[pos_c].phi());
112 crval = deltaR(m_goodJets[pos_c], p);
113
114 _h["r_C"]->fill(cpt, crval);
115 _h["r_B"]->fill(cpt, crval);
116 _h["zeta_C"]->fill(cpt, czval);
117 _h["zeta_B"]->fill(cpt, czval);
118 _h["pTrel_C"]->fill(cpt, ctval);
119 _h["pTrel_B"]->fill(cpt, ctval);
120 }
121 }
122
123 if (fnch > 63) fnch = 63;
124 if (cnch > 63) cnch = 63;
125
126 //Fill nchg histo
127
128 _p["nch_jetpt_F"]->fill(fpt,fnch);
129 _p["nch_jetpt_C"]->fill(cpt,cnch);
130 _p["nch_jetpt_B"]->fill(fpt,fnch);
131 _p["nch_jetpt_B"]->fill(cpt,cnch);
132
133 _h["nch_F"]->fill(fpt, fnch);
134 _h["nch_C"]->fill(cpt, cnch);
135 _h["nch_B"]->fill(fpt, fnch);
136 _h["nch_B"]->fill(cpt, cnch);
137 }
138
139
140 void finalize() {
141
142 for (const string& suff : vector<string>{"B", "F", "C"}) {
143 const double num = suff=="B"? 2.0 : 1.0;
144 vector<double> sf = _h["nch_"+suff]->sumWGroup();
145 for (double& f : sf) {
146 f = safediv(num, f, 0.0);
147 }
148 scale({_h["nch_"+suff], _h["zeta_"+suff], _h["pTrel_"+suff], _h["r_"+suff]}, sf);
149 for (auto& r : _h["r_"+suff]->bins()) {
150 for (auto& b : r->bins()) {
151 b.scaleW(1.0/(2*M_PI*b.xMid()));
152 }
153 }
154 }
155
156 for (auto& hist : _h) {
157 for (auto& b : hist.second->bins()) {
158 barchart(b, _s[b.get()->basePath()]);
159 }
160 }
161
162 }
163
164 private:
165
166 map<string, Histo1DGroupPtr> _h;
167 map<string, Estimate1DPtr> _s;
168 map<string, Profile1DPtr> _p;
169 };
170
171 RIVET_DECLARE_PLUGIN(ATLAS_2019_I1740909);
172
173}
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