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, FastJets::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 for (size_t i_bin = 0; i_bin < 14; ++i_bin) {
33 book(_h["nch_B"+to_str(i_bin)] , 13 + i_bin, 1, 1);
34 book(_hr["r_B"+to_str(i_bin)] , 27 + i_bin, 1, 1);
35 book(_h["zeta_B"+to_str(i_bin)] , 41 + i_bin, 1, 1);
36 book(_h["pTrel_B"+to_str(i_bin)] , 55 + i_bin, 1, 1);
37 book(_h["nch_F"+to_str(i_bin)] , 69 + i_bin, 1, 1);
38 book(_hr["r_F"+to_str(i_bin)] , 83 + i_bin, 1, 1);
39 book(_h["zeta_F"+to_str(i_bin)] , 97 + i_bin, 1, 1);
40 book(_h["pTrel_F"+to_str(i_bin)] , 111 + i_bin, 1, 1);
41 book(_h["nch_C"+to_str(i_bin)] , 125 + i_bin, 1, 1);
42 book(_hr["r_C"+to_str(i_bin)] , 139 + i_bin, 1, 1);
43 book(_h["zeta_C"+to_str(i_bin)] , 153 + i_bin, 1, 1);
44 book(_h["pTrel_C"+to_str(i_bin)] , 167 + i_bin, 1, 1);
45 }
46 }
47
48 void analyze(const Event& event) {
49
50 //Init
51 double fnch=0;
52 double cnch=0;
53 double fzval=0;
54 double czval=0;
55 double frval=0;
56 double crval=0;
57 double ftval=0;
58 double ctval=0;
59
60 // Event selection
61 Jets m_goodJets = apply<JetAlg>(event, "Jets").jetsByPt(Cuts::pT > 100*GeV && Cuts::abseta < 2.1);
62 if (m_goodJets.size() < 2) vetoEvent;
63 if (fabs(1.0 - m_goodJets[0].pT()/m_goodJets[1].pT()) > 0.5) vetoEvent;
64 // Decide forward or central
65 bool check = m_goodJets[0].abseta() < m_goodJets[1].abseta();
66 int pos_f = int(check);
67 int pos_c = int(!check);
68
69 // Calculate obs, separately for central and fwd, also get bin
70 double fpt = m_goodJets[pos_f].pT();
71 size_t f_bin = GetJetBin(fpt);
72 double cpt = m_goodJets[pos_c].pT();
73 size_t c_bin = GetJetBin(cpt);
74
75 for (const Particle& p : m_goodJets[pos_f].particles()) {
76 if (p.pT() < 0.5*GeV) continue;
77 if (p.charge() != 0) {
78 ++fnch;
79
80 fzval = p.pT() / m_goodJets[pos_f].pt();
81 ftval = p.pT()*sin(p.phi()-m_goodJets[pos_f].phi());
82 frval = deltaR(m_goodJets[pos_f], p);
83
84 _hr["r_F"+to_str(f_bin)]->fill(frval);
85 _hr["r_B"+to_str(f_bin)]->fill(frval);
86 _h["zeta_F"+to_str(f_bin)]->fill(fzval);
87 _h["zeta_B"+to_str(f_bin)]->fill(fzval);
88 _h["pTrel_F"+to_str(f_bin)]->fill(ftval);
89 _h["pTrel_B"+to_str(f_bin)]->fill(ftval);
90 }
91 }
92
93
94 for (const Particle& p : m_goodJets[pos_c].particles()) {
95 if (p.pT() < 0.5*GeV) continue;
96 if (p.charge() != 0) {
97 ++cnch;
98 czval = p.pT() / m_goodJets[pos_c].pt();
99 ctval = p.pT()*sin(p.phi()-m_goodJets[pos_c].phi());
100 crval = deltaR(m_goodJets[pos_c], p);
101
102 _hr["r_C"+to_str(c_bin)]->fill(crval);
103 _hr["r_B"+to_str(c_bin)]->fill(crval);
104 _h["zeta_C"+to_str(c_bin)]->fill(czval);
105 _h["zeta_B"+to_str(c_bin)]->fill(czval);
106 _h["pTrel_C"+to_str(c_bin)]->fill(ctval);
107 _h["pTrel_B"+to_str(c_bin)]->fill(ctval);
108 }
109 }
110
111 if (fnch > 63) fnch = 63;
112 if (cnch > 63) cnch = 63;
113
114 //Fill nchg histo
115
116 _p["nch_jetpt_F"]->fill(fpt,fnch);
117 _p["nch_jetpt_C"]->fill(cpt,cnch);
118 _p["nch_jetpt_B"]->fill(fpt,fnch);
119 _p["nch_jetpt_B"]->fill(cpt,cnch);
120
121 _h["nch_F"+to_str(f_bin)]->fill(fnch);
122 _h["nch_C"+to_str(c_bin)]->fill(cnch);
123 _h["nch_B"+to_str(f_bin)]->fill(fnch);
124 _h["nch_B"+to_str(c_bin)]->fill(cnch);
125 }
126
127
128 void finalize() {
129
130 // For r only
131 /// @todo Replace with barchart()
132 for (auto& hist : _hr) {
133 for(size_t i=0; i < hist.second->numBins(); ++i) {
134 double x = hist.second->bin(i).xMid();
135 double bW = hist.second->bin(i).xWidth();
136 hist.second->bin(i).scaleW(bW/(2.0*M_PI*x));
137 }
138 }
139
140 // The rest
141 /// @todo Replace with barchart()
142 for (auto& hist : _h) {
143 for (size_t i=0; i < hist.second->numBins(); ++i) {
144 double bW = hist.second->bin(i).xWidth();
145 hist.second->bin(i).scaleW(bW);
146 }
147 }
148
149 for (size_t i_bin = 0; i_bin < 14; ++i_bin) {
150
151 double sfB = _h["nch_B"+to_str(i_bin)]->sumW();
152 if (sfB) {
153 scale(_h["zeta_B"+to_str(i_bin)],2.0/sfB);
154 scale(_h["pTrel_B"+to_str(i_bin)],2.0/sfB);
155 scale(_hr["r_B"+to_str(i_bin)],2.0/sfB);
156 scale(_h["nch_B"+to_str(i_bin)], 2.0/sfB);
157 }
158
159 double sfF = _h["nch_F"+to_str(i_bin)]->sumW();
160 if (sfF) {
161 scale(_h["zeta_F"+to_str(i_bin)],1.0/sfF);
162 scale(_h["pTrel_F"+to_str(i_bin)],1.0/sfF);
163 scale(_hr["r_F"+to_str(i_bin)],1.0/sfF);
164 scale(_h["nch_F"+to_str(i_bin)], 1.0/sfF);
165 }
166
167 double sfC = _h["nch_C"+to_str(i_bin)]->sumW();
168 if (sfC) {
169 scale(_h["zeta_C"+to_str(i_bin)],1.0/sfC);
170 scale(_h["pTrel_C"+to_str(i_bin)],1.0/sfC);
171 scale(_hr["r_C"+to_str(i_bin)],1.0/sfC);
172 scale(_h["nch_C"+to_str(i_bin)], 1.0/sfC);
173 }
174 }
175 }
176
177 private:
178
179 size_t GetJetBin(const double jetpt){
180 size_t i_bin = 0;
181 if (inRange(jetpt,100,200)) i_bin=0;
182 if (inRange(jetpt,200,300)) i_bin=1;
183 if (inRange(jetpt,300,400)) i_bin=2;
184 if (inRange(jetpt,400,500)) i_bin=3;
185 if (inRange(jetpt,500,600)) i_bin=4;
186 if (inRange(jetpt,600,700)) i_bin=5;
187 if (inRange(jetpt,700,800)) i_bin=6;
188 if (inRange(jetpt,800,900)) i_bin=7;
189 if (inRange(jetpt,900,1000)) i_bin=8;
190 if (inRange(jetpt,1000,1200)) i_bin=9;
191 if (inRange(jetpt,1200,1400)) i_bin=10;
192 if (inRange(jetpt,1400,1600)) i_bin=11;
193 if (inRange(jetpt,1600,2000)) i_bin=12;
194 if (inRange(jetpt,2000,2500)) i_bin=13;
195 if(jetpt < 100) i_bin=0;
196 if(jetpt > 2500) i_bin=13;
197 return i_bin;
198 }
199
200 map<string, Histo1DPtr> _h;
201 map<string, Histo1DPtr> _hr;
202 map<string, Profile1DPtr> _p;
203 };
204
205 // The hook for the plugin system
206 RIVET_DECLARE_PLUGIN(ATLAS_2019_I1740909);
207
208}
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