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 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<JetFinder>(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 (size_t i_bin = 0; i_bin < 14; ++i_bin) {
131
132 const double sfB = _h["nch_B"+to_str(i_bin)]->sumW();
133 if (sfB) {
134 scale(_h["zeta_B"+to_str(i_bin)],2.0/sfB);
135 scale(_h["pTrel_B"+to_str(i_bin)],2.0/sfB);
136 scale(_hr["r_B"+to_str(i_bin)],2.0/sfB);
137 scale(_h["nch_B"+to_str(i_bin)], 2.0/sfB);
138 }
139
140 const double sfF = _h["nch_F"+to_str(i_bin)]->sumW();
141 if (sfF) {
142 scale(_h["zeta_F"+to_str(i_bin)],1.0/sfF);
143 scale(_h["pTrel_F"+to_str(i_bin)],1.0/sfF);
144 scale(_hr["r_F"+to_str(i_bin)],1.0/sfF);
145 scale(_h["nch_F"+to_str(i_bin)], 1.0/sfF);
146 }
147
148 const double sfC = _h["nch_C"+to_str(i_bin)]->sumW();
149 if (sfC) {
150 scale(_h["zeta_C"+to_str(i_bin)],1.0/sfC);
151 scale(_h["pTrel_C"+to_str(i_bin)],1.0/sfC);
152 scale(_hr["r_C"+to_str(i_bin)],1.0/sfC);
153 scale(_h["nch_C"+to_str(i_bin)], 1.0/sfC);
154 }
155 }
156
157 // For r only
158 /// @todo Replace with barchart()
159 for (auto& hist : _hr) {
160 for(size_t i=1; i < hist.second->numBins()+1; ++i) {
161 const double x = hist.second->bin(i).xMid();
162 const double bW = hist.second->bin(i).xWidth();
163 hist.second->bin(i).scaleW(bW/(2.0*M_PI*x));
164 }
165 }
166
167 // The rest
168 /// @todo Replace with barchart()
169 for (auto& hist : _h) {
170 for (size_t i=1; i < hist.second->numBins()+1; ++i) {
171 const double bW = hist.second->bin(i).xWidth();
172 hist.second->bin(i).scaleW(bW);
173 }
174 }
175
176 }
177
178 private:
179
180 size_t GetJetBin(const double jetpt){
181 size_t i_bin = 0;
182 if (inRange(jetpt,100,200)) i_bin=0;
183 if (inRange(jetpt,200,300)) i_bin=1;
184 if (inRange(jetpt,300,400)) i_bin=2;
185 if (inRange(jetpt,400,500)) i_bin=3;
186 if (inRange(jetpt,500,600)) i_bin=4;
187 if (inRange(jetpt,600,700)) i_bin=5;
188 if (inRange(jetpt,700,800)) i_bin=6;
189 if (inRange(jetpt,800,900)) i_bin=7;
190 if (inRange(jetpt,900,1000)) i_bin=8;
191 if (inRange(jetpt,1000,1200)) i_bin=9;
192 if (inRange(jetpt,1200,1400)) i_bin=10;
193 if (inRange(jetpt,1400,1600)) i_bin=11;
194 if (inRange(jetpt,1600,2000)) i_bin=12;
195 if (inRange(jetpt,2000,2500)) i_bin=13;
196 if(jetpt < 100) i_bin=0;
197 if(jetpt > 2500) i_bin=13;
198 return i_bin;
199 }
200
201 map<string, Histo1DPtr> _h;
202 map<string, Histo1DPtr> _hr;
203 map<string, Profile1DPtr> _p;
204 };
205
206 RIVET_DECLARE_PLUGIN(ATLAS_2019_I1740909);
207
208}
|