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c6b60c38 | 1 | // main09.cc is a part of the PYTHIA event generator. |
2 | // Copyright (C) 2013 Torbjorn Sjostrand. | |
3 | // PYTHIA is licenced under the GNU GPL version 2, see COPYING for details. | |
4 | // Please respect the MCnet Guidelines, see GUIDELINES for details. | |
5 | ||
6 | // Generate a predetermined second hard interaction. | |
7 | ||
8 | #include "Pythia.h" | |
9 | ||
10 | using namespace Pythia8; | |
11 | ||
12 | int main() { | |
13 | ||
14 | // Generator. | |
15 | Pythia pythia; | |
16 | Event& event = pythia.event; | |
17 | ||
18 | // Select first hard process (just a small sample of possibilities). | |
19 | //pythia.readString("HardQCD:all = on"); | |
20 | pythia.readString("Top:all = on"); | |
21 | //pythia.readString("WeakSingleBoson:ffbar2gmZ = on"); | |
22 | //pythia.readString("WeakSingleBoson:ffbar2W = on"); | |
23 | ||
24 | // Select second hard process (complete list of options). | |
25 | pythia.readString("SecondHard:generate = on"); | |
26 | //pythia.readString("SecondHard:TwoJets = on"); | |
27 | pythia.readString("SecondHard:PhotonAndJet = on"); | |
28 | //pythia.readString("SecondHard:TwoPhotons = on"); | |
29 | //pythia.readString("SecondHard:SingleGmZ = on"); | |
30 | //pythia.readString("SecondHard:SingleW = on"); | |
31 | //pythia.readString("SecondHard:TwoBJets = on"); | |
32 | ||
33 | // Kinematics cuts, common for the two. | |
34 | pythia.readString("PhaseSpace:mHatMin = 40."); | |
35 | pythia.readString("PhaseSpace:pTHatMin = 20."); | |
36 | ||
37 | // Initialize for LHC at 8 TeV. | |
38 | pythia.readString("Beams:eCM = 8000."); | |
39 | pythia.init(); | |
40 | ||
41 | // Histogram. | |
42 | Hist pTfirst("pT first collision", 100, 0., 400.); | |
43 | Hist pTsecond("pT second collision", 100, 0., 200.); | |
44 | Hist pTdiff("pT first-second collision", 100, -100., 300.); | |
45 | Hist nMult("number of multiparton interactions", 100, -0.5, 99.5); | |
46 | Hist bMore("b enhancement factor", 100, 0., 10.); | |
47 | Hist nChg("charged multiplicity", 100, -0.5, 999.5); | |
48 | ||
49 | // Generate events. | |
50 | for (int iev = 0; iev < 1000; ++iev) { | |
51 | pythia.next(); | |
52 | ||
53 | // Histogram pT. | |
54 | double pT1 = pythia.info.pTMPI(0); | |
55 | double pT2 = pythia.info.pTMPI(1); | |
56 | pTfirst.fill( pT1 ); | |
57 | pTsecond.fill( pT2 ); | |
58 | pTdiff.fill( pT1 - pT2 ); | |
59 | ||
60 | // Histogram multiparton interactions | |
61 | double nMPI = pythia.info.nMPI(); | |
62 | nMult.fill( nMPI ); | |
63 | bMore.fill( pythia.info.enhanceMPI() ); | |
64 | ||
65 | // Histogram charged multiplicity. | |
66 | int nCharged = 0; | |
67 | for (int i = 0; i < event.size(); ++i) | |
68 | if (event[i].isFinal() && event[i].isCharged()) ++nCharged; | |
69 | nChg.fill( nCharged ); | |
70 | ||
71 | } | |
72 | ||
73 | // Compare full statistics listing with what is set in info. | |
74 | pythia.stat(); | |
75 | cout << scientific << setprecision(3) << "\n From pythia.info: sigma = " | |
76 | << pythia.info.sigmaGen() << " +- " << pythia.info.sigmaErr() | |
77 | << endl; | |
78 | ||
79 | // Print histograms. | |
80 | cout << pTfirst << pTsecond << pTdiff << nMult << bMore << nChg; | |
81 | ||
82 | // Done. | |
83 | return 0; | |
84 | } |