1 <chapter name="PYTHIA 6 Translation Table">
3 <h2>PYTHIA 6 Translation Table</h2>
5 For those more familiar with PYTHIA 6 than PYTHIA 8, here comes a table
6 that shows the approximate correspondence between some commonly used
7 variables in the two programs.The list can be expanded to meet explicit
8 needs (channel your suggestions via the Monte Carlo responsible of your
9 collaboration), but there is no question of ever providing anywhere near
12 <h3>Selecting properties of event generation</h3>
14 For PYTHIA 8 you should use the <code>pythia->readString("command")</code>
15 to give in the commands listed below, assuming that you have access to a
16 pointer <code>pythia</code> to an instance of the <code>Pythia</code> class.
18 <table cellspacing="5">
20 <tr> <th>PYTHIA 6 </th> <th>PYTHIA 8 </th>
21 <th> Comment </th> </tr>
23 <tr> <td>MSEL = 1 </td> <td>SoftQCD:minBias = on</td>
24 <td> soft and hard QCD events (for <ei>pp/pbarp</ei>)</td> </tr>
26 <tr> <td>MSEL = 2 </td> <td>SoftQCD:all = on</td>
27 <td> as above, plus elastic and diffractive (for <ei>pp/pbarp</ei>)</td> </tr>
29 <tr> <td>MSTP(61) = 0 </td> <td>PartonLevel:ISR = off</td>
30 <td> no initial-state radiation </td> </tr>
32 <tr> <td>MSTP(71) = 0 </td> <td>PartonLevel:FSR = off</td>
33 <td> no final-state radiation </td> </tr>
35 <tr> <td>MSTP(81) = 0 </td> <td>PartonLevel:MI = off</td>
36 <td> no multiple parton-parton interactions </td> </tr>
38 <tr> <td>MSTP(111) = 0 </td> <td>HadronLevel:all = off</td>
39 <td> no hadronization and no decays </td> </tr>
43 <h3>Information about generated event</h3>
45 Several PYTHIA 6 variables are stored in two places, and then both are
46 given below. For PYTHIA 8 it is assumed that you have access to a pointer
47 <code>pythia</code> to an instance of the <code>Pythia</code> class.
49 <table cellspacing="5">
51 <tr> <th>PYTHIA 6 </th> <th>PYTHIA 8 </th>
52 <th> Comment </th> </tr>
54 <tr> <td>msti(1), mint(1) </td> <td> pythia->info.code() </td>
55 <td> process ID (but changed numbering) </td> </tr>
57 <tr> <td>pari(13), vint(43) </td> <td> pythia->info.mHat() </td>
58 <td> invariant mass of the hard subprocess </td> </tr>
60 <tr> <td>pari(17), vint(47) </td> <td> pythia->info.pTHat() </td>
61 <td> transverse momentum of the hard subprocess (2 -> 2)</td> </tr>
63 <tr> <td>pari(21), vint(51) </td> <td> pythia->info.QRen() </td>
64 <td> renormalization scale Q of the hard subprocess (default definition changed)</td> </tr>
66 <tr> <td>vint(57) </td> <td> pythia->info.alphaEM()</td>
67 <td> electromagnetic coupling constant in the hard subprocess </td> </tr>
69 <tr> <td>vint(58) </td> <td> pythia->info.alphaS()</td>
70 <td> strong coupling constant in the hard subprocess </td> </tr>
72 <tr> <td>msti(15), mint(15) </td> <td> pythia->info.id1() </td>
73 <td> ID of the first incoming parton </td> </tr>
75 <tr> <td>msti(16), mint(16) </td> <td> pythia->info.id2() </td>
76 <td> ID of the second incoming parton </td> </tr>
78 <tr> <td>pari(33), vint(41) </td> <td> pythia->info.x1() </td>
79 <td> momentum fraction x of the first incoming parton </td> </tr>
81 <tr> <td>pari(34), vint(42) </td> <td> pythia->info.x2() </td>
82 <td> momentum fraction x of the second incoming parton </td> </tr>
84 <tr> <td>pari(23), vint(53) </td> <td> pythia->info.QFac() </td>
85 <td> factorization scale Q of the hard subprocess (default definition changed) </td> </tr>
87 <tr> <td>pari(29), vint(39) </td> <td> pythia->info.pdf1() </td>
88 <td> x1*f(x1) (PDF density 1) </td> </tr>
90 <tr> <td>pari(30), vint(40) </td> <td> pythia->info.pdf2() </td>
91 <td> x2*f(x2) (PDF density 2) </td> </tr>
93 <tr> <td>pari(7), vint(97) </td> <td> pythia->info.weight()</td>
94 <td> event weight (normally unity) </td> </tr>
100 <!-- Copyright (C) 2008 Torbjorn Sjostrand -->