A wide selection of fundamental
and
tree
processes of the Standard Model (electroweak and strong) has been
included in PYTHIA, and slots are provided for many more, not yet
implemented. In addition, `minimum-bias'-type processes
(like elastic scattering), loop graphs, box graphs,
tree
graphs and many non-Standard Model processes are included. The
classification is not always unique. A process that proceeds only
via an
-channel state is classified as a
process
(e.g.
), but a
cross section may well have contributions from
-channel diagrams
(
obtains contributions from
). Also, in the program,
and
graphs may sometimes be convoluted with two
splittings to form effective
or
processes
(
is folded with
and
to give
).
The original classification and numbering scheme feels less relevant
today than when originally conceived. In those days, the calculation
of
or
matrix elements was sufficiently complicated
that one would wish to avoid it if at all possible, e.g. by having in
mind to define effective parton densities for all standard model
particles, such as the
. Today, the improved computational
techniques and increased computing power implies that people would be
willing to include a branching
as part of the hard
process, i.e. not try to factor it off in some approximation. With the
large top mass and large Higgs mass limits, there is also a natural
subdivision, such that the
quark is the heaviest object for which
the parton distribution concept makes sense. Therefore most of the
prepared but empty slots are likely to remain empty, or be reclaimed
for other processes.
It is possible to select a combination of subprocesses to simulate,
and also afterwards to know which subprocess was actually selected in
each event. For this purpose, all subprocesses are numbered according
to an ISUB code. The list of possible codes is given in Tables
,
,
,
,
,
,
and
. Only processes marked with a `+' sign in the first
column have been implemented in the program to date. Although
ISUB codes were originally designed in a logical fashion,
we must admit that subsequent developments of the program have tended
to obscure the structure. For instance, the process numbers for Higgs
production are spread out, in part as a consequence of the original
classification, in part because further production mechanisms have been
added one at a time, in whatever free slots could be found. At some
future date the subprocess list will therefore be re-organized.
In the thematic descriptions that follow the main tables, the
processes of interest are repeated in a more logical order. If you
want to look for a specific process, it will be easier
to find it there.
| In | No. | Subprocess | Reference | |
| + | 1 |
|
[Eic84] | |
| + | 2 |
|
[Eic84] | |
| + | 3 |
|
[Eic84] | |
| 4 |
|
|||
| + | 5 |
|
[Eic84,Cha85] | |
| 6 |
|
|||
| 7 |
|
|||
| + | 8 |
|
[Eic84,Cha85] | |
| + | 10 |
|
[Ing87a] | |
| + | 11 |
|
[Com77,Ben84,Eic84,Chi90] | |
| + | 12 |
|
[Com77,Ben84,Eic84,Chi90] | |
| + | 13 |
|
[Com77,Ben84] | |
| + | 14 |
|
[Hal78,Ben84] | |
| + | 15 |
|
[Eic84] | |
| + | 16 |
|
[Eic84] | |
| 17 |
|
|||
| + | 18 |
|
[Ber84] | |
| + | 19 |
|
[Eic84] | |
| + | 20 |
|
[Eic84,Sam91] | |
| 21 |
|
|||
| + | 22 |
|
[Eic84,Gun86] | |
| + | 23 |
|
[Eic84,Gun86] | |
| + | 24 |
|
[Ber85] | |
| + | 25 |
|
[Bar94,Gun86] | |
| + | 26 |
|
[Eic84] | |
| 27 |
|
|||
| + | 28 |
|
[Com77,Ben84] | |
| + | 29 |
|
[Hal78,Ben84] | |
| + | 30 |
|
[Eic84] | |
| + | 31 |
|
[Eic84] | |
| 32 |
|
|||
| + | 33 |
|
[Duk82] | |
| + | 34 |
|
[Duk82] | |
| + | 35 |
|
[Gab86] | |
| + | 36 |
|
[Gab86] | |
| 37 |
|
|||
| 38 |
|
|||
| 39 |
|
| In | No. | Subprocess | Reference | |
| 40 |
|
|||
| 41 |
|
|||
| 42 |
|
|||
| 43 |
|
|||
| 44 |
|
|||
| 45 |
|
|||
| 46 |
|
|||
| 47 |
|
|||
| 48 |
|
|||
| 49 |
|
|||
| 50 |
|
|||
| 51 |
|
|||
| 52 |
|
|||
| + | 53 |
|
[Com77,Ben84] | |
| + | 54 |
|
[Duk82] | |
| 55 |
|
|||
| 56 |
|
|||
| 57 |
|
|||
| + | 58 |
|
[Bar90] | |
| 59 |
|
|||
| 60 |
|
|||
| 61 |
|
|||
| 62 |
|
|||
| 63 |
|
|||
| 64 |
|
|||
| 65 |
|
|||
| 66 |
|
|||
| 67 |
|
|||
| + | 68 |
|
[Com77,Ben84] | |
| + | 69 |
|
[Kat83] | |
| + | 70 |
|
[Kun87] | |
| + | 71 |
|
[Abb87] | |
| + | 72 |
|
[Abb87] | |
| + | 73 |
|
[Dob91] | |
| 74 |
|
|||
| 75 |
|
|||
| + | 76 |
|
[Ben87b] | |
| + | 77 |
|
[Dun86,Bar90a] | |
| 78 |
|
|||
| 79 |
|
|||
| + | 80 |
|
[Bag82] |
| In | No. | Subprocess | Reference | |
| + | 81 |
|
[Com79] | |
| + | 82 |
|
[Com79] | |
| + | 83 |
|
[Dic86] | |
| + | 84 |
|
[Fon81] | |
| + | 85 |
|
[Bar90] | |
| + | 86 |
|
[Bai83] | |
| + | 87 |
|
[Gas87] | |
| + | 88 |
|
[Gas87] | |
| + | 89 |
|
[Gas87] | |
| + | 91 | elastic scattering | [Sch94] | |
| + | 92 | single diffraction ( |
[Sch94] | |
| + | 93 | single diffraction ( |
[Sch94] | |
| + | 94 | double diffraction | [Sch94] | |
| + | 95 | low- |
[Sjö87a] | |
| + | 96 | semihard QCD |
[Sjö87a] | |
| + | 99 |
|
||
| 101 |
|
|||
| + | 102 |
|
[Eic84] | |
| + | 103 |
|
[Dre89] | |
| + | 104 |
|
[Bai83] | |
| + | 105 |
|
[Bai83] | |
| + | 106 |
|
[Dre91] | |
| + | 107 |
|
[Ber81] | |
| + | 108 |
|
[Jun97] | |
| + | 110 |
|
[Ber85a] | |
| + | 111 |
|
[Ell88] | |
| + | 112 |
|
[Ell88] | |
| + | 113 |
|
[Ell88] | |
| + | 114 |
|
[Con71,Ber84,Dic88] | |
| + | 115 |
|
[Con71,Ber84,Dic88] | |
| 116 |
|
|||
| 117 |
|
|||
| 118 |
|
|||
| 119 |
|
|||
| + | 121 |
|
[Kun84] | |
| + | 122 |
|
[Kun84] | |
| + | 123 |
|
[Cah84] | |
| + | 124 |
|
[Cah84] | |
| + | 131 |
|
[Alt78] | |
| + | 132 |
|
[Alt78] | |
| + | 133 |
|
[Alt78] |
| In | No. | Subprocess | Reference | |
| + | 134 |
|
[Alt78] | |
| + | 135 |
|
[Alt78] | |
| + | 136 |
|
[Alt78] | |
| + | 137 |
|
[Bai81] | |
| + | 138 |
|
[Bai81] | |
| + | 139 |
|
[Bai81] | |
| + | 140 |
|
[Bai81] | |
| + | 141 |
|
[Alt89] | |
| + | 142 |
|
[Alt89] | |
| + | 143 |
|
[Gun87] | |
| + | 144 |
|
[Ben85a] | |
| + | 145 |
|
[Wud86] | |
| + | 146 |
|
[Bau90] | |
| + | 147 |
|
[Bau90] | |
| + | 148 |
|
[Bau90] | |
| + | 149 |
|
[Eic84,App92] | |
| + | 151 |
|
[Eic84] | |
| + | 152 |
|
[Eic84] | |
| + | 153 |
|
[Dre89] | |
| + | 156 |
|
[Eic84] | |
| + | 157 |
|
[Eic84] | |
| + | 158 |
|
[Dre89] | |
| + | 161 |
|
[Bar88] | |
| + | 162 |
|
[Hew88] | |
| + | 163 |
|
[Hew88,Eic84] | |
| + | 164 |
|
[Hew88] | |
| + | 165 |
|
[Eic84,Lan91] | |
| + | 166 |
|
[Eic84,Lan91] | |
| + | 167 |
|
[Bau90] | |
| + | 168 |
|
[Bau90] | |
| + | 169 |
|
[Bau90] | |
| + | 171 |
|
[Eic84] | |
| + | 172 |
|
[Eic84] | |
| + | 173 |
|
[Cah84] | |
| + | 174 |
|
[Cah84] | |
| + | 176 |
|
[Eic84] | |
| + | 177 |
|
[Eic84] | |
| + | 178 |
|
[Cah84] | |
| + | 179 |
|
[Cah84] | |
| + | 181 |
|
[Kun84] | |
| + | 182 |
|
[Kun84] |
| In | No. | Subprocess | Reference | |
| + | 183 |
|
[Ell88] | |
| + | 184 |
|
[Ell88] | |
| + | 185 |
|
[Ell88] | |
| + | 186 |
|
[Kun84] | |
| + | 187 |
|
[Kun84] | |
| + | 188 |
|
[Ell88] | |
| + | 189 |
|
[Ell88] | |
| + | 190 |
|
[Ell88] | |
| + | 191 |
|
[Eic96] | |
| + | 192 |
|
[Eic96] | |
| + | 193 |
|
[Eic96] | |
| + | 194 |
|
[Eic96,Lan99] | |
| + | 195 |
|
[Eic96,Lan99] | |
| + | 201 |
|
[Bar87,Daw85] | |
| + | 202 |
|
[Bar87,Daw85] | |
| + | 203 |
|
[Bar87] | |
| + | 204 |
|
[Bar87,Daw85] | |
| + | 205 |
|
[Bar87,Daw85] | |
| + | 206 |
|
[Bar87] | |
| + | 207 |
|
[Bar87,Daw85] | |
| + | 208 |
|
[Bar87,Daw85] | |
| + | 209 |
|
[Bar87] | |
| + | 210 |
|
[Daw85] | |
| + | 211 |
|
[Daw85] | |
| + | 212 |
|
[Daw85] | |
| + | 213 |
|
[Bar87,Daw85] | |
| + | 214 |
|
[Bar87,Daw85] | |
| + | 216 |
|
[Bar86a] | |
| + | 217 |
|
[Bar86a] | |
| + | 218 |
|
[Bar86a] | |
| + | 219 |
|
[Bar86a] | |
| + | 220 |
|
[Bar86a] | |
| + | 221 |
|
[Bar86a] | |
| + | 222 |
|
[Bar86a] | |
| + | 223 |
|
[Bar86a] | |
| + | 224 |
|
[Bar86a] | |
| + | 225 |
|
[Bar86a] | |
| + | 226 |
|
[Bar86b] | |
| + | 227 |
|
[Bar86b] | |
| + | 228 |
|
[Bar86b] |
| In | No. | Subprocess | Reference | |
| + | 229 |
|
[Bar86a,Bar86b] | |
| + | 230 |
|
[Bar86a,Bar86b] | |
| + | 231 |
|
[Bar86a,Bar86b] | |
| + | 232 |
|
[Bar86a,Bar86b] | |
| + | 233 |
|
[Bar86a,Bar86b] | |
| + | 234 |
|
[Bar86a,Bar86b] | |
| + | 235 |
|
[Bar86a,Bar86b] | |
| + | 236 |
|
[Bar86a,Bar86b] | |
| + | 237 |
|
[Daw85] | |
| + | 238 |
|
[Daw85] | |
| + | 239 |
|
[Daw85] | |
| + | 240 |
|
[Daw85] | |
| + | 241 |
|
[Daw85] | |
| + | 242 |
|
[Daw85] | |
| + | 243 |
|
[Daw85] | |
| + | 244 |
|
[Daw85] | |
| + | 246 |
|
[Daw85] | |
| + | 247 |
|
[Daw85] | |
| + | 248 |
|
[Daw85] | |
| + | 249 |
|
[Daw85] | |
| + | 250 |
|
[Daw85] | |
| + | 251 |
|
[Daw85] | |
| + | 252 |
|
[Daw85] | |
| + | 253 |
|
[Daw85] | |
| + | 254 |
|
[Daw85] | |
| + | 256 |
|
[Daw85] | |
| + | 258 |
|
[Daw85] | |
| + | 259 |
|
[Daw85] | |
| + | 261 |
|
[Daw85] | |
| + | 262 |
|
[Daw85] | |
| + | 263 |
|
[Daw85] | |
| + | 264 |
|
[Daw85] | |
| + | 265 |
|
[Daw85] | |
| + | 271 |
|
[Daw85] | |
| + | 272 |
|
[Daw85] | |
| + | 273 |
|
[Daw85] | |
| + | 274 |
|
[Daw85] | |
| + | 275 |
|
[Daw85] | |
| + | 276 |
|
[Daw85] | |
| + | 277 |
|
[Daw85] |
| In | No. | Subprocess | Reference | |
| + | 278 |
|
[Daw85] | |
| + | 279 |
|
[Daw85] | |
| + | 280 |
|
[Daw85] | |
| + | 281 |
|
||
| + | 282 |
|
||
| + | 283 |
|
||
| + | 284 |
|
||
| + | 285 |
|
||
| + | 286 |
|
||
| + | 287 |
|
||
| + | 288 |
|
||
| + | 289 |
|
||
| + | 290 |
|
||
| + | 291 |
|
||
| + | 292 |
|
||
| + | 293 |
|
||
| + | 294 |
|
||
| + | 295 |
|
||
| + | 296 |
|
||
| + | 297 |
|
||
| + | 298 |
|
||
| + | 299 |
|
||
| + | 300 |
|
||
| + | 301 |
|
||
| + | 341 |
|
[Hui97] | |
| + | 342 |
|
[Hui97] | |
| + | 343 |
|
[Hui97] | |
| + | 344 |
|
[Hui97] | |
| + | 345 |
|
[Hui97] | |
| + | 346 |
|
[Hui97] | |
| + | 347 |
|
[Hui97] | |
| + | 348 |
|
[Hui97] | |
| + | 349 |
|
[Hui97] | |
| + | 350 |
|
[Hui97] | |
| + | 351 |
|
[Hui97] | |
| + | 352 |
|
[Hui97] | |
| + | 353 |
|
[Eic84] | |
| + | 354 |
|
[Eic84] | |
| + | 361 |
|
[Lan99] | |
| + | 362 |
|
[Lan99] |
| In | No. | Subprocess | Reference | |
| + | 363 |
|
[Lan99] | |
| + | 364 |
|
[Lan99] | |
| + | 365 |
|
[Lan99] | |
| + | 366 |
|
[Lan99] | |
| + | 367 |
|
[Lan99] | |
| + | 368 |
|
[Lan99] | |
| + | 370 |
|
[Lan99] | |
| + | 371 |
|
[Lan99] | |
| + | 372 |
|
[Lan99] | |
| + | 373 |
|
[Lan99] | |
| + | 374 |
|
[Lan99] | |
| + | 375 |
|
[Lan99] | |
| + | 376 |
|
[Lan99] | |
| + | 377 |
|
[Lan99] | |
| + | 391 |
|
[Ran99] | |
| + | 392 |
|
[Ran99] | |
| + | 393 |
|
[Ran99,Bij01] | |
| + | 394 |
|
[Ran99,Bij01] | |
| + | 395 |
|
[Ran99,Bij01] |
In the following,
represents a fundamental fermion of flavour
, i.e.
,
,
,
,
,
,
,
,
,
,
,
,
,
,
or
. A corresponding antifermion
is denoted by
. In several cases, some classes of fermions
are explicitly excluded, since they do not couple to the
or
(no
, e.g.). When processes have only been
included for quarks, while leptons might also have been possible,
the notation
is used. A lepton is denoted by
; in a few
cases neutrinos are also lumped under this heading.
In processes where fermion masses are explicitly included in the
matrix elements, an
or
is used to denote
an arbitrary fermion or quark. Flavours appearing already in
the initial state are denoted by indices
and
, whereas new
flavours in the final state are denoted by
and
.
In supersymmetric processes, antiparticles of sfermions
are denoted by
, i.e.
rather than the more correct but
cumbersome
or
.
Charge-conjugate channels are always assumed included as well (where
separate), and processes involving a
also imply those involving
a
. Wherever
is written, it is understood that
and
interference should be included as well (with
possibilities to switch off either, if so desired). In some cases
this is not fully implemented, see further below.
Correspondingly,
denotes the complete set
(or some subset of it). Thus the notation
is only used for a photon on the mass shell.
In the last column of the tables below, references are given to works
from which formulae have been taken. Sometimes these references are to
the original works on the subject, sometimes only to the place where
the formulae are given in the most convenient or accessible form, or
where chance lead us. Apologies to all matrix-element calculators who
are not mentioned. However, remember that this is not a review article
on physics processes, but only a way for readers to know what is
actually found in the program, for better or worse. In several
instances, errata have been obtained from the authors. Often
the formulae given in the literature have been generalized to include
trivial radiative corrections, Breit-Wigner line shapes with
-dependent widths (see section
), etc.
The following sections contain some useful comments on the processes
included in the program, grouped by physics interest rather than
sequentially by ISUB or MSEL code (see
for further information on the MSEL code). The different
ISUB and MSEL codes
that can be used to simulate the different groups are given. ISUB
codes within brackets indicate the kind of processes that indirectly
involve the given physics topic, although only as part of a larger
whole. Some obvious examples, such as the possibility to produce jets
in just about any process, are not spelled out in detail.
The text at times contains information on which special switches or
parameters are of particular interest to a given process. All these
switches are described in detail in sections
and
, but
are alluded to here so as to provide a more complete picture of the
possibilities available for the different subprocesses. However, the
list of possibilities is certainly not exhausted by the text below.