flag
PromptPhoton:all
(default = off
)
Common switch for the group of all prompt photon processes,
as listed separately in the following.
flag
PromptPhoton:qg2qgamma
(default = off
)
Scattering q g → q gamma.
Code 201.
flag
PromptPhoton:qqbar2ggamma
(default = off
)
Scattering q qbar → g gamma.
Code 202.
flag
PromptPhoton:gg2ggamma
(default = off
)
Scattering g g → g gamma.
Note: This is a box graph. The full quark-mass dependence
in the loop leads to very complicated expressions. The current
implementation is based on assuming five massless quarks (see below),
and thus is questionable at small (pT < m_b) or large
(pT > m_t) transverse momenta.
Code 203.
flag
PromptPhoton:ffbar2gammagamma
(default = off
)
Scattering q qbar → gamma gamma.
Code 204.
flag
PromptPhoton:gg2gammagamma
(default = off
)
Scattering g g → gamma gamma.
Note: This is a box graph. The full quark-mass dependence
in the loop leads to very complicated expressions. The current
implementation is based on assuming five massless quarks (see below),
and thus is questionable at small (pT < m_b) or large
(pT > m_t) transverse momenta.
Code 205.
mode
PromptPhoton:nQuarkLoop
(default = 5
; minimum = 3
; maximum = 6
)
Number of quark flavours included in the box graphs responsible for
g g → g gamma and g g→ gamma gamma processes.
Owing to the complexity if the massive expressions, quarks are treated
as massless. The default value should be applicable in the range of
transverse momenta above the b mass but below the t one.
Note that the Z^0 and W^+- decay modes generated with the processes below only include those Standard-Model ones that are allowed for on-shell decays. Thus several other processes that receive contributions from off-shell resonances are listed separately, e.g. for top or fourth generation fermions.
There is one flag that can be used to influence the gamma^*/Z^0 structure in all the processes below where it is produced, unless otherwise stated.
mode
WeakZ0:gmZmode
(default = 0
; minimum = 0
; maximum = 2
)
Choice of full gamma^*/Z^0 structure or not in relevant
processes.
option
0 : full gamma^*/Z^0 structure,
with interference included.
option
1 : only pure gamma^* contribution.
option
2 : only pure Z^0 contribution.
Note: irrespective of the option used, the particle produced
will always be assigned code 23 for Z^0, and open decay channels
is purely dictated by what is set for the Z^0.
SigmaProcess:factorScale2 = 6
and
SigmaProcess:renormScale2 = 6
. The special phase space
cut PhaseSpace:Q2Min
may be more convenient than the
traditional pT cut; to cover the phase space edges it may also
be relevant to reduce PhaseSpace:pTHatMinDiverge
.
The processes are also included as part of the multiparton-interactions framework in hadron-hadron collisions.
flag
WeakBosonExchange:all
(default = off
)
Common switch for the group of gamma^*/Z^0
or W^+- exchange between two fermions.
flag
WeakBosonExchange:ff2ff(t:gmZ)
(default = off
)
Scattering f f' → f f' via gamma^*/Z^0
t-channel exchange, with full interference
between the gamma^* and Z^0.
Code 211.
flag
WeakBosonExchange:ff2ff(t:W)
(default = off
)
Scattering f_1 f_2 → f_3 f_4 via W^+-
t-channel exchange.
Code 212.
flag
WeakSingleBoson:all
(default = off
)
Common switch for the group of a single gamma^*/Z^0
or W^+- production.
flag
WeakSingleBoson:ffbar2gmZ
(default = off
)
Scattering f fbar → gamma^*/Z^0, with full interference
between the gamma^* and Z^0.
Code 221.
flag
WeakSingleBoson:ffbar2W
(default = off
)
Scattering f fbar' → W^+-.
Code 222.
flag
WeakSingleBoson:ffbar2ffbar(s:gm)
(default = off
)
Scattering f fbar → gamma^* → f' fbar'. Subset of
process 221, but written as a 2 → 2 process, so that
pT can be used as ordering variable, e.g. in multiparton
interactions. Hardcoded for the final state being either of the
five quark flavours or three lepton ones. Not included in the
WeakSingleBoson:all
set, but included in the
multiparton-interactions framework.
Code 223.
flag
WeakSingleBoson:ffbar2ffbar(s:gmZ)
(default = off
)
Scattering f fbar → gamma^*/Z^0 → f' fbar'. Equivalent
to process 221, but written as a 2 → 2 process, so that
pT could be used as cut or ordering variable. Final-state
flavour selection is based on the Z^0 allowed decay modes,
and the WeakZ0:gmZmode
options are implemented.
Not included in the WeakSingleBoson:all
set.
Code 224.
flag
WeakSingleBoson:ffbar2ffbar(s:W)
(default = off
)
Scattering f_1 fbar_2 → W+- → f_3 f_4. Almost equivalent
to process 222, but written as a 2 → 2 process, so that
pT could be used as cut or ordering variable. Final-state
flavour selection is based on the W allowed decay modes.
There are two simplifications relative to the implementation in
process 222. Firstly, it is not possible to set different decay modes
for the W^+ and the W^-; instead the allowed
W^+ ones will be used throughout, with charge conjugation
for the W^-. Secondly, quark mass corrections are neglected
in the decay angular distribution.
Not included in the WeakSingleBoson:all
set.
Code 225.
flag
WeakDoubleBoson:all
(default = off
)
Common switch for the group of pair production of gamma^*/Z^0
and W^+-.
flag
WeakDoubleBoson:ffbar2gmZgmZ
(default = off
)
Scattering f fbar' → gamma^*/Z^0 gamma^*/Z^0.
Code 231.
flag
WeakDoubleBoson:ffbar2ZW
(default = off
)
Scattering f fbar' → Z^0 W^+-. Note that here the
gamma^* contribution is not (currently) included.
Code 232.
flag
WeakDoubleBoson:ffbar2WW
(default = off
)
Scattering f fbar → W^+ W^-.
Code 233.
flag
WeakBosonAndParton:all
(default = off
)
Common switch for the group of production of a single electroweak
gauge boson, i.e. a gamma^*/Z^0 or a W^+-, in
association with a parton, i.e. a quark, gluon, photon or lepton.
These processes give first-order corrections to the ones in the
WeakSingleBoson
class, and both sets cannot be used
simultaneously without unphysical double-counting. The current class
should only be used to study the high-pT tail of the
gauge-boson production processes (for LHC applications at least
pT > 20 GeV), while the ones in WeakSingleBoson
should be used for inclusive production.
flag
WeakBosonAndParton:qqbar2gmZg
(default = off
)
Scattering q qbar → gamma^*/Z^0 g.
Code 241.
flag
WeakBosonAndParton:qg2gmZq
(default = off
)
Scattering q g → gamma^*/Z^0 q .
Code 242.
flag
WeakBosonAndParton:ffbar2gmZgm
(default = off
)
Scattering f fbar → gamma^*/Z^0 gamma.
Code 243.
flag
WeakBosonAndParton:fgm2gmZf
(default = off
)
Scattering f gamma → gamma^*/Z^0 f.
Code 244.
flag
WeakBosonAndParton:qqbar2Wg
(default = off
)
Scattering q qbar → W^+- g.
Code 251.
flag
WeakBosonAndParton:qg2Wq
(default = off
)
Scattering q g → W^+- q.
Code 252.
flag
WeakBosonAndParton:ffbar2Wgm
(default = off
)
Scattering f fbar → W^+- gamma.
Code 253.
flag
WeakBosonAndParton:fgm2Wf
(default = off
)
Scattering f gamma → W^+- f.
Code 254.
flag
PhotonCollision:all
(default = off
)
Common switch for the group of six processes presented below.
flag
PhotonCollision:gmgm2qqbar
(default = off
)
Scatterings gamma gamma → q qbar, where q
is a light quark (u, d, s) .
Code 261.
flag
PhotonCollision:gmgm2ccbar
(default = off
)
Scattering gamma gamma → c cbar.
Code 262.
flag
PhotonCollision:gmgm2bbbar
(default = off
)
Scattering gamma gamma → b bbar.
Code 263.
flag
PhotonCollision:gmgm2ee
(default = off
)
Scattering gamma gamma → e+ e-.
Code 264.
flag
PhotonCollision:gmgm2mumu
(default = off
)
Scattering gamma gamma → mu+ mu-.
Code 265.
flag
PhotonCollision:gmgm2tautau
(default = off
)
Scattering gamma gamma → tau+ tau-.
Code 266.
Photon-parton production processes. See comment related to PDFs above. Also relevant for direct-resolved processes in photon-photon collisions. Two instances of a given process are created when mixing processes where the direct photon can come from either side. In this case the process code in the parentheses is used when the direct photon is from side A.
flag
PhotonParton:all
(default = off
)
Common switch for the processes 271-274 (also 281-284 when relevant).
flag
PhotonParton:ggm2qqbar
(default = off
)
Scattering g gamma → q qbar, where q
is a light quark (u, d, s).
Code 271 (281).
flag
PhotonParton:ggm2ccbar
(default = off
)
Scattering g gamma → c cbar.
Code 272 (282).
flag
PhotonParton:ggm2bbbar
(default = off
)
Scattering g gamma → b bbar.
Code 273 (283).
flag
PhotonParton:qgm2qg
(default = off
)
Scattering q gamma → q g.
Code 274 (284).
flag
PhotonParton:qgm2qgm
(default = off
)
Scattering q gamma → q gamma.
Code 275 (285).