It is possible to pass the parton systems produced by VINCIA
through PYTHIA's string hadronisation model. Normally, this should
happen automatically, according to the setting of the PYTHIA switch
HadronLevel:all
. The main parameter from the shower
side is then the phase-space contour defined by the hadronisation
cutoff.
The hadronisation cutoff, a.k.a. the infrared regularisation scale, defines the resolution scale at which the perturbative shower evolution is stopped. Thus, perturbative emissions below this scale are treated as fundmanentally unresolvable and are in effect inclusively summed over.
Important Note: when hadronisation is switched on, there is a delicate interplay between the hadronisation scale used in the shower and the parameters of the hadronisation model. Ideally, the parameters of the hadronisation model should scale as a function of the shower cutoff. This scaling does not happen automatically in current hadronisation models, such as the string model employed by PYTHIA. Instead, the parameters of the hadronisation model are tuned for one specific shower setting at a time and should be retuned if changes are made to the shower cutoff.
mode
Vincia:cutoffTypeF
(default = 1
; minimum = 0
; maximum = 2
)option
0 :
Automatically set cutoffType
equal to
evolutionType
.
option
1 : Cutoff in pT2 = sij * sjk / sijk. Note
that the arbitrary normalisation factor which is
applied to the corresponding gluon-emission evolution variable is
here absent.
option
2 : Cutoff in dipole virtuality mD2 =
min(sij,sjk). Note that the arbitrary normalisation factor which is
applied to the corresponding
gluon-emission evolution variable is here absent.
= 1 |
= 2 |
(cutoff at Vincia:cutoffScaleFF ) |
(cutoff at Vincia:cutoffScaleFF ) |
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mode
Vincia:cutoffTypeI
(default = 0
; minimum = 0
; maximum = 0
)option
0 :
Automatically set cutoffType
equal to
evolutionType
(see
initial state shower)
parm
Vincia:cutoffScaleFF
(default = 1.15
)Vincia:cutoffTypeF
.
parm
Vincia:cutoffScaleII
(default = 1.0
)parm
Vincia:cutoffScaleIF
(default = 1.1
)