Dire Splitting Enhancements

  1. QCD splittings
  2. QED splittings
  3. Electroweak splittings
  4. Dark U(1) splittings
The Dire parton shower allows to weight individual splittings to allow efficient isolation and study of their impact. This can e.g. be used to increase the rate of a single splitting, and/or decrease the rate of others, thus e.g. allowing to study rare splittings. It should be noted that this can make some splittings much more frequent, at the expense of a new event weight, whose fluctuations might require larger event samples.

Nevertheless, sometimes enhancements can be useful. Dire offers the option to enhance each available splitting kernel separately. For brevity, we here only describe auxiliary parameters, then one enhancement factor, and then just list all other corresponding keywords.

parm  Enhance:pTmin   (default = -1.0)
The minimal pT value t (in GeV) of emissions below which no enhancement of emission probabilities is applied. Negative values mean that enhancements may be applied to emissions at any pT. Default value is -1.0 GeV.

parm  Enhance:Dire_fsr_qcd_1->1&21   (default = 1.0)
The (double) value with which the final-state q->qg splitting is enhanced. Note that the enhancement is compensated by an additional weight factor included in the parton shower weight, to guarantee the correct real-emission and no-emission probabilities are generated.

QCD splittings

parm  Enhance:Dire_fsr_qcd_1->21&1   (default = 1.0)
(FSR, q -> g q)

parm  Enhance:Dire_fsr_qcd_21->21&21a   (default = 1.0)
(FSR, g -> g g, 1st color structure)

parm  Enhance:Dire_fsr_qcd_21->21&21b   (default = 1.0)
(FSR, g -> g g, 2nd color structure)

parm  Enhance:Dire_fsr_qcd_21->1&1a   (default = 1.0)
(FSR, g -> q qbar, soft quark)

parm  Enhance:Dire_fsr_qcd_21->1&1b   (default = 1.0)
(FSR, g -> q qbar, soft antiquark)

parm  Enhance:Dire_fsr_qcd_1->2&1&2   (default = 1.0)
(FSR, q -> q' q qbar')

parm  Enhance:Dire_fsr_qcd_1->1&1&1   (default = 1.0)
(FSR, q -> qbar q qbar)

parm  Enhance:Dire_fsr_qcd_1->1&21_notPartial   (default = 1.0)
(FSR q -> q g, with full soft logarithms, as e.g. needed in radiation off top decay products)

parm  Enhance:Dire_fsr_qcd_21->21&21_notPartial   (default = 1.0)
(FSR g -> g g, with full soft logarithms, as e.g. needed in radiation off top decay products)

parm  Enhance:Dire_fsr_qcd_21->1&1_notPartial   (default = 1.0)
(FSR g -> q qbar, with full soft logarithms, as e.g. needed in radiation off top decay products)

parm  Enhance:Dire_fsr_qcd_1->1&21&21   (default = 1.0)
(FSR q -> q g g)

parm  Enhance:Dire_fsr_qcd_1->1&d&dbar   (default = 1.0)
(FSR q -> q d dbar, soft quark)

parm  Enhance:Dire_fsr_qcd_1->1&dbar&d   (default = 1.0)
(FSR q -> q d dbar, soft antiquark)

parm  Enhance:Dire_fsr_qcd_1->1&u&ubar   (default = 1.0)
(FSR q -> q u ubar, soft quark)

parm  Enhance:Dire_fsr_qcd_1->1&ubar&u   (default = 1.0)
(FSR q -> q u ubar, soft antiquark)

parm  Enhance:Dire_fsr_qcd_1->1&s&sbar   (default = 1.0)
(FSR q -> q s sbar, soft quark)

parm  Enhance:Dire_fsr_qcd_1->1&sbar&s   (default = 1.0)
(FSR q -> q s sbar, soft antiquark)

parm  Enhance:Dire_fsr_qcd_1->1&c&cbar   (default = 1.0)
(FSR q -> q c cbar, soft quark)

parm  Enhance:Dire_fsr_qcd_1->1&cbar&c   (default = 1.0)
(FSR q -> q c cbar, soft antiquark)

parm  Enhance:Dire_fsr_qcd_1->1&b&bbar   (default = 1.0)
(FSR q -> q b bbar, soft quark)

parm  Enhance:Dire_fsr_qcd_1->1&bbar&b   (default = 1.0)
(FSR q -> q b bbar, soft antiquark)

parm  Enhance:Dire_fsr_qcd_21->21&21&21   (default = 1.0)
(FSR g -> g g g)

parm  Enhance:Dire_fsr_qcd_21->21&d&dbar   (default = 1.0)
(FSR g -> q d dbar, soft quark)

parm  Enhance:Dire_fsr_qcd_21->21&dbar&d   (default = 1.0)
(FSR g -> g d dbar, soft antiquark)

parm  Enhance:Dire_fsr_qcd_21->21&u&ubar   (default = 1.0)
(FSR g -> g u ubar, soft quark)

parm  Enhance:Dire_fsr_qcd_21->21&ubar&u   (default = 1.0)
(FSR g -> g u ubar, soft antiquark)

parm  Enhance:Dire_fsr_qcd_21->21&s&sbar   (default = 1.0)
(FSR g -> g s sbar, soft quark)

parm  Enhance:Dire_fsr_qcd_21->21&sbar&s   (default = 1.0)
(FSR g -> g s sbar, soft antiquark)

parm  Enhance:Dire_fsr_qcd_21->21&c&cbar   (default = 1.0)
(FSR g -> g c cbar, soft quark)

parm  Enhance:Dire_fsr_qcd_21->21&cbar&c   (default = 1.0)
(FSR g -> g c cbar, soft antiquark)

parm  Enhance:Dire_fsr_qcd_21->21&b&bbar   (default = 1.0)
(FSR g -> g b bbar, soft quark)

parm  Enhance:Dire_fsr_qcd_21->21&bbar&b   (default = 1.0)
(FSR g -> g b bbar, soft antiquark)

parm  Enhance:Dire_isr_qcd_1->1&21   (default = 1.0)
(ISR q -> q g)

parm  Enhance:Dire_isr_qcd_21->1&1   (default = 1.0)
(ISR g -> q qbar)

parm  Enhance:Dire_isr_qcd_21->21&21a   (default = 1.0)
(ISR g -> g g, soft quark)

parm  Enhance:Dire_isr_qcd_21->21&21b   (default = 1.0)
(ISR g -> g g, soft antiquark)

parm  Enhance:Dire_isr_qcd_1->21&1   (default = 1.0)
(ISR q -> g q)

parm  Enhance:Dire_isr_qcd_1->2&1&2   (default = 1.0)
(ISR q -> q' q qbar')

parm  Enhance:Dire_isr_qcd_1->1&1&1   (default = 1.0)
(ISR q -> qbar q qbar)

QED splittings

parm  Enhance:Dire_fsr_qed_1->1&22   (default = 1.0)
(FSR q -> q a)

parm  Enhance:Dire_fsr_qed_1->22&1   (default = 1.0)
(FSR q -> a q)

parm  Enhance:Dire_fsr_qed_11->11&22   (default = 1.0)
(FSR l -> l a)

parm  Enhance:Dire_fsr_qed_11->22&11   (default = 1.0)
(FSR l -> a l)

parm  Enhance:Dire_fsr_qed_22->1&1a   (default = 1.0)
(FSR a -> d dbar, soft quark)

parm  Enhance:Dire_fsr_qed_22->1&1b   (default = 1.0)
(FSR a -> d dbar, soft antiquark)

parm  Enhance:Dire_fsr_qed_22->2&2a   (default = 1.0)
(FSR a -> u ubar, soft quark)

parm  Enhance:Dire_fsr_qed_22->2&2b   (default = 1.0)
(FSR a -> u ubar, soft antiquark)

parm  Enhance:Dire_fsr_qed_22->3&3a   (default = 1.0)
(FSR a -> s sbar, soft quark)

parm  Enhance:Dire_fsr_qed_22->3&3b   (default = 1.0)
(FSR a -> s sbar, soft antiquark)

parm  Enhance:Dire_fsr_qed_22->4&4a   (default = 1.0)
(FSR a -> c cbar, soft quark)

parm  Enhance:Dire_fsr_qed_22->4&4b   (default = 1.0)
(FSR a -> c cbar, soft antiquark)

parm  Enhance:Dire_fsr_qed_22->5&5a   (default = 1.0)
(FSR a -> b bbar, soft quark)

parm  Enhance:Dire_fsr_qed_22->5&5b   (default = 1.0)
(FSR a -> b bbar, soft antiquark)

parm  Enhance:Dire_fsr_qed_22->11&11a   (default = 1.0)
(FSR a -> e+ e-, soft e-)

parm  Enhance:Dire_fsr_qed_22->11&11b   (default = 1.0)
(FSR a -> e+ e-, soft e+)

parm  Enhance:Dire_fsr_qed_22->13&13a   (default = 1.0)
(FSR a -> mu+ mu-, soft mu-)

parm  Enhance:Dire_fsr_qed_22->13&13b   (default = 1.0)
(FSR a -> mu+ mu-, soft mu+)

parm  Enhance:Dire_fsr_qed_22->15&15a   (default = 1.0)
(FSR a -> tau+ tau-, soft tau-)

parm  Enhance:Dire_fsr_qed_22->15&15b   (default = 1.0)
(FSR a -> tau+ tau-, soft tau+)

parm  Enhance:Dire_fsr_qed_1->1&22_notPartial   (default = 1.0)
(FSR q -> q a, with full soft logarithms, as e.g. needed in radiation off top decay products)

parm  Enhance:Dire_fsr_qed_11->11&22_notPartial   (default = 1.0)
(FSR l -> l a, with full soft logarithms, as e.g. needed in radiation off top decay products)

parm  Enhance:Dire_isr_qed_1->1&22   (default = 1.0)
(ISR q -> q a)

parm  Enhance:Dire_isr_qed_1->22&1   (default = 1.0)
(ISR q -> a q)

parm  Enhance:Dire_isr_qed_22->1&1   (default = 1.0)
(ISR a -> q qbar)

parm  Enhance:Dire_isr_qed_11->11&22   (default = 1.0)
(ISR l -> l a)

parm  Enhance:Dire_isr_qed_11->22&11   (default = 1.0)
(FSR l -> a l)

parm  Enhance:Dire_isr_qed_22->11&11   (default = 1.0)
(FSR a -> l+ l-).

Electroweak splittings

At present, electroweak evolution is under development, so that these settings should not be touched for production for now.

parm  Enhance:Dire_fsr_ew_1->1&23   (default = 1.0)
(FSR q -> q z)

parm  Enhance:Dire_fsr_ew_1->23&1   (default = 1.0)
(FSR q -> z q)

parm  Enhance:Dire_fsr_ew_23->1&1a   (default = 1.0)
(FSR z -> q qbar, soft quark)

parm  Enhance:Dire_fsr_ew_23->1&1b   (default = 1.0)
(FSR z -> q qbar, soft antiquark)

parm  Enhance:Dire_fsr_ew_24->1&1a   (default = 1.0)
FSR w -> q qbar', soft quark)

parm  Enhance:Dire_fsr_ew_24->1&1b   (default = 1.0)
(FSR w -> q qbar', soft antiquark).

parm  Enhance:Dire_fsr_ew_24->24&22   (default = 1.0)
(FSR w -> w a).

parm  Enhance:Dire_fsr_ew_25->21&21   (default = 1.0)
(FSR h -> g g, as e.g. needed for Higgs hypothesis testing).

parm  Enhance:Dire_fsr_ew_25->22&22   (default = 1.0)
(FSR h -> a a, as e.g. needed for Higgs hypothesis testing).

Dark U(1) splittings

At present, dark photon evolution is under development, so that these settings should not be touched for production for now.

parm  Enhance:Dire_fsr_u1new_1->1&22   (default = 1.0)
(FSR q -> q aDark)

parm  Enhance:Dire_fsr_u1new_1->22&1   (default = 1.0)
(FSR q -> aDark q)

parm  Enhance:Dire_fsr_u1new_11->11&22   (default = 1.0)
(FSR l -> l aDark)

parm  Enhance:Dire_fsr_u1new_11->22&11   (default = 1.0)
(FSR l -> aDark l)

parm  Enhance:Dire_fsr_u1new_22->1&1a   (default = 1.0)
(FSR aDark -> d dbar, soft quark)

parm  Enhance:Dire_fsr_u1new_22->1&1b   (default = 1.0)
(FSR aDark -> d dbar, soft antiquark)

parm  Enhance:Dire_fsr_u1new_22->2&2a   (default = 1.0)
(FSR aDark -> u ubar, soft quark)

parm  Enhance:Dire_fsr_u1new_22->2&2b   (default = 1.0)
(FSR aDark -> u ubar, soft antiquark)

parm  Enhance:Dire_fsr_u1new_22->3&3a   (default = 1.0)
(FSR aDark -> s sbar, soft quark)

parm  Enhance:Dire_fsr_u1new_22->3&3b   (default = 1.0)
(FSR aDark -> s sbar, soft antiquark)

parm  Enhance:Dire_fsr_u1new_22->4&4a   (default = 1.0)
(FSR aDark -> c cbar, soft quark)

parm  Enhance:Dire_fsr_u1new_22->4&4b   (default = 1.0)
(FSR aDark -> c cbar, soft antiquark)

parm  Enhance:Dire_fsr_u1new_22->5&5a   (default = 1.0)
(FSR aDark -> b bbar, soft quark)

parm  Enhance:Dire_fsr_u1new_22->5&5b   (default = 1.0)
(FSR aDark -> b bbar, soft antiquark)

parm  Enhance:Dire_fsr_u1new_22->11&11a   (default = 1.0)
(FSR aDark -> e+ e-, soft e-)

parm  Enhance:Dire_fsr_u1new_22->11&11b   (default = 1.0)
(FSR aDark -> e+ e-, soft e+)

parm  Enhance:Dire_fsr_u1new_22->13&13a   (default = 1.0)
(FSR aDark -> mu+ mu-, soft mu-)

parm  Enhance:Dire_fsr_u1new_22->13&13b   (default = 1.0)
(FSR aDark -> mu+ mu-, soft mu+)

parm  Enhance:Dire_fsr_u1new_22->15&15a   (default = 1.0)
(FSR aDark -> tau+ tau-, soft tau-)

parm  Enhance:Dire_fsr_u1new_22->15&15b   (default = 1.0)
(FSR aDark -> tau+ tau-, soft tau+)

parm  Enhance:Dire_fsr_u1new_22->211&211a   (default = 1.0)
(FSR aDark -> pi+ pi-, soft pi-)

parm  Enhance:Dire_fsr_u1new_22->211&211b   (default = 1.0)
(FSR aDark -> pi+ pi-, soft pi+)

parm  Enhance:Dire_isr_u1new_1->1&22   (default = 1.0)
(ISR q -> q aDark)

parm  Enhance:Dire_isr_u1new_1->22&1   (default = 1.0)
(ISR q -> aDark a)

parm  Enhance:Dire_isr_u1new_22->1&1   (default = 1.0)
(ISR aDark -> q qbar)

parm  Enhance:Dire_isr_u1new_11->11&22   (default = 1.0)
(ISR l -> l aDark)

parm  Enhance:Dire_isr_u1new_11->22&11   (default = 1.0)
(ISR l -> aDark l)

parm  Enhance:Dire_isr_u1new_22->11&11   (default = 1.0)
(ISR aDark -> l+ l-).