a nj cut in madgraph runcards

Hi,

In the run_card, we do have to VBF related cuts:
XETAMIN and DELTAETA that implement such cut:

C
C WBF CUTS: TWO TYPES
C
C FIRST TYPE: implemented by FM
C
C 1. FIND THE 2 HARDEST JETS
C 2. REQUIRE |RAP(J1)|>XETAMIN and |RAP(J2)|>XETAMIN
C 3. REQUIRE RAP(J1)*ETA(J2)<0
C
C SECOND TYPE : added by Simon de Visscher 1-08-2007
C
C 1. FIND THE 2 HARDEST JETS
C 2. REQUIRE |RAP(J1)-RAP(J2)|>DELTAETA
C 3. REQUIRE RAP(J1)*RAP(J2)<0
C
C

If this is not what you want, then you need to implement the cut in the file dummy_fct.f
(you can look at the file cuts.f where the two above cuts are defined)

Cheers,

Olivier

 oh, thank you. Then, WBF CUTS, XETAMIN and DELTAETA , do i need to install them? where is them?

No those cuts can be activated in the run_card.dat.

If you do not see the XETAMIN/DELTAETA in the run_card, it means that you do not have any jet at parton level for such cut to be applied. Remember that cuts in the run_card are at parton-level (i.e. before the parton shower/hadronization/jet reconstruction)

Cheers,

Olivier

but how a grammar can be used in a run_card.dat?
the content of runcard about cuts is as follow:
-------------------------------
# Standard Cuts *
#*********************************************************************
# Minimum and maximum pt's (for max, -1 means no cut) *
#*********************************************************************
 {} = pt_min_pdg ! pt cut for other particles (use pdg code). Applied on particle and anti-particle
 {} = pt_max_pdg ! pt cut for other particles (syntax e.g. {6: 100, 25: 50})
#*********************************************************************
# Minimum and maximum E's (in the center of mass frame) *
#*********************************************************************
  0.0 = ej ! minimum E for the jets
  0.0 = eb ! minimum E for the b
  0.0 = ea ! minimum E for the photons
  0.0 = el ! minimum E for the charged leptons
  -1.0 = ejmax ! maximum E for the jets
 -1.0 = ebmax ! maximum E for the b
 -1.0 = eamax ! maximum E for the photons
 -1.0 = elmax ! maximum E for the charged leptons
 {} = e_min_pdg ! E cut for other particles (use pdg code). Applied on particle and anti-particle
 {} = e_max_pdg ! E cut for other particles (syntax e.g. {6: 100, 25: 50})

#*********************************************************************
# Maximum and minimum absolute rapidity (for max, -1 means no cut) *
#*********************************************************************
 {} = eta_min_pdg ! rap cut for other particles (use pdg code). Applied on particle and anti-particle
 {} = eta_max_pdg ! rap cut for other particles (syntax e.g. {6: 2.5, 23: 5})
#*********************************************************************
# Minimum and maximum DeltaR distance *
#*********************************************************************
#*********************************************************************
# Minimum and maximum invariant mass for pairs *
#*********************************************************************
 {} = mxx_min_pdg ! min invariant mass of a pair of particles X/X~ (e.g. {6:250})
 {'default': False} = mxx_only_part_antipart ! if True the invariant mass is applied only
                       ! to pairs of particle/antiparticle and not to pairs of the same pdg codes.
#*********************************************************************
# Inclusive cuts *
#*********************************************************************
 0.0 = ptheavy ! minimum pt for at least one heavy final state
#*********************************************************************
# maximal pdg code for quark to be considered as a light jet *
# (otherwise b cuts are applied) *
#*********************************************************************
 4 = maxjetflavor ! Maximum jet pdg code
------------------------------------
here, eta or nj can not be multiplied or compared, so how to write these things?

What is your process?

Your run_card does not include any of the cuts for the jet in the final state indicating that you do not have any jet at parton level (or you did not include the associated section for the jet --which is done when the cuts is irrelevant for your process).

Cheers,

Olivier

the process is ee->tt;
the t will not produce a jet?

Since you ask for
e+ e- > t t~

MG5aMC can only apply cut on "e+", "e-", "t" and "t~".
So the cut that you mention can not be applied within our code since we do not generate the object that you mention.
So this is why you do not see the WBF cut that I was discussing above since even if you were saying those, they will not have any impact on your process at all.

To answer your question, yes the jet is going to decay into a b/W and you will have at least two bjet in your final state.
But since you do not ask MG5aMC for decaying your top, such decay will be handled by the parton-shower.
Which means that you can only do acceptance/reject of events at that level.

If instead, you would be generating
e+ e- > w+ w- b b~
then you would have the possibility to apply cut on the bjet at generation time (i.e. within our code).

Cheers,

Olivier