Negative weights for Wjj in SM at LO
Dear MG5 experts,
I'm generating Wjj in the SM (with a BSM model of mine) at LO, without parton shower, with the following syntax:
> import model SM4LQatNLO_MFV
> generate p p > l+ vl j j QCD=0 NP=0 @0
> add process p p > l- vl~ j j QCD=0 NP=0 @1
To my surprise, ~40 events out of 1e5 that I generated present a negative weight.
I'm using NNPDF30 NLO, for which central values do not seem to be forced into positive-
Do you find this normal, or might it flag some problems in my model?
Cheers,
Matteo
P.S: Here's the generation banner, let me know if you need any further info:
set group_subprocesses Auto
set ignore_
set low_mem_
set complex_mass_scheme False
set include_
set gauge unitary
set loop_optimized_
set loop_color_flows False
set max_npoint_
set default_
set max_t_for_channel 99
set zerowidth_tchannel True
set nlo_mixed_expansion True
import model sm
define p = g u c d s u~ c~ d~ s~
define j = g u c d s u~ c~ d~ s~
define l+ = e+ mu+
define l- = e- mu-
define vl = ve vm vt
define vl~ = ve~ vm~ vt~
import model SM4LQatNLO_MFV
define p = 21 2 4 1 3 -2 -4 -1 -3 5 -5 # pass to 5 flavors
define j = p
generate p p > l+ vl j j QCD=0 NP=0 @0
add process p p > l- vl~ j j QCD=0 NP=0 @1
output pp_lvjj/sm_lo
]]>
</MG5ProcCard>
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# http://
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# WARNING: This Files is generated for MADEVENT (compatibility issue)*
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# Running this in MG4 will NEVER reproduce the result of MG5*
# *
#******
#******
# Process(es) requested : mg2 input *
#******
# Begin PROCESS # This is TAG. Do not modify this line
p p > l+ vl j j @0 #Process
# Be carefull the coupling are here in MG5 convention
QCD=0
NP=0
end_coup # End the couplings input
done # this tells MG there are no more procs
# End PROCESS # This is TAG. Do not modify this line
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SM4LQatNLO_MFV
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# Renormalization and factorization scales *
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False = fixed_ren_scale ! if .true. use fixed ren scale
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# Store info for systematics studies *
# WARNING: Do not use for interference type of computation *
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systematics = systematics_program ! none, systematics [python], SysCalc [depreceted, C++]
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<slha>
#######
## PARAM_CARD AUTOMATICALY GENERATED BY MG5 ####
#######
#######
## INFORMATION FOR MASS
#######
BLOCK MASS #
6 1.720000e+02 # mt
23 9.118760e+01 # mz
25 1.250000e+02 # mh
1 0.000000e+00 # d : 0.0
2 0.000000e+00 # u : 0.0
3 0.000000e+00 # s : 0.0
4 0.000000e+00 # c : 0.0
5 0.000000e+00 # b : 0.0
11 0.000000e+00 # e- : 0.0
12 0.000000e+00 # ve : 0.0
13 0.000000e+00 # mu- : 0.0
14 0.000000e+00 # vm : 0.0
15 0.000000e+00 # ta- : 0.0
16 0.000000e+00 # vt : 0.0
21 0.000000e+00 # g : 0.0
22 0.000000e+00 # a : 0.0
24 7.982436e+01 # w+ : cmath.sqrt(
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#######
BLOCK SMEFT #
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BLOCK YUKAWA #
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#######
DECAY 6 1.508336e+00 # wt
DECAY 23 2.495200e+00 # wz
DECAY 24 2.085000e+00 # ww
DECAY 25 4.070000e-03 # wh
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DECAY 9000002 2.495200e+00 # ghz : wz
DECAY 9000003 2.085000e+00 # ghwp : ww
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2 1 # number of spin states (2s+1)
3 1 # colour rep (1: singlet, 3: triplet, 8: octet)
4 1 # particle/
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## INFORMATION FOR QNUMBERS 9000002
#######
BLOCK QNUMBERS 9000002 # ghz
1 0 # 3 times electric charge
2 1 # number of spin states (2s+1)
3 1 # colour rep (1: singlet, 3: triplet, 8: octet)
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#######
## INFORMATION FOR QNUMBERS 9000003
#######
BLOCK QNUMBERS 9000003 # ghwp
1 3 # 3 times electric charge
2 1 # number of spin states (2s+1)
3 1 # colour rep (1: singlet, 3: triplet, 8: octet)
4 1 # particle/
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Question information
- Language:
- English Edit question
- Status:
- Solved
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- Solved by:
- Olivier Mattelaer
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