difference in crossection of p p > t t~ [QCD] for LO and NLO

Hi
I am trying to calculate the cross-section for the process p p > t t~ [QCD] for LO and NLO
(the measured inclusive value of cross-section is 830+-50pb)
BUT i got changed results
the value of cross-section i have got is 456.5 ± 2.2 pb for LO and 676.5 ± 3.9 pb

<LesHouchesEvents version="3.0">
<header>
<!--
#*********************************************************************
# *
# MadGraph5_aMC@NLO *
# *
# Going Beyond *
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# This file contains all the information necessary to reproduce *
# the events generated: *
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# 1. software version *
# 2. proc_card : code generation info including model *
# 3. param_card : model primary parameters in the LH format *
# 4. run_card : running parameters (collider and cuts) *
# 5. pythia_card : present only if pythia has been run *
# 6. pgs_card : present only if pgs has been run *
# 7. delphes_cards : present only if delphes has been run *
# *
# *
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<MGVersion>
3.2.0
</MGVersion>
<MG5ProcCard>
<![CDATA[
#************************************************************
#* MadGraph5_aMC@NLO *
#* *
#* * * *
#* * * * * *
#* * * * * 5 * * * * *
#* * * * * *
#* * * *
#* *
#* *
#* VERSION 3.2.0 2021-08-22 *
#* *
#* The MadGraph5_aMC@NLO Development Team - Find us at *
#* https://server06.fynu.ucl.ac.be/projects/madgraph *
#* *
#************************************************************
#* *
#* Command File for MadGraph5_aMC@NLO *
#* *
#* run as ./bin/mg5_aMC filename *
#* *
#************************************************************
set group_subprocesses Auto
set ignore_six_quark_processes False
set low_mem_multicore_nlo_generation False
set complex_mass_scheme False
set include_lepton_initiated_processes False
set gauge unitary
set loop_optimized_output True
set loop_color_flows False
set max_npoint_for_channel 0
set default_unset_couplings 99
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 loop_sm
generate p p > t t~ [QCD]
output anees
]]>
</MG5ProcCard>
<MGRunCard>
<![CDATA[
#***********************************************************************
# MadGraph5_aMC@NLO *
# *
# run_card.dat aMC@NLO *
# *
# This file is used to set the parameters of the run. *
# *
# Some notation/conventions: *
# *
# Lines starting with a hash (#) are info or comments *
# *
# mind the format: value = variable ! comment *
# *
# Some of the values of variables can be list. These can either be *
# comma or space separated. *
# *
# To display additional parameter, you can use the command: *
# update to_full *
#***********************************************************************
#
#*******************
# Running parameters
#*******************
#
#***********************************************************************
# Tag name for the run (one word) *
#***********************************************************************
  tag_1 = run_tag ! name of the run
#***********************************************************************
# Number of LHE events (and their normalization) and the required *
# (relative) accuracy on the Xsec. *
# These values are ignored for fixed order runs *
#***********************************************************************
      10000 = nevents
  -1.0 = req_acc ! Required accuracy (-1=auto determined from nevents)
  -1 = nevt_job ! Max number of events per job in event generation.
                 ! (-1= no split).
#***********************************************************************
# Output format
#***********************************************************************
  -1.0 = time_of_flight ! threshold (in mm) below which the invariant livetime is not written (-1 means not written)
  average = event_norm ! average/sum/bias. Normalization of the weight in the LHEF
#***********************************************************************
# Number of points per itegration channel (ignored for aMC@NLO runs) *
#***********************************************************************
  0.01 = req_acc_fo ! Required accuracy (-1=ignored, and use the
                     ! number of points and iter. below)
# These numbers are ignored except if req_acc_FO is equal to -1
  5000 = npoints_fo_grid ! number of points to setup grids
  4 = niters_fo_grid ! number of iter. to setup grids
  10000 = npoints_fo ! number of points to compute Xsec
  6 = niters_fo ! number of iter. to compute Xsec
#***********************************************************************
# Random number seed *
#***********************************************************************
         34 = iseed
#***********************************************************************
# Collider type and energy *
#***********************************************************************
  1 = lpp1 ! beam 1 type (0 = no PDF)
  1 = lpp2 ! beam 2 type (0 = no PDF)
  6500.0 = ebeam1 ! beam 1 energy in GeV
  6500.0 = ebeam2 ! beam 2 energy in GeV
#***********************************************************************
# PDF choice: this automatically fixes also alpha_s(MZ) and its evol. *
#***********************************************************************
  nn23nlo = pdlabel ! PDF set
  244600 = lhaid ! If pdlabel=lhapdf, this is the lhapdf number. Only
              ! numbers for central PDF sets are allowed. Can be a list;
              ! PDF sets beyond the first are included via reweighting.
#***********************************************************************
# Include the NLO Monte Carlo subtr. terms for the following parton *
# shower (HERWIG6 | HERWIGPP | PYTHIA6Q | PYTHIA6PT | PYTHIA8) *
# WARNING: PYTHIA6PT works only for processes without FSR!!!! *
#***********************************************************************
  PYTHIA8 = parton_shower
  1.0 = shower_scale_factor ! multiply default shower starting
                                  ! scale by this factor
#***********************************************************************
# Renormalization and factorization scales *
# (Default functional form for the non-fixed scales is the sum of *
# the transverse masses divided by two of all final state particles *
# and partons. This can be changed in SubProcesses/set_scales.f or via *
# dynamical_scale_choice option) *
#***********************************************************************
  False = fixed_ren_scale ! if .true. use fixed ren scale
  False = fixed_fac_scale ! if .true. use fixed fac scale
  91.118 = mur_ref_fixed ! fixed ren reference scale
  91.118 = muf_ref_fixed ! fixed fact reference scale
  -1 = dynamical_scale_choice ! Choose one (or more) of the predefined
           ! dynamical choices. Can be a list; scale choices beyond the
           ! first are included via reweighting
  1.0 = mur_over_ref ! ratio of current muR over reference muR
  1.0 = muf_over_ref ! ratio of current muF over reference muF
#***********************************************************************
# Reweight variables for scale dependence and PDF uncertainty *
#***********************************************************************
  1.0, 2.0, 0.5 = rw_rscale ! muR factors to be included by reweighting
  1.0, 2.0, 0.5 = rw_fscale ! muF factors to be included by reweighting
  True = reweight_scale ! Reweight to get scale variation using the
            ! rw_rscale and rw_fscale factors. Should be a list of
            ! booleans of equal length to dynamical_scale_choice to
            ! specify for which choice to include scale dependence.
  False = reweight_pdf ! Reweight to get PDF uncertainty. Should be a
            ! list booleans of equal length to lhaid to specify for
            ! which PDF set to include the uncertainties.
#***********************************************************************
# Store reweight information in the LHE file for off-line model- *
# parameter reweighting at NLO+PS accuracy *
#***********************************************************************
  False = store_rwgt_info ! Store info for reweighting in LHE file
#***********************************************************************
# ickkw parameter: *
# 0: No merging *
# 3: FxFx Merging - WARNING! Applies merging only at the hard-event *
# level. After showering an MLM-type merging should be applied as *
# well. See http://amcatnlo.cern.ch/FxFx_merging.htm for details. *
# 4: UNLOPS merging (with pythia8 only). No interface from within *
# MG5_aMC available, but available in Pythia8. *
# -1: NNLL+NLO jet-veto computation. See arxiv:1412.8408 [hep-ph]. *
#***********************************************************************
  0 = ickkw
#***********************************************************************
#
#***********************************************************************
# BW cutoff (M+/-bwcutoff*Gamma). Determines which resonances are *
# written in the LHE event file *
#***********************************************************************
  15.0 = bwcutoff
#***********************************************************************
# Cuts on the jets. Jet clustering is performed by FastJet. *
# - If gamma_is_j, photons are also clustered *
# - When matching to a parton shower, these generation cuts should be *
# considerably softer than the analysis cuts. *
# - More specific cuts can be specified in SubProcesses/cuts.f *
#***********************************************************************
  1.0 = jetalgo ! FastJet jet algorithm (1=kT, 0=C/A, -1=anti-kT)
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# More specific cuts can be specified in SubProcesses/cuts.f *
#***********************************************************************
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  30.0 = mll_sf ! Min inv. mass of all opp. sign same-flavor lepton pairs
#***********************************************************************
# Fermion-photon recombination parameters *
# If Rphreco=0, no recombination is performed *
#***********************************************************************
  0.1 = rphreco ! Minimum fermion-photon distance for recombination
  -1.0 = etaphreco ! Maximum abs(pseudo-rap) for photons to be recombined (a value .lt.0 means no cut)
  True = lepphreco ! Recombine photons and leptons together
  True = quarkphreco ! Recombine photons and quarks together
#***********************************************************************
# Photon-isolation cuts, according to hep-ph/9801442 *
# Not applied if gamma_is_j *
# When ptgmin=0, all the other parameters are ignored *
# More specific cuts can be specified in SubProcesses/cuts.f *
#***********************************************************************
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  -1.0 = etagamma ! Max photon abs(pseudo-rap)
  0.4 = r0gamma ! Radius of isolation code
  1.0 = xn ! n parameter of eq.(3.4) in hep-ph/9801442
  1.0 = epsgamma ! epsilon_gamma parameter of eq.(3.4) in hep-ph/9801442
  True = isoem ! isolate photons from EM energy (photons and leptons)
#***********************************************************************
# Cuts associated to MASSIVE particles identified by their PDG codes. *
# All cuts are applied to both particles and anti-particles, so use *
# POSITIVE PDG CODES only. Example of the syntax is {6 : 100} or *
# {6:100, 25:200} for multiple particles *
#***********************************************************************
  {} = pt_min_pdg ! Min pT for a massive particle
  {} = pt_max_pdg ! Max pT for a massive particle
  {} = mxx_min_pdg ! inv. mass for any pair of (anti)particles
#***********************************************************************
# Use PineAPPL to generate PDF-independent fast-interpolation grid *
# (https://zenodo.org/record/3992765#.X2EWy5MzbVo) *
#***********************************************************************
  False = pineappl ! PineAPPL switch
#***********************************************************************
]]>
</MGRunCard>
<slha>
######################################################################
## PARAM_CARD AUTOMATICALY GENERATED BY MG5 FOLLOWING UFO MODEL ####
######################################################################
## ##
## Width set on Auto will be computed following the information ##
## present in the decay.py files of the model. ##
## See arXiv:1402.1178 for more details. ##
## ##
######################################################################

###################################
## INFORMATION FOR MASS
###################################
Block mass
    5 4.700000e+00 # MB
    6 1.735000e+02 # MT
   15 1.777000e+00 # MTA
   23 9.118800e+01 # MZ
   25 1.250000e+02 # MH
## Dependent parameters, given by model restrictions.
## Those values should be edited following the
## analytical expression. MG5 ignores those values
## but they are important for interfacing the output of MG5
## to external program such as Pythia.
  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
  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
  16 0.000000e+00 # vt : 0.0
  21 0.000000e+00 # g : 0.0
  22 0.000000e+00 # a : 0.0
  24 8.041900e+01 # w+ : cmath.sqrt(MZ__exp__2/2. + cmath.sqrt(MZ__exp__4/4. - (aEW*cmath.pi*MZ__exp__2)/(Gf*sqrt__2)))

###################################
## INFORMATION FOR SMINPUTS
###################################
Block sminputs
    1 1.325070e+02 # aEWM1
    2 1.166390e-05 # Gf
    3 1.180000e-01 # aS (Note that Parameter not used if you use a PDF set)

###################################
## INFORMATION FOR YUKAWA
###################################
Block yukawa
    5 4.700000e+00 # ymb
    6 1.730000e+02 # ymt
   15 1.777000e+00 # ymtau

###################################
## INFORMATION FOR DECAY
###################################
Block QNUMBERS 82 # gh
        1 0 # 3 times electric charge
        2 1 # number of spin states (2S+1)
        3 8 # colour rep (1: singlet, 3: triplet, 8: octet)
        4 1 # Particle/Antiparticle distinction (0=own anti)
#
#*************************
# Decay widths *
#*************************
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# PDG Width
DECAY 1 0.000000e+00
#
# PDG Width
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# PDG Width
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# PDG Width
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#
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#
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#
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#
# PDG Width
DECAY 23 2.441756e+00
# BR NDA ID1 ID2 ...
   1.523658e-01 2 -1 1 # 0.37204010634479995
   1.523658e-01 2 -3 3 # 0.37204010634479995
   1.507440e-01 2 -5 5 # 0.36808006646399993
   1.188141e-01 2 -2 2 # 0.2901150415596
   1.188141e-01 2 -4 4 # 0.2901150415596
   6.793744e-02 2 -12 12 # 0.1658866761622
   6.793744e-02 2 -14 14 # 0.1658866761622
   6.793744e-02 2 -16 16 # 0.1658866761622
   3.438713e-02 2 -11 11 # 0.08396500541783998
   3.438713e-02 2 -13 13 # 0.08396500541783998
   3.430972e-02 2 -15 15 # 0.08377598908587996
#
# PDG Width
DECAY 24 2.047930e+00
# BR NDA ID1 ID2 ...
   3.333610e-01 2 -1 2 # 0.68269999273
   3.333610e-01 2 -3 4 # 0.68269999273
   1.111195e-01 2 -11 12 # 0.22756495763499998
   1.111195e-01 2 -13 14 # 0.22756495763499998
   1.110390e-01 2 -15 16 # 0.22740009927
#
# PDG Width
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</slha>
<initrwgt>
<weightgroup name='scale_variation 0 -1' combine='envelope'>
      <weight id='1001'> tag= 0 dyn= -1 muR=0.10000E+01 muF=0.10000E+01 </weight>
      <weight id='1002'> tag= 0 dyn= -1 muR=0.20000E+01 muF=0.10000E+01 </weight>
      <weight id='1003'> tag= 0 dyn= -1 muR=0.50000E+00 muF=0.10000E+01 </weight>
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      <weight id='1005'> tag= 0 dyn= -1 muR=0.20000E+01 muF=0.20000E+01 </weight>
      <weight id='1006'> tag= 0 dyn= -1 muR=0.50000E+00 muF=0.20000E+01 </weight>
      <weight id='1007'> tag= 0 dyn= -1 muR=0.10000E+01 muF=0.50000E+00 </weight>
      <weight id='1008'> tag= 0 dyn= -1 muR=0.20000E+01 muF=0.50000E+00 </weight>
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      <weight id='1012'> tag= 4 dyn= -1 muR=0.50000E+00 muF=0.10000E+01 </weight>
      <weight id='1013'> tag= 4 dyn= -1 muR=0.10000E+01 muF=0.20000E+01 </weight>
      <weight id='1014'> tag= 4 dyn= -1 muR=0.20000E+01 muF=0.20000E+01 </weight>
      <weight id='1015'> tag= 4 dyn= -1 muR=0.50000E+00 muF=0.20000E+01 </weight>
      <weight id='1016'> tag= 4 dyn= -1 muR=0.10000E+01 muF=0.50000E+00 </weight>
      <weight id='1017'> tag= 4 dyn= -1 muR=0.20000E+01 muF=0.50000E+00 </weight>
      <weight id='1018'> tag= 4 dyn= -1 muR=0.50000E+00 muF=0.50000E+00 </weight>
    </weightgroup>
    <weightgroup name='scale_variation 6 -1' combine='envelope'>
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      <weight id='1023'> tag= 6 dyn= -1 muR=0.20000E+01 muF=0.20000E+01 </weight>
      <weight id='1024'> tag= 6 dyn= -1 muR=0.50000E+00 muF=0.20000E+01 </weight>
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      <weight id='1026'> tag= 6 dyn= -1 muR=0.20000E+01 muF=0.50000E+00 </weight>
      <weight id='1027'> tag= 6 dyn= -1 muR=0.50000E+00 muF=0.50000E+00 </weight>
    </weightgroup>
</initrwgt>
<scalesfunctionalform>
muR H_T/2 := sum_i mT(i)/2, i=final state
    muF1 H_T/2 := sum_i mT(i)/2, i=final state
    muF2 H_T/2 := sum_i mT(i)/2, i=final state
    QES H_T/2 := sum_i mT(i)/2, i=final state
</scalesfunctionalform>
<montecarlomasses>
1 0.330000E+00
       2 0.330000E+00
       3 0.500000E+00
       4 0.150000E+01
       5 0.480000E+01
      11 0.510999E-03
      13 0.105658E+00
      15 0.177682E+01
      21 0.000000E+00
</montecarlomasses>
<madspin>
<![CDATA[
#************************************************************
#* MadSpin *
#* *
#* P. Artoisenet, R. Frederix, R. Rietkerk, O. Mattelaer *
#* *
#* Part of the MadGraph5_aMC@NLO Framework: *
#* The MadGraph5_aMC@NLO Development Team - Find us at *
#* https://server06.fynu.ucl.ac.be/projects/madgraph *
#* *
#* Manual: *
#* cp3.irmp.ucl.ac.be/projects/madgraph/wiki/MadSpin *
#* *
#************************************************************
#Some options (uncomment to apply)
#
# set seed 1
# set Nevents_for_max_weight 75 # number of events for the estimate of the max. weight
# set BW_cut 15 # cut on how far the particle can be off-shell
# set spinmode onshell # Use one of the madspin special mode
 set max_weight_ps_point 400 # number of PS to estimate the maximum for each event

# specify the decay for the final state particles
decay t > w+ b, w+ > all all
decay t~ > w- b~, w- > all all
#decay w+ > all all
#decay w- > all all
decay z > all all
# running the actual code
launch
]]>
</madspin>
</header>
<init>
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