MG5_aMC tutoria
NLO:
How
to?
Part 2: NLO

Celine Degrande, Rikkert Frederix,
Olivier Mattelaer, Marco Zar
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NLO Tutorials• Part 1: xed-order computations• Part 2: event-generation and parton shower• Part 3: Spin correlations at NLO

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Iwate Collider School 20242

tt ̄ production at NLO
Part 1: Fixed orde
• Learn the syntax• > tutorial aMCatNLO• Generate the code for tt ̄ production at NL• Compute the LO and NLO cross-section (run at xed order• Select the analysis analysis_HwU_pp_ttx.o in the
FO_analyse_card to generate histograms(need GnuPlot installed• In the NLO histograms, which of these variables are describedat the NLO? pT(t), pT(tt),̄ y(t) M(tt),̄ Δɸ(tt ̄• What are the histograms with muR=… muF=… for?

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Solution
Part• Learn the syntax• > tutorial NLO• Generate the code for tt ̄ production at NL• > generate p p > t t~ [QCD

The current model sm does not allow to generate loop corrections of type QCD.
MG5_aMC now loads 'loop_sm'.
import model loop_sm. . .
INFO: Generating FKS-subtracted matrix elements for born process: g g > t t~ [ QCD ] (1 / 9)
. . .

• > output my_ttbar_nl• Compute the LO and NLO cross-sectio• > launch

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Solution
Part• Learn the syntax

INFO: ***************************************************************W E L C O M E to M A D G R A P H 5**
a M C @ N L O
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* * * * 5 * * * *
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The current model sm
allow to2.2.1
generate loop correctionsof type QCD.
* does notVERSION
2014-09-25*
MG5_aMC now loads 'loop_sm'.
**
import model loop_sm*
The MadGraph5_aMC@NLO Development Team - Find us at
*
. . .
*
http://amcatnlo.cern.ch*
INFO: Generating FKS-subtracted
matrixelements
forbornprocess:
g
g
>
t
t~
[
QCD
*
* ] (1 / 9)
. . .
*Type 'help' for in-line help.
***************************************************************
launch auto
The following switches determine which operations are executed:
1 Perturbative order of the calculation:order=NLO
2 Fixed order (no event generation and no MC@[N]LO matching):
fixed_order=OFF
3 Shower the generated events:
shower=ON
4 Decay particles with the MadSpin module:
madspin=OFF
Either type the switch number (1 to 4) to change its default setting,or set any switch explicitly (e.g. type 'order=LO' at the prompt)
Type '0', 'auto', 'done' or just press enter when you are done.
[0, 1, 2, 3, 4, auto, done, order=LO, order=NLO, ... ][60s to answer]• > tutorial NLO• Generate the code for tt ̄ production at NL• > generate p p > t t~ [QCD
• > output my_ttbar_nl• Compute the LO and NLO cross-sectio• > launch> fixed_order=ON> order=LO (for LO run)

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SolutionPart
syntax• Learn the
INFO:

INFO: ***************************************************************W E L C O M E to M A D G R A P H 5**
a M C @ N L O** Final results and run summary:
*
*
*
*
*
Process p p > t t~ [QCD]
*
*
* *
*
*
Run
at
p-p
collider
(6500
+
6500
GeV)
*
* * * * 5 * * * **Totalcross-section:
6.871e+02+5.9e+00
pb
*
*
* *
*
*
uncertainty: +9.7%* Ren. and fac. scale** -11.7%***
The current modelsm
does results
notVERSION
allowofto2.2.1
generatetype QCD.
* The
*
INFO:
this
run loopand corrections
the HwU2014-09-25
andofGnuPlot
MG5_aMC now loads'loop_sm'.
* with the plots have been saved in /Users/marcozaro/ *files
import model loop_sm*
The MadGraph5_aMC@NLO Development Team - Find us at*
Physics/MadGraph/2.2.3new/my_tt_nlo_qcd/Events/run_01. . .
*http://amcatnlo.cern.ch*
INFO: Generating FKS-subtracted
matrixelements
forbornprocess:
g
g
>
t
t~
[
QCD
*
* ] (1 / 9)
INFO:
. . .
*
Type 'help' for in-line help.
*
Finalresultsandrunsummary:**
Process p p > t t~ [QCD]************************************************************
Run atp-p collider (6500 + 6500 GeV)
launchauto
TheTotalfollowing
switches determine
which operations
arepb
executed:cross-section:
4.622e+02+- 2.2e+00
1 Ren.
Perturbative
the calculation:order=NLO
and fac.orderscaleofuncertainty:+29.8% -22.3%
2 Fixed order (no event generation and no MC@[N]LO matching):
fixed_order=OFF
3 Shower the generated events:
shower=ON
INFO: The results of this run and the HwU and GnuPlot
4 Decay particles with the MadSpin module:
madspin=OFF
files Eitherwith the
plots
have
been
saved
in
/Users/marcozaro/
type the switch number (1 to 4) to change its default setting,Physics/MadGraph/2.2.3new/my_tt_nlo_qcd/Events/run_02_LO
or set any switch explicitly (e.g. type 'order=LO' at the prompt)
Type '0', 'auto', 'done' or just press enter when you are done.
[0, 1, 2, 3, 4, auto, done, order=LO, order=NLO, ... ][60s to answer]• > tutorial NLO• Generate the code for tt ̄ production at NL• > generate p p > t t~ [QCD
• > output my_ttbar_nl• Compute the LO and NLO cross-sectio• > launch> fixed_order=ON> order=LO (for LO run)

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SolutionPart• Select the analysis analysis_HwU_pp_ttx in the
FO_analyse_card to generate histogram• > launch my_ttbar_nl

The following switches determine which operations are executed:
1 Perturbative order of the calculation:order=NLO
2 Fixed order (no event generation and no MC@[N]LO matching):
fixed_order=ON
3 Shower the generated events:
shower=OFF
4 Decay particles with the MadSpin module:
madspin=OFF
Either type the switch number (1 to 4) to change its default setting,or set any switch explicitly (e.g. type 'order=LO' at the prompt)
Type '0', 'auto', 'done' or just press enter when you are done.
[0, 1, 2, 3, 4, auto, done, order=LO, order=NLO, ... ][60s to answer]>
INFO: will run in mode: NLO
Do you want to edit a card (press enter to bypass editing)?
1 / param: param_card.dat
2 / run: run_card.dat
3 / FO_analyse : FO_analyse_card.dat
you can also
- enter the path to a valid card or banner.
- use the 'set' command to modify a parameter directly.
The set option works only for param_card and run_card.

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######################################################################### This file contains the settings for analyses to be linked to aMC@NLO# fixed order runs. Analyse files are meant to be put (or linked)# inside <PROCDIR>/FixedOrderAnalysis/ (<PROCDIR> is the name of the# exported process directory). See the# <PROCDIR>/FixedOrderAnalysis/analysis_template.f file for details on# how to write your own analysis.
########################################################################## Analysis format. Can either be 'topdrawer', 'root', 'HwU' or 'none'.
# When choosing HwU, it comes with a GnuPlot wrapper. When choosing# topdrawer, the histogramming package 'dbook.f' is included in the# code, while when choosing root the 'rbook_fe8.f' and 'rbook_be8.cc'# are included. If 'none' is chosen, all the other entries below have# to be set empty.
FO_ANALYSIS_FORMAT = HwU# switches determine which operations are executed:
The following# Needed(FastJet is already linked):
1 Perturbative
orderextra-librariesof the calculation:order=NLO
FO_EXTRALIBS=
2 Fixed order (no event generation and no MC@[N]LO matching):
fixed_order=ON# generated events:
3 Shower theshower=OFF#(Absolute)
path
to
the
extra
libraries.
Directorynames
shouldbe
4 Decay particles with the MadSpin module:
madspin=OFF#
separatedbywhitespaces.
Either type the switch number (1 to 4) to change its default setting,=or set anyFO_EXTRAPATHS
switch explicitly(e.g. type 'order=LO' at the prompt)
Type '0', #'auto', 'done' or just press enter when you are done.
# (Absolute)
path order=LO,
to the dirs
containing
needed by the[0, 1, 2, 3,
4, auto, done,order=NLO,...header][60s files
to answer]#
libraries(e.g.
C++
headerfiles):>
FO_INCLUDEPATHS
INFO: will run
in mode: NLO =Do you want #to edit a card (press enter to bypass editing)?
analysis (to be put in the <PROCDIR>/FixedOrderAnalysis/
1 / param # User's: param_card.dat#
directory).
Please use .o as extension and white spaces to separate
2 / run: run_card.dat# files.
3 / FO_analyse: FO_analyse_card.dat
FO_ANALYSE = analysis_td_template.o
you can also
# path to a valid card or banner.
- enter the- use the# 'set' command to modify a parameter directly.
When linking
withforroot,
the following
settings are a working
The set##option
works only
param_card
and run_card.
## example on lxplus (CERN). When using this, comment out the lines## above and replace <PATH_TO_ROOT> with the physical path to root,## e.g. /afs/cern.ch/sw/lcg/app/releases/ROOT/5.34.11/x86_64-slc6-gcc46-dbg/root/#FO_ANALYSIS_FORMAT = root
#FO_EXTRALIBS = Core Cint Hist Matrix MathCore RIO dl Thread#FO_EXTRAPATHS = <PATH_TO_ROOT>/lib#FO_INCLUDEPATHS = <PATH_TO_ROOT>/include#FO_ANALYSE = analysis_root_template.oSolutionPart• Select the analysis analysis_HwU_pp_ttx in the
FO_analyse_card to generate histogram• > launch my_ttbar_nl

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######################################################################### This file contains the settings for analyses to be linked to aMC@NLO# fixed order runs. Analyse files are meant to be put (or linked)# inside <PROCDIR>/FixedOrderAnalysis/ (<PROCDIR> is the name of the# exported process directory). See the# <PROCDIR>/FixedOrderAnalysis/analysis_template.f file for details on# how to write your own analysis.
########################################################################## Analysis format. Can either be 'topdrawer', 'root', 'HwU' or 'none'.
# When choosing HwU, it comes with a GnuPlot wrapper. When choosing# topdrawer, the histogramming package 'dbook.f' is included in the# code, while when choosing root the 'rbook_fe8.f' and 'rbook_be8.cc'# are included. If 'none' is chosen, all the other entries below have# to be set empty.
FO_ANALYSIS_FORMAT = HwU# switches determine which operations are executed:
The following# Needed(FastJet is already linked):
1 Perturbative
orderextra-librariesof the calculation:order=NLO
FO_EXTRALIBS=
2 Fixed order (no event generation and no MC@[N]LO matching):
fixed_order=ON# generated events:
3 Shower theshower=OFF#(Absolute)
path
to
the
extra
libraries.
Directorynames
shouldbe
4 Decay particles with the MadSpin module:
madspin=OFF#
separatedbywhitespaces.
Either type the switch number (1 to 4) to change its default setting,=or set anyFO_EXTRAPATHS
switch explicitly(e.g. type 'order=LO' at the prompt)
Type '0', #'auto', 'done' or just press enter when you are done.
# (Absolute)
path order=LO,
to the dirs
containing
needed by the[0, 1, 2, 3,
4, auto, done,order=NLO,...header][60s files
to answer]#
libraries(e.g.
C++
headerfiles):>
FO_INCLUDEPATHS
INFO: will run
in mode: NLO =Do you want #to edit a card (press enter to bypass editing)?
analysis (to be put in the <PROCDIR>/FixedOrderAnalysis/
1 / param # User's: param_card.dat#
directory).
Please use .o as extension and white spaces to separate
2 / run: run_card.dat# files.
3 / FO_analyse: FO_analyse_card.dat
FO_ANALYSE = analysis_td_template.oanalysis_HwU_pp_ttx.oyou can also
# path to a valid card or banner.
- enter the- use the# 'set' command to modify a parameter directly.
When linking
withforroot,
the following
settings are a working
The set##option
works only
param_card
and run_card.
## example on lxplus (CERN). When using this, comment out the lines## above and replace <PATH_TO_ROOT> with the physical path to root,## e.g. /afs/cern.ch/sw/lcg/app/releases/ROOT/5.34.11/x86_64-slc6-gcc46-dbg/root/#FO_ANALYSIS_FORMAT = root
#FO_EXTRALIBS = Core Cint Hist Matrix MathCore RIO dl Thread#FO_EXTRAPATHS = <PATH_TO_ROOT>/lib#FO_INCLUDEPATHS = <PATH_TO_ROOT>/include#FO_ANALYSE = analysis_root_template.oSolutionPart• Select the analysis analysis_HwU_pp_ttx in the
FO_analyse_card to generate histogram• > launch my_ttbar_nl

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Solution• The HwU (Histogram with Uncertainties) format##& xmin & xmax & central value & dy & delta_mu_min @aux & delta_mu_max @aux & muR=1.00 muF=1.00 & muR=1.00 muF=2.00 &muR=1.00 muF=0.50 & muR=2.00 muF=1.00 & muR=2.00 muF=2.00 & muR=2.00 muF=0.50 & muR=0.50 muF=1.00 & muR=0.50 muF=2.00 &muR=0.50 muF=0.50<histogram> 50 "tt pt |X_AXIS@LIN |Y_AXIS@LOG"+0.0000000e+00+2.0000000e+00-1.0242367e+03+2.5047252e+01 -1.7206530e+03-9.0715087e+02-1.1432407e+03-6.8421704e+02-6.0160203e+02-7.6882229e+02-1.7206530e+03+2.0000000e+00+4.0000000e+00+4.9088904e+02+2.0297264e+01 +3.4493531e+02+4.5019210e+02+5.3086979e+02+3.7613186e+02+3.4493531e+02+4.0679297e+02+7.1188196e+02+4.0000000e+00+6.0000000e+00+2.2787754e+02+2.3122314e+01 +1.5999659e+02+2.0857157e+02+2.4714205e+02+1.7482611e+02+1.5999659e+02+1.8963760e+02+3.3086836e+02+6.0000000e+00+8.0000000e+00+1.7671803e+02+9.5392210e+00 +1.2453269e+02+1.6227348e+02+1.9111959e+02+1.3562893e+02+1.2453269e+02+1.4669918e+02+2.5575724e+02+8.0000000e+00+1.0000000e+01+1.2311654e+02+7.1903869e+00 +8.6399100e+01+1.1261446e+02+1.3369767e+02+9.4461506e+01+8.6399100e+01+1.0258866e+02+1.7898773e+02+1.0000000e+01+1.2000000e+01+7.8022445e+01+1.0748137e+01 +5.4873577e+01+7.1570742e+01+8.4452355e+01+5.9823787e+01+5.4873577e+01+6.4760050e+01+1.1315020e+02+1.2000000e+01+1.4000000e+01+6.1770611e+01+3.2903213e+00 +4.3437593e+01

Marco Zaro, 21-06-2022

6-6.0160203e+02-1.5496422e+03-1.0242367e+03-1.3802509e+03+7.1188196e+02+6.5832080e+02+4.9088904e+02+6.0377117e+02+3.3086836e+02+3.0513912e+02+2.2787754e+02+2.7932554e+02+2.5575724e+02+2.3651862e+02+1.7671803e+02+2.1720764e+02+1.7898773e+02+1.6483914e+02+1.2311654e+02+1.5078780e+02+1.1315020e+02+1.0454718e+02+7.8022445e+01+9.5909144e+01+8.9537046e+01+6.1770611e+01

Solution
tt pt
tt pt,
1 scale variation

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SolutionPart• In the NLO histograms, which of these variables are describedat the NLO? pT(t), pT(tt),̄ y(t) M(tt),̄ Δɸ(tt ̄• Some of these variables are trivial at LO, because of 2→2
kinematic• t and t ̄ are always back to backd /d(tt̄) = (d /dpT (tt̄) = (pT⇡)
0)• pT(tt)̄ and Δɸ(tt)̄ are non-trivial if the cross-section is at leastat NLO: they are effectively described with LO accurac• The other variables are described at NLO

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SolutionPart• What are the histograms with muR=… muF=… for• QCD master formula
XZ(pp ! tt̄) =or bette(pp ! tt̄) =• What are μF/R

ab

XZ
ab

dx1 dx2 fa (x1 , µF )fb (x2 , µF ) ⇥ ˆ (ab ! tt̄)dx1 dx2 fa (x1 , µF )fb (x2 , µF ) ⇥ ˆ (ab ! tt̄; µF , µR , ↵S (µR ))• They are arbitrary scales needed to renormalise the strong coupling
and to reabsorb initial state IR-divergences in PDFs, chosen to be of
the order of the hard scattering scales (sum of masses, pT, …)• The all-order cross-section is independent of the choice of μF/• At NkLO, the dependence is of Nk+1LO

 

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Scale uncertainties

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Scale uncertainties• Look at the LO and NLO cross-section we have just compute• Values with different scales are computed on the y and theenvelope is taken

INFO:
Final results and run summary:
Process p p > t t~ [QCD]
Run at p-p collider (6500 + 6500 GeV)
Total cross-section:
6.871e+02 +- 5.9e+00 pb
Ren. and fac. scale uncertainty: +9.7% -11.7%
INFO: The results of this run and the TopDrawer file withthe plots have been saved in /Users/marcozaro/Physics/
MadGraph/2.2.3new/my_tt_nlo_qcd/Events/run_01
INFO:
Final results and run summary:
Process p p > t t~ [QCD]
Run at p-p collider (6500 + 6500 GeV)
Total cross-section:
4.622e+02 +- 2.2e+00 pb
Ren. and fac. scale uncertainty: +29.8% -22.3%
INFO: The results of this run and the TopDrawer file withthe plots have been saved in /Users/marcozaro/Physics/
MadGraph/2.2.3new/my_tt_nlo_qcd/Events/run_02_LO

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Scale uncertainties• Look at the LO and NLO cross-section we have just compute• Values with different scales are computed on the y and theenvelope is taken• Typically LO has larger scale uncertainties

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Scale uncertainties• Look at the LO and NLO cross-section we have just compute• Values with different scales are computed on the y and theenvelope is taken• Typically LO has larger scale uncertainties• To have scale uncertainties for distributions, one must ll one
histogram per scale choice, and then take the envelope

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Scale uncertainties• Look at the LO and NLO cross-section we have just compute• Values with different scales are computed on the y and theenvelope is taken• Typically LO has larger scale uncertainties• To have scale uncertainties for distributions, one must ll one
histogram per scale choice, and then take the envelope• The same is possible for PDF uncertainties

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Scale uncertainties•=

tt inv mtt inv mtt inv m,
1 scale variation

tt inv m,
1 scale variation
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#1 rel.unc.

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L
~30% unc.

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-0.4

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σ per bin [pb]NLO
~10% unc.

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Scale uncertainties
pT(tt)̄ histogram from NLO run
tt pt
tt pt,
1 scale variation

effectively L~30-40% unc.

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σ per bin [pb]

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tt ̄ production at NLO
Part 2: Event generatio• Generate an event sample at NLO and LO to be showered by
Pythia8 (needs to be speci ed in the run_card)• Shower and analyse it with the py8an_HwU_pp_ttx.o analysis(to be speci ed in the shower_card• The histogramming routine (HwU.o) must also be added to theanalysis les in the shower_card(Hint: you can shower an existing run with ./bin/shower run_xx)
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Solution
Part• Generate a NLO event sample to be showered by Pythia6• Shower it with the mcatnlo_pyan_pp_ttx analysis (to be speci ed in
the shower_card• cd my_ttbar_nl• ./bin/aMCatNL• > launc• > fixed_order=OF• > shower=O• Edit run_card• Edit shower_card

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SolutionPart# 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#***********************************************************************# 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#***********************************************************************# Renormalization and factorization scales*# (Default functional form for the non-fixed scales is the sum of*# the transverse masses of all final state particles and partons. This*# can be changed in SubProcesses/set_scales.f)*#***********************************************************************
F= fixed_ren_scale ! if .true. use fixed ren scaleF= fixed_fac_scale ! if .true. use fixed fac scale
91.188= muR_ref_fixed! fixed ren reference scale
91.188= muF1_ref_fixed! fixed fact reference scale for pdf1
91.188= muF2_ref_fixed! fixed fact reference scale for pdf2#***********************************************************************# Renormalization and factorization scales (advanced and NLO options)*#***********************************************************************• Generate a NLO event sample to be showered by Pythia6• Shower it with the mcatnlo_pyan_pp_ttx analysis (to be speci ed in
the shower_card• cd my_ttbar_nl• ./bin/aMCatNL• > launc• > fixed_order=OF• > shower=O• Edit run_card• Edit shower_card

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SolutionPart# 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#***********************************************************************# 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#***********************************************************************# Renormalization and factorization scales*#***********************************************************************# (Default
functional form for the non-fixed scales is the sum of# Extra Libraries/analyses
*
*
#
The
following
lines
need
to
be
changed
if
the
user
does
not
want
to
*
# the transverse masses of all final state particles and partons. This# create a StdHEP/HepMC file, but to directly run an own analysis (to **be changed
placed inor analogous MCatNLO subfolders).
*# can# bein HWAnalyzer
SubProcesses/set_scales.f)#
Please
use
files
in
those
foldersasexamples.
**#***********************************************************************#**********************************************************************EXTRALIBS=# Extra-libraries (not LHAPDF)*# Default:"stdhep
Fmcfio"F= fixed_ren_scale ! if .true.
use fixed
ren scale#PYTHIA>
8.200
may
require library dlF= fixed_fac_scale ! if .true. use fixed fac scale
EXTRAPATHS=../lib
#
Path
to
the
extra-libraries
91.188= muR_ref_fixed! fixed ren reference scale# Default:"../lib"
91.188= muF1_ref_fixed! fixed factreferencescale for pdf1
INCLUDEPATHS
=
#
Path
to
headerfiles
91.188= muF2_ref_fixed! fixed fact reference scale
forneeded
pdf2 by c++
#
Dir
names
separatedbywhite spaces#**********************************************************************ANALYSE=
py8an_HwU_pp_ttx.o
HwU.o*# routines(pleaseas extension# Renormalization and factorization scales(advanced
and useNLO .ooptions)#
anduse
spacestoseparatefiles)*#***********************************************************************• Generate a NLO event sample to be showered by Pythia6• Shower it with the mcatnlo_pyan_pp_ttx analysis (to be speci ed in
the shower_card• cd my_ttbar_nl• ./bin/aMCatNL• > launc• > fixed_order=OF• > shower=O• Edit run_card• Edit shower_card

fi

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SolutionPart# PDF choice: this automatically fixes also alpha_s(MZ) and its evol.
*#**********************************************************************
Summary:*
Process p p > t t~ [QCD]nn23nlo= pdlabel! PDF set
Run
at
p-p
collider(6500 + 6500 GeV)
244600= lhaid! if pdlabel=lhapdf, this is the lhapdf number
Total cross-section: 6.772e+02 +- 2.1e+00 pb#**********************************************************************
Ren. and fac. scale uncertainty: +11.5% -13.0%*
Numbergenerated:
100000# Include
the of
NLOevents
Monte Carlo
subtr. terms
for the following parton*
Parton shower to be used: PYTHIA6Q# shower(HERWIG6HERWIGPP |weights:
PYTHIA6Q |0.20
PYTHIA6PT | PYTHIA8)
Fractionof |negative*
Total running time : 6m 58s# WARNING: PYTHIA6PT works only for processes without FSR!!!!
*INFO:
The /Users/marcozaro/Physics/MadGraph/2.2.3new/my_tt_nlo_qcd/Events/#**********************************************************************
run_12/events.lhe.gz
file has been generated.
*
PYTHIA8=
parton_shower. . .
#**********************************************************************
INFO:
Preparing MCatNLO run*
INFO: Compiling MCatNLO for PYTHIA6Q...
# Renormalization and factorization scales
INFO:... done*
INFO:Showering
events...
#***********************************************************************# (Default
functional
form for the non-fixed scales is the sum of#Extra
Libraries/analyses*
INFO:(Running
in/Users/marcozaro/Physics/MadGraph/2.2.3new/my_tt_nlo_qcd/*#
Thefollowing
lines
need
to
be
changed
if
the
user
does
not
want
to
*
MCatNLO/RUN_PYTHIA6Q_3)# the transverse masses of all final state particles and partons. This
# Idle:create 0,a StdHEP/HepMC
but to directlyan own time:
analysis(to ]**INFO:
Running: file,1, Completed:
0 [ runcurrent
12h32#
beplacedin
HWAnalyzer
oranalogous
MCatNLOsubfolders).
*# can bechangedin
SubProcesses/set_scales.f)
INFO:
Idle:
0,
Running:
0, folders
Completed:1 [ 2m 35s ]#Please
use
files
in
those
as
examples.
**INFO:
Idle: 0, Running: 0, Completed: 0 [ current time: 12h34 ]#***********************************************************************#**********************************************************************INFO:
The file /Users/marcozaro/Physics/MadGraph/2.3.1/ttbar/Events/run_01/
EXTRALIBS=# Extra-libraries (not LHAPDF)*# Default:"stdhep
Fmcfio"plot_PYTHIA6Q_1_0.HwU
has
generated,within the HwU andF= fixed_ren_scale been
! if .true.
use fixed
renhistograms
scale#
PYTHIA>
8.200
may
requirelibrarydl
GnuPlot
formats,
obtained byshowering
parton-level
file /Users/
F= fixed_fac_scale! if.true. usethe
fixed
fac scale
EXTRAPATHS=../lib
#
Path
to
the
extra-libraries
91.188= muR_ref_fixed! fixed ren reference scale
marcozaro/Physics/MadGraph/2.3.1/ttbar/Events/run_01/events.lhe.gz
with# Default:"../lib"
91.188=
muF1_ref_fixed
!
fixed
fact
reference
scale
for
pdf1
PYTHIA6Q.
INCLUDEPATHS=# Pathto headerfiles
91.188= muF2_ref_fixed! fixed factreference
scale
forneeded
pdf2 by c++
INFO:
Run complete
#
Dir
names
separatedbywhite spaces#**********************************************************************ANALYSE=
py8an_HwU_pp_ttx.o
HwU.o*# routines(pleaseas extension# Renormalization and factorization scales(advanced
and useNLO .ooptions)#
anduse
spacestoseparatefiles)*#***********************************************************************• Generate a NLO event sample to be showered by Pythia6• Shower it with the mcatnlo_pyan_pp_ttx analysis (to be speci ed in
the shower_card• cd my_ttbar_nl• ./bin/aMCatNL• > launc• > fixed_order=OF• > shower=O• Edit run_card• Edit shower_card

fi

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Solution
tt pt

Part

tt pt, NOCUT# PDF choice: this automatically fixes also alpha_s(MZ)
and its evol.
NOCUT scale variation*
CUT
CUT scale variation#**********************************************************************
Summary:*
Process p p > t t~ [QCD]nn23nlo= pdlabel! PDF set
2
Run
at
p-p
collider(6500 + 6500 GeV)
10244600= lhaid! if pdlabel=lhapdf, this is the lhapdf number
Total cross-section: 6.772e+02 +- 2.1e+00 pb#**********************************************************************
Ren. and fac. scale uncertainty: +11.5% -13.0%*
Numbergenerated:
100000# Include
the of
NLOevents
Monte Carlo
subtr. terms
for the following parton*
Parton shower to be used: PYTHIA6Q# shower(HERWIG6HERWIGPP |weights:
PYTHIA6Q |0.20
PYTHIA6PT | PYTHIA8)
Fractionof |negative*
Total running time : 6m 58s# WARNING: PYTHIA6PT works only for processes without FSR!!!!
*INFO:
The /Users/marcozaro/Physics/MadGraph/2.2.3new/my_tt_nlo_qcd/Events/
101#**********************************************************************
run_12/events.lhe.gz
file has been generated.
*
PYTHIA8=
parton_shower. . .
#**********************************************************************
INFO:
Preparing MCatNLO run*
INFO: Compiling MCatNLO for PYTHIA6Q...
# Renormalization and factorization scales
INFO:... done*
INFO:Showering
events...
#***********************************************************************# (Default
functional
form for the non-fixed scales is the sum of#Extra
Libraries/analyses*
INFO:(Running
in/Users/marcozaro/Physics/MadGraph/2.2.3new/my_tt_nlo_qcd/
0.3
*
#
The
following
lines
need
to
be
changed
if
the
user
does
not
want
to
*
MCatNLO/RUN_PYTHIA6Q_3)# the transverse masses of all final state particles and partons. This
0.2
# Idle:create 0,a StdHEP/HepMC
but to directlyan own time:
analysis(to ]**INFO:
Running: file,1, Completed:
0 [ runcurrent
12h32
0.1
#
be
placedin
HWAnalyzer
oranalogous
MCatNLOsubfolders).
*# can bechangedin
SubProcesses/set_scales.f)
INFO:
Idle:
0,
Running:
0, folders
Completed:1 [ 2m 35s ]0#Please
use
files
in
those
as
examples.
**INFO:
Idle: 0, Running: 0, Completed: 0 [ current time: 12h34 ]#***********************************************************************-0.1#**********************************************************************INFO:
The file /Users/marcozaro/Physics/MadGraph/2.3.1/ttbar/Events/run_01/
EXTRALIBS=# Extra-libraries (not LHAPDF)-0.2*
Relative uncertainties# Default:"stdhep
Fmcfio"plot_PYTHIA6Q_1_0.HwU
has
generated,within the HwU andF= fixed_ren_scale been
! if .true.
use fixed
renhistograms
scale
-0.3
#
PYTHIA>
8.200
may
requirelibrarydl
GnuPlot
formats,
obtained byshowering
parton-level
file /Users/
F= fixed_fac_scale! if.true. usethe
fixed
fac scale
0.95
EXTRAPATHS=../lib
#
Path
to
the
extra-libraries
91.188= muR_ref_fixed! fixed ren reference scale
marcozaro/Physics/MadGraph/2.3.1/ttbar/Events/run_01/events.lhe.gz
with# Default:"../lib"
0.9
91.188=
muF1_ref_fixed
!
fixed
fact
reference
scale
for
pdf1
PYTHIA6Q.
INCLUDEPATHS=# Pathto headerfiles
91.188= muF2_ref_fixed! fixed factreference
scale
forneeded
pdf2 by c++
0.85
INFO:
Run complete
#
Dir
names
separatedbywhite spaces#**********************************************************************
0.8
ANALYSE=
py8an_HwU_pp_ttx.o
HwU.o*# routines(pleaseas extension
0.75# Renormalization and factorization scales(advanced
and useNLO .ooptions)(2)/NOCUT#
anduse
spacestoseparatefiles)*
0.7#**********************************************************************
0
20
40
60
80
100
*

• Generate a NLO event sample to be showered by Pythia6• Shower it with the mcatnlo_pyan_pp_ttx analysis (to be speci ed inσ per bin [pb]the shower_card

MadGraph5_aMC@NLO• cd my_ttbar_nl• ./bin/aMCatNL• > launc• > fixed_order=OF• > shower=O(2)/NOCUTNOCUT rel.unc.

• Edit run_card• Edit shower_card

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The events<initrwgt><weightgroup type='scale_variation' combine='envelope'><weight id='1001'> muR=0.10000E+01 muF=0.10000E+01 </weight><weight id='1002'> muR=0.10000E+01 muF=0.20000E+01 </weight><weight id='1003'> muR=0.10000E+01 muF=0.50000E+00 </weight><weight id='1004'> muR=0.20000E+01 muF=0.10000E+01 </weight><weight id='1005'> muR=0.20000E+01 muF=0.20000E+01 </weight><weight id='1006'> muR=0.20000E+01 muF=0.50000E+00 </weight><weight id='1007'> muR=0.50000E+00 muF=0.10000E+01 </weight><weight id='1008'> muR=0.50000E+00 muF=0.20000E+01 </weight><weight id='1009'> muR=0.50000E+00 muF=0.50000E+00 </weight></weightgroup></initrwgt></header><init>
2212
2212 0.65000000E+04 0.65000000E+04 -1 -1 244600 244600 -4
10.68147533E+03 0.22760274E+01 0.11811897E+04
0</init><event>4
0 -.11811897E+04 0.68991465E+03 0.75467716E-02 0.11800000E+00
21 -1
00 501 502 0.00000000E+00 0.00000000E+00 0.16695776E+03 0.16695776E+03 0.00000000E+00 0.0000E+00
0.9000E+01
21 -1
00 502 503 -.00000000E+00 -.00000000E+00 -.83539498E+03 0.83539498E+03 0.00000000E+00 0.0000E+00
0.9000E+01
6 1
1
2 501
0 -.87405313E+02 -.30435858E+03 -.46344397E+03 0.58735266E+03 0.17300000E+03 0.0000E+00
0.9000E+01-6 1
12
0 503 0.87405313E+02 0.30435858E+03 -.20499324E+03 0.41500008E+03 0.17300000E+03 0.0000E+00
0.9000E+01#aMCatNLO 1 5 3 3 2 0.21343976E+03 0.35860250E+02 9 0 0 0.10000001E+01 0.15353083E+01 0.66887201E+00 0.00E+00 0.0E+00<rwgt><wgt id='1001'> -.11812E+04 </wgt><wgt id='1002'> -.10571E+04 </wgt><wgt id='1003'> -.13263E+04 </wgt><wgt id='1004'> -.88285E+03 </wgt><wgt id='1005'> -.79006E+03 </wgt>. . .

• Each event keeps information aboutscale variation• To obtain scale uncertainties use theextra weights to ll histograms andtake the envelope

15
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Marco Zaro, 21-06-2022

NLO exercise
tt ̄ production at NLO
Part 3: Decay and spin correlation• Generate a NLO event sample to be showered by Pythia• Shower and analyse it with the py8an_HwU_pp_ttx.o analysis (to be
speci ed in the shower_card• The histogramming routine (HwU.o) must also be added to the analysis les inthe shower_card (Hint: you can shower an existing run with ./bin/shower run_xx• Use MadSpin to generate a di-leptonic (into muons) decayed sampl• Re-analyse the decayed and undecided sample with thepy6an_HwU_pp_lplm.o analysis and check the lepton pair pT• The analysis (in MCatNLO/PYAnalyzer/py6an_HwU_pp_lplm.f)has to beslightly modi ed:• IORI.LE.10 → IORI.LE.20 at lines 186, 190• To tell Pythia to perform di-leptonic decays, add these lines in theshower_card (‘Decay channels’ block; antiparticles are decayed as particles• DM_1 = 6 > 24 5 @1d0 @100

DM_2 = 24 > 14 -13 @1d0 @100

)

fi

e

)

8

s

)

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Marco Zaro, ICS 2024

NLO exercise
SolutionPart• Generate a NLO event sample to be showered by Pythia6• Shower it with the mcatnlo_pyan_pp_ttx analysis (to be speci ed in
the shower_card• cd my_ttbar_nl• ./bin/aMCatNL• > launc• > fixed_order=OF• > shower=O• Edit run_card• Edit shower_card

fi

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Marco Zaro, ICS 2024

NLO exercise
SolutionPart# 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#***********************************************************************# 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#***********************************************************************# Renormalization and factorization scales*# (Default functional form for the non-fixed scales is the sum of*# the transverse masses of all final state particles and partons. This*# can be changed in SubProcesses/set_scales.f)*#***********************************************************************
F= fixed_ren_scale ! if .true. use fixed ren scaleF= fixed_fac_scale ! if .true. use fixed fac scale
91.188= muR_ref_fixed! fixed ren reference scale
91.188= muF1_ref_fixed! fixed fact reference scale for pdf1
91.188= muF2_ref_fixed! fixed fact reference scale for pdf2#***********************************************************************# Renormalization and factorization scales (advanced and NLO options)*#***********************************************************************• Generate a NLO event sample to be showered by Pythia6• Shower it with the mcatnlo_pyan_pp_ttx analysis (to be speci ed in
the shower_card• cd my_ttbar_nl• ./bin/aMCatNL• > launc• > fixed_order=OF• > shower=O• Edit run_card• Edit shower_card

fi

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NLO exercise
SolutionPart# 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#***********************************************************************# 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#***********************************************************************# Renormalization and factorization scales*#***********************************************************************# (Default
functional form for the non-fixed scales is the sum of# Extra Libraries/analyses
*
*
#
The
following
lines
need
to
be
changed
if
the
user
does
not
want
to
*
# the transverse masses of all final state particles and partons. This# create a StdHEP/HepMC file, but to directly run an own analysis (to **be changed
placed inor analogous MCatNLO subfolders).
*# can# bein HWAnalyzer
SubProcesses/set_scales.f)#
Please
use
files
in
those
foldersasexamples.
**#***********************************************************************#**********************************************************************EXTRALIBS=# Extra-libraries (not LHAPDF)*# Default:"stdhep
Fmcfio"F= fixed_ren_scale ! if .true.
use fixed
ren scale#PYTHIA>
8.200
may
require library dlF= fixed_fac_scale ! if .true. use fixed fac scale
EXTRAPATHS=../lib
#
Path
to
the
extra-libraries
91.188= muR_ref_fixed! fixed ren reference scale# Default:"../lib"
91.188= muF1_ref_fixed! fixed factreferencescale for pdf1
INCLUDEPATHS
=
#
Path
to
headerfiles
91.188= muF2_ref_fixed! fixed fact reference scale
forneeded
pdf2 by c++
#
Dir
names
separatedbywhite spaces#**********************************************************************ANALYSE=
py8an_HwU_pp_ttx.o
HwU.o*# routines(pleaseas extension# Renormalization and factorization scales(advanced
and useNLO .ooptions)#
anduse
spacestoseparatefiles)*#***********************************************************************• Generate a NLO event sample to be showered by Pythia6• Shower it with the mcatnlo_pyan_pp_ttx analysis (to be speci ed in
the shower_card• cd my_ttbar_nl• ./bin/aMCatNL• > launc• > fixed_order=OF• > shower=O• Edit run_card• Edit shower_card

fi

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Marco Zaro, ICS 2024

NLO exercise
SolutionPart# PDF choice: this automatically fixes also alpha_s(MZ) and its evol.
*#**********************************************************************
Summary:*
Process p p > t t~ [QCD]nn23nlo= pdlabel! PDF set
Run
at
p-p
collider(6500 + 6500 GeV)
244600= lhaid! if pdlabel=lhapdf, this is the lhapdf number
Total cross-section: 6.772e+02 +- 2.1e+00 pb#**********************************************************************
Ren. and fac. scale uncertainty: +11.5% -13.0%*
Numbergenerated:
100000# Include
the of
NLOevents
Monte Carlo
subtr. terms
for the following parton*
Parton shower to be used: PYTHIA6Q# shower(HERWIG6HERWIGPP |weights:
PYTHIA6Q |0.20
PYTHIA6PT | PYTHIA8)
Fractionof |negative*
Total running time : 6m 58s# WARNING: PYTHIA6PT works only for processes without FSR!!!!
*INFO:
The /Users/marcozaro/Physics/MadGraph/2.2.3new/my_tt_nlo_qcd/Events/#**********************************************************************
run_12/events.lhe.gz
file has been generated.
*
PYTHIA8=
parton_shower. . .
#**********************************************************************
INFO:
Preparing MCatNLO run*
INFO: Compiling MCatNLO for PYTHIA6Q...
# Renormalization and factorization scales
INFO:... done*
INFO:Showering
events...
#***********************************************************************# (Default
functional
form for the non-fixed scales is the sum of#Extra
Libraries/analyses*
INFO:(Running
in/Users/marcozaro/Physics/MadGraph/2.2.3new/my_tt_nlo_qcd/*#
Thefollowing
lines
need
to
be
changed
if
the
user
does
not
want
to
*
MCatNLO/RUN_PYTHIA6Q_3)# the transverse masses of all final state particles and partons. This
# Idle:create 0,a StdHEP/HepMC
but to directlyan own time:
analysis(to ]**INFO:
Running: file,1, Completed:
0 [ runcurrent
12h32#
beplacedin
HWAnalyzer
oranalogous
MCatNLOsubfolders).
*# can bechangedin
SubProcesses/set_scales.f)
INFO:
Idle:
0,
Running:
0, folders
Completed:1 [ 2m 35s ]#Please
use
files
in
those
as
examples.
**INFO:
Idle: 0, Running: 0, Completed: 0 [ current time: 12h34 ]#***********************************************************************#**********************************************************************INFO:
The file /Users/marcozaro/Physics/MadGraph/2.3.1/ttbar/Events/run_01/
EXTRALIBS=# Extra-libraries (not LHAPDF)*# Default:"stdhep
Fmcfio"plot_PYTHIA6Q_1_0.HwU
has
generated,within the HwU andF= fixed_ren_scale been
! if .true.
use fixed
renhistograms
scale#
PYTHIA>
8.200
may
requirelibrarydl
GnuPlot
formats,
obtained byshowering
parton-level
file /Users/
F= fixed_fac_scale! if.true. usethe
fixed
fac scale
EXTRAPATHS=../lib
#
Path
to
the
extra-libraries
91.188= muR_ref_fixed! fixed ren reference scale
marcozaro/Physics/MadGraph/2.3.1/ttbar/Events/run_01/events.lhe.gz
with# Default:"../lib"
91.188=
muF1_ref_fixed
!
fixed
fact
reference
scale
for
pdf1
PYTHIA6Q.
INCLUDEPATHS=# Pathto headerfiles
91.188= muF2_ref_fixed! fixed factreference
scale
forneeded
pdf2 by c++
INFO:
Run complete
#
Dir
names
separatedbywhite spaces#**********************************************************************ANALYSE=
py8an_HwU_pp_ttx.o
HwU.o*# routines(pleaseas extension# Renormalization and factorization scales(advanced
and useNLO .ooptions)#
anduse
spacestoseparatefiles)*#***********************************************************************• Generate a NLO event sample to be showered by Pythia6• Shower it with the mcatnlo_pyan_pp_ttx analysis (to be speci ed in
the shower_card• cd my_ttbar_nl• ./bin/aMCatNL• > launc• > fixed_order=OF• > shower=O• Edit run_card• Edit shower_card

fi

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Marco Zaro, ICS 2024

NLO exercise
Solution
tt pt

Part

tt pt, NOCUT# PDF choice: this automatically fixes also alpha_s(MZ)
and its evol.
NOCUT scale variation*
CUT
CUT scale variation#**********************************************************************
Summary:*
Process p p > t t~ [QCD]nn23nlo= pdlabel! PDF set
2
Run
at
p-p
collider(6500 + 6500 GeV)
10244600= lhaid! if pdlabel=lhapdf, this is the lhapdf number
Total cross-section: 6.772e+02 +- 2.1e+00 pb#**********************************************************************
Ren. and fac. scale uncertainty: +11.5% -13.0%*
Numbergenerated:
100000# Include
the of
NLOevents
Monte Carlo
subtr. terms
for the following parton*
Parton shower to be used: PYTHIA6Q# shower(HERWIG6HERWIGPP |weights:
PYTHIA6Q |0.20
PYTHIA6PT | PYTHIA8)
Fractionof |negative*
Total running time : 6m 58s# WARNING: PYTHIA6PT works only for processes without FSR!!!!
*INFO:
The /Users/marcozaro/Physics/MadGraph/2.2.3new/my_tt_nlo_qcd/Events/
101#**********************************************************************
run_12/events.lhe.gz
file has been generated.
*
PYTHIA8=
parton_shower. . .
#**********************************************************************
INFO:
Preparing MCatNLO run*
INFO: Compiling MCatNLO for PYTHIA6Q...
# Renormalization and factorization scales
INFO:... done*
INFO:Showering
events...
#***********************************************************************# (Default
functional
form for the non-fixed scales is the sum of#Extra
Libraries/analyses*
INFO:(Running
in/Users/marcozaro/Physics/MadGraph/2.2.3new/my_tt_nlo_qcd/
0.3
*
#
The
following
lines
need
to
be
changed
if
the
user
does
not
want
to
*
MCatNLO/RUN_PYTHIA6Q_3)# the transverse masses of all final state particles and partons. This
0.2
# Idle:create 0,a StdHEP/HepMC
but to directlyan own time:
analysis(to ]**INFO:
Running: file,1, Completed:
0 [ runcurrent
12h32
0.1
#
be
placedin
HWAnalyzer
oranalogous
MCatNLOsubfolders).
*# can bechangedin
SubProcesses/set_scales.f)
INFO:
Idle:
0,
Running:
0, folders
Completed:1 [ 2m 35s ]0#Please
use
files
in
those
as
examples.
**INFO:
Idle: 0, Running: 0, Completed: 0 [ current time: 12h34 ]#***********************************************************************-0.1#**********************************************************************INFO:
The file /Users/marcozaro/Physics/MadGraph/2.3.1/ttbar/Events/run_01/
EXTRALIBS=# Extra-libraries (not LHAPDF)-0.2*
Relative uncertainties# Default:"stdhep
Fmcfio"plot_PYTHIA6Q_1_0.HwU
has
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! if .true.
use fixed
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#
PYTHIA>
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GnuPlot
formats,
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F= fixed_fac_scale! if.true. usethe
fixed
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0.95
EXTRAPATHS=../lib
#
Path
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the
extra-libraries
91.188= muR_ref_fixed! fixed ren reference scale
marcozaro/Physics/MadGraph/2.3.1/ttbar/Events/run_01/events.lhe.gz
with# Default:"../lib"
0.9
91.188=
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INCLUDEPATHS=# Pathto headerfiles
91.188= muF2_ref_fixed! fixed factreference
scale
forneeded
pdf2 by c++
0.85
INFO:
Run complete
#
Dir
names
separatedbywhite spaces#**********************************************************************
0.8
ANALYSE=
py8an_HwU_pp_ttx.o
HwU.o*# routines(pleaseas extension
0.75# Renormalization and factorization scales(advanced
and useNLO .ooptions)(2)/NOCUT#
anduse
spacestoseparatefiles)*
0.7#**********************************************************************
0
20
40
60
80
100
*

• Generate a NLO event sample to be showered by Pythia6• Shower it with the mcatnlo_pyan_pp_ttx analysis (to be speci ed inσ per bin [pb]the shower_card

MadGraph5_aMC@NLO• cd my_ttbar_nl• ./bin/aMCatNL• > launc• > fixed_order=OF• > shower=O(2)/NOCUTNOCUT rel.unc.

• Edit run_card• Edit shower_card

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The events<initrwgt><weightgroup type='scale_variation' combine='envelope'><weight id='1001'> muR=0.10000E+01 muF=0.10000E+01 </weight><weight id='1002'> muR=0.10000E+01 muF=0.20000E+01 </weight><weight id='1003'> muR=0.10000E+01 muF=0.50000E+00 </weight><weight id='1004'> muR=0.20000E+01 muF=0.10000E+01 </weight><weight id='1005'> muR=0.20000E+01 muF=0.20000E+01 </weight><weight id='1006'> muR=0.20000E+01 muF=0.50000E+00 </weight><weight id='1007'> muR=0.50000E+00 muF=0.10000E+01 </weight><weight id='1008'> muR=0.50000E+00 muF=0.20000E+01 </weight><weight id='1009'> muR=0.50000E+00 muF=0.50000E+00 </weight></weightgroup></initrwgt></header><init>
2212
2212 0.65000000E+04 0.65000000E+04 -1 -1 244600 244600 -4
10.68147533E+03 0.22760274E+01 0.11811897E+04
0</init><event>4
0 -.11811897E+04 0.68991465E+03 0.75467716E-02 0.11800000E+00
21 -1
00 501 502 0.00000000E+00 0.00000000E+00 0.16695776E+03 0.16695776E+03 0.00000000E+00 0.0000E+00
0.9000E+01
21 -1
00 502 503 -.00000000E+00 -.00000000E+00 -.83539498E+03 0.83539498E+03 0.00000000E+00 0.0000E+00
0.9000E+01
6 1
1
2 501
0 -.87405313E+02 -.30435858E+03 -.46344397E+03 0.58735266E+03 0.17300000E+03 0.0000E+00
0.9000E+01-6 1
12
0 503 0.87405313E+02 0.30435858E+03 -.20499324E+03 0.41500008E+03 0.17300000E+03 0.0000E+00
0.9000E+01#aMCatNLO 1 5 3 3 2 0.21343976E+03 0.35860250E+02 9 0 0 0.10000001E+01 0.15353083E+01 0.66887201E+00 0.00E+00 0.0E+00<rwgt><wgt id='1001'> -.11812E+04 </wgt><wgt id='1002'> -.10571E+04 </wgt><wgt id='1003'> -.13263E+04 </wgt><wgt id='1004'> -.88285E+03 </wgt><wgt id='1005'> -.79006E+03 </wgt>. . .

• Each event keeps information aboutscale variation• To obtain scale uncertainties use theextra weights to ll histograms andtake the envelope

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NLO exercise
SolutionPart• Use MadSpin to generate a di-leptonic (into muons) decayed sampl• ./bin/aMCatNL• > decay_events run_x• edit the madspin_card

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NLO exercise
SolutionPart• Use MadSpin to generate a di-leptonic (into muons) decayed sampl• ./bin/aMCatNL• > decay_events run_x• edit the madspin_card#************************************************************#*
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*#**#************************************************************#Some options (uncomment to apply)## set seed 1# set Nevents_for_max_weigth 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 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+ > mu+ vm
decay t~ > w- b~, w- > mu- vm~# running the actual code
launch
~

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NLO exercise
SolutionPart• Use MadSpin to generate a di-leptonic (into muons) decayed sampl. . .
INFO: MadSpin: Estimate the maximum weight
INFO:
INFO:
Estimating the maximum weight
INFO:*****************************
INFO:
Probing the first 139 events
INFO:
with 400 phase space points
INFO:
INFO: Event 1/139 : 0.059s
INFO: Event 6/139 : 0.99s#************************************************************
INFO: Event 11/139 : 1.3s#*
MadSpin . . .
*
2
2
2
#*
*2
INFO: Decaying the events...
P +D
P *
P+D
P
#*
P. Artoisenet, R. Frederix, R. Rietkerk,
INFO: EventO.nbMattelaer
1000 2.6s#**
Event nb 2000 4.9s#*
Part of the MadGraph5_aMC@NLOINFO:
Framework:
*
INFO:
Event
nb
3000
7s
#*
The MadGraph5_aMC@NLO Development Team - Find us at
*
. . .
#*
https://server06.fynu.ucl.ac.be/projects/madgraph*#**
INFO: Decayed events havebeen written in /Users/marcozaro/Physics/#************************************************************MadGraph/2.2.3new/my_tt_nlo_qcd/Events/run_01/events_decayed.lhe.gz#Some options (uncomment to apply) INFO: The decayed event file has been moved to the following location:#
INFO: /Users/marcozaro/Physics/MadGraph/2.2.3new/my_tt_nlo_qcd/Events/# set seed 1
run_01_decayed_1/events.lhe.gz# set Nevents_for_max_weigth 75 # numberof events for the estimate of the max. weight
INFO:
MadSpin# set BW_cut 15# cut on how
far theDone
particle can be off-shell• ./bin/aMCatNL• > decay_events run_x• edit the madspin_card|MMS⇣ estimate| / |M | > Rand() max |M| / |M |with the rst events

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+ > mu+ vm
decay t~ > w- b~, w- > mu- vm~# running the actual code
launch
~

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NLO exercise
SolutionPart• Re-analyse the decayed and undecided sample with thepy6an_HwU_pp_lplm analysis and check the the lepton pair p• Re-shower the un-decayed sampl• ./bin/shower run_x• edit the shower_card• Shower the decayed sampl• ./bin/shower run_xx_decayed_1

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NLO exercise
SolutionPart• Re-analyse the decayed and undecided sample with thepy6an_HwU_pp_lplm analysis and check the the lepton pair p• Re-shower the un-decayed sampl• ./bin/shower run_x• edit the shower_card• Shower the decayed sampl# Decay channels*# Write down the decay channels for the resonances, to be performed by *# the shower.
*. . .
DM_1 = 6 > 24 5 @1d0 @100
DM_2 = -6 > -24 -5 @1d0 @100
DM_3 = 24 > 14 -13 @1d0 @100
DM_4 = —24 > -14 13 @1d0 @100#***********************************************************************#***********************************************************************# Extra Libraries/analyses*# The following lines need to be changed if the user does not want to *# create a StdHEP/HepMC file, but to directly run an own analysis (to *# be placed in HWAnalyzer or analogous MCatNLO subfolders).
*# Please use files in those folders as examples.
*#***********************************************************************EXTRALIBS=# Extra-libraries (not LHAPDF)# Default: "stdhep Fmcfio"# PYTHIA > 8.200 may require library dl
EXTRAPATHS= ../lib# Path to the extra-libraries# Default: "../lib"
INCLUDEPATHS =# Path to header files needed by c++# Dir names separated by white spaces
ANALYSE= mcatnlo_pyan_pp_lplm.o mcatnlo_hbook_gfortran8.o# routines (please use .o as extension# and use spaces to separate files)• ./bin/shower run_xx_decayed_1

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NLO exercise
SolutionPart• Re-analyse the decayed and undecided sample with thepy6an_HwU_pp_lplm analysis and check the the lepton pair p• Re-shower the un-decayed sampl• ./bin/shower run_x

INFO: Preparing MCatNLO run
INFO: Compiling MCatNLO for PYTHIA6Q...
# Decay channels*
Write down the decay channels for the resonances, to be performed by *INFO:...# done# the shower.
*
INFO: Showering events...
.
.
.
INFO: (Running in /Users/marcozaro/Physics/MadGraph/2.2.3new/my_tt_nlo_qcd/
DM_1 = 6 > 24 5 @1d0 @100
MCatNLO/RUN_PYTHIA6Q_3)
DM_2 = -6 > -24 -5 @1d0 @100
INFO: Idle: 0, Running: 1, DM_3
Completed:[ current= 24 > 140-13@1d0 @100time: 12h32 ]INFO: Idle: 0, Running: 0, DM_4
Completed:1[= —24 > -14 13 2m@1d035s@100 ]
INFO: Idle: 0, Running: 0, #***********************************************************************
Completed: 0 [ current time: 12h34 ]#***********************************************************************
INFO: The file /Users/marcozaro/Physics/MadGraph/2.3.1/ttbar/Events/run_01/
Extra Libraries/analyses*
plot_PYTHIA6Q_2_0.HwU has been# generated,with histograms in the HwU and#The
following
lines
need
to
be
changed
if
the
user
does
not
want
to
*
GnuPlot formats, obtained by showering the parton-level file /Users/# create a StdHEP/HepMC file, but to directly run an own analysis (to *marcozaro/Physics/MadGraph/2.3.1/ttbar/Events/run_01/events.lhe.gz
with# be placed in HWAnalyzer or analogous MCatNLO subfolders).
*
PYTHIA6Q.
# Please use files in those folders as examples.
*
INFO: Run complete#***********************************************************************EXTRALIBS=# Extra-libraries (not LHAPDF). . .
INFO: Idle: 0, Running: 1, Completed: 0 [ current time:# Default:
12h32 ] "stdhep Fmcfio"#
PYTHIA> 8.200 may require library dl
INFO: Idle: 0, Running: 0, Completed: 1 [ 2m 35s ]EXTRAPATHS= ../lib# Path to the extra-libraries
INFO: Idle: 0, Running: 0, Completed: 0 [ current time: 12h34 ]# Default: "../lib"
INFO: INFO: The file /Users/marcozaro/Physics/MadGraph/2.3.1/ttbar/Events/
INCLUDEPATHS =# Path to header files needed by c++
run_01_decayed_1/plot_PYTHIA6Q_1_0.HwU has been generated,# Dir
withnames
histograms
separatedinby white spaces
the HwU and GnuPlot formats, obtained
by =showering
the parton-level
file /ANALYSEmcatnlo_pyan_pp_lplm.omcatnlo_hbook_gfortran8.o# routines (please use .o as extension
Users/marcozaro/Physics/MadGraph/2.3.1/ttbar/Events/run_01_decayed_1/# and use spaces to separate files)
events.lhe.gz with PYTHIA6Q.
INFO: Run complete• edit the shower_card• Shower the decayed sampl• ./bin/shower run_xx_decayed_1

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√S = 14 TeV) and at the Tevatron run II
the predictions given in this section have b
default PDF set [9], and by setting mt = 1
of single-t production, we also reconstruct t
kT -clustering algorithm [10], with dcut = 1
Part
procedure all final-state stable hadrons andsamplewith the• Re-analyse the decayed and undecided
0
force π ’s and all lowest-lying b-flavoured st
mcatnlo_pyan_pp_lplm analysis and check the the lepton pair pT
are ordered in transverse momentum.

NLO exercise
Solution+-pT(l l )Plot from Frixione, Leanen, Motylinski, Webber, arXiv:hep-ph/0702198

100

σ per bin [pb]10-1

lp pt, MS

MadGraph5_aMC@NLO

lp pt, PY

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1/σ dσ/dpT(l+) [1/GeV]

Spin correlations in ttH
NLO Spin correlations on
LO Spin correlations on
NLO Spin correlations off
LO Spin correlations off

0.01

NLO Spin correlations on
LO Spin correlations on
NLO Spin correlations off
LO Spin correlations off

0.6

0.01
0.0001NLO Spin correlations on
Scalar Higgs LO Spin correlations on
NLO Spin correlations off
LO Spin correlations off

0

25

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75

0.5
NLO Spin correlations on
LO Spin correlations on
NLO Spin correlations off
LO Spin correlations off

0.6
0.45

100 125 150 175 200

1/σ dσ/dcos(φ)

1/σ dσ/dpT(l+) [1/GeV]

0.001
Higgs boson!

+pT(l ) [GeV]
0.001

Scalar Higgs

0.55
0.4

-1

-0.5

0
cos(φ)

0.5

1

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Figure 5: Next-to-leading-order cross sections differential in pT (l+ ) (left pane) and in cos φ (right
Higgs
0.45
pane) for tt̄H Scalar
eventswith or without spin correlation effects.
For comparison, also Scalar
the leadingHiggs
order results are shown. Events were generated with aMC@NLO, then decayed with MadSpin,
0.0001
0
25 to50Herwig
75 100for125
150 and
175 hadronization.
200
0.4
and finally passed
shower-1+pT(l ) [GeV]-0.5

0cos(φ)

0.5

1

1/σ dσ/dpT(l+) [1/GeV]NLO Spin correlations on
NLO Spin correlations on
+
0.6
NLO
Spin
correlations
off
NLO
Spin correlations
off φ (right
Figure 5: Next-to-leading-order cross sections differential in pT (l ) (left pane)
and in cos
1/σ dσ/dcos(φ)

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NLO Spin correlations on
Pseudoscalar
NLOHiggs
Spin correlations off
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0.0001Marco Zaro, ICS 2024

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75 100 125 150 175 200
pT(l+) [GeV]

0.5
NLO Spin correlations on
NLO Spin correlations off
Pseudoscalar Higgs

0.6
0.45

22

σ/dcos(φ)

pT(l+) [1/GeV]pane) for0.01tt̄H events with or without spin correlation effects. For comparison, also the leading0.55
order results are shown. Events were generated with aMC@NLO,
then decayed with MadSpin,and finally passed to Herwig for shower and hadronization.

0.55
0.4

-1

-0.5

0
cos(φ)

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Artoisenet, Frederix, Mattelaer, Rietkerk, arXiv:1212.3460

1/σ dσ/dcos(φ)• In ttH, spin correlations are crucial to distinguish a scalar vs pseudo scalar
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