The Event Generator WHIZARD for LC Top Physics - DESYreuter/downloads/LCTop2015.pdf · The Event...
Transcript of The Event Generator WHIZARD for LC Top Physics - DESYreuter/downloads/LCTop2015.pdf · The Event...
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J.R.Reuter WHIZARD for LC Top Physics LC Top 2015, IFIC Valencia, 1.7.2015
Jürgen R. Reuter, DESY
The Event Generator WHIZARD for LC Top Physics
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J.R.Reuter WHIZARD for LC Top Physics LC Top 2015, IFIC Valencia, 1.7.2015
1) Introduction into WHIZARD
2) Fixed-order NLO automation & POWHEG matching in WHIZARD
3) Top threshold in (N)LL (p)NRQCD matched to fixed order (N)LO in WHIZARD
Outline of the talk
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J.R.Reuter WHIZARD for LC Top Physics LC Top 2015, IFIC Valencia, 1.7.2015
1) Introduction to WHIZARD
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J.R.Reuter WHIZARD for LC Top Physics LC Top 2015, IFIC Valencia, 1.7.2015
WHIZARD: Some (technical) facts
WHIZARD Team: Wolfgang Kilian, Thorsten Ohl, JRRBijan Chokoufé/Marco Sekulla/Christian Weiss/Florian Staub + 2 Master + 2 PhD (soon)
(some losses: C. Speckner [software engineering], F. Bach [ESA Space Defense], S. Schmidt [Philosophy])
Publication: EPJ C71 (2011) 1742 (and others for O’Mega, Interfaces, color flow formalism)
WHIZARD v2.2.6 (02.05.2015) http://whizard.hepforge.org
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J.R.Reuter WHIZARD for LC Top Physics LC Top 2015, IFIC Valencia, 1.7.2015
WHIZARD: Some (technical) facts
WHIZARD Team: Wolfgang Kilian, Thorsten Ohl, JRRBijan Chokoufé/Marco Sekulla/Christian Weiss/Florian Staub + 2 Master + 2 PhD (soon)
(some losses: C. Speckner [software engineering], F. Bach [ESA Space Defense], S. Schmidt [Philosophy])
2nd WHIZARD Workshop Würzburg, 03/2015
Publication: EPJ C71 (2011) 1742 (and others for O’Mega, Interfaces, color flow formalism)
WHIZARD v2.2.6 (02.05.2015) http://whizard.hepforge.org
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J.R.Reuter WHIZARD for LC Top Physics LC Top 2015, IFIC Valencia, 1.7.2015
WHIZARD: Some (technical) facts
WHIZARD Team: Wolfgang Kilian, Thorsten Ohl, JRRBijan Chokoufé/Marco Sekulla/Christian Weiss/Florian Staub + 2 Master + 2 PhD (soon)
(some losses: C. Speckner [software engineering], F. Bach [ESA Space Defense], S. Schmidt [Philosophy])
2nd WHIZARD Workshop Würzburg, 03/2015
Publication: EPJ C71 (2011) 1742 (and others for O’Mega, Interfaces, color flow formalism)
support junior developers
WHIZARD v2.2.6 (02.05.2015) http://whizard.hepforge.org
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J.R.Reuter WHIZARD for LC Top Physics LC Top 2015, IFIC Valencia, 1.7.2015
WHIZARD: Introduction
WHIZARD Team: Wolfgang Kilian, Thorsten Ohl, JRR, Bijan Chokoufé/Marco Sekulla/Christian Weiss/Florian Staub + 2 Master + 2 PhD (soon) EPJ C71 (2011) 1742
WHIZARD v2.2.6 (02.05.2015) http://whizard.hepforge.org
• Universal event generator for lepton and hadron colliders
• Modular package: - Phase space parameterization (resonances, collinear emission, Coulomb etc.)- O’Mega optimized matrix element generator (recursiveness via Directed
Acyclical Graphs)
- VAMP: adaptive multi-channel Monte Carlo integrator- CIRCE1/2: generator/simulation tool for lepton collider beam spectra - Lepton beam ISR Kuraev/Fadin, 2003; Skrzypek/Jadach, 1991
- Color flow formalism Stelzer/Willenbrock, 2003; Kilian/Ohl/JRR/Speckner, 2011
Interfaces to external packages for Feynman rules, hadronization, tau decays, event formats, analysis, jet clustering etc. : FastJet, GoSam, GuineaPig(++), HepMC, HOPPET, LCIO, LHAPDF(4/5/6), LoopTools, OpenLoops, PYTHIA6, [PYTHIA8], StdHep
pos1 ele2 muo3 amu4gam5 gam6
gam12 pos15 pos16 ele25 ele26 gam34muo35 muo36amu45 amu46
ele234ele256 gam345 gam346muo356 amu456
*
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J.R.Reuter WHIZARD for LC Top Physics LC Top 2015, IFIC Valencia, 1.7.2015
WHIZARD: Past and recent timeline Original scope: electroweak (multi-fermion) studies at 1.6 TeV TESLA [≈ 1998-2000]
Used for many TESLA studies and most ILC CDR and TDR, CLIC CDR and detector LoI studies (versions v1.24, v1.50, v1.95) [≈ 2002-2013]
Color flow formalism [≈2005]
Major refactoring phase I: LHC physics ➝ v2.0.0 [≈ 2007-2010]
Validation inside ATLAS and CMS [≈2011-2014]
2nd refactoring phase II: NLO automation / maintainability ➝ v2.2.0 [≈ 2012-2014]
Strong interest of CEPC study group(s) for CEPC simulations [≈ 2013-2015]
04/2015, ALCW’15 Tokyo: ILC generator group endorsed v2.2 for new mass productions
Ongoing validation for LC [ee] physics between v1.95 and v2 [until ca. 08/2015]
Special thanks to: [beam spectra, photon background, event formats, shower/hadronization]
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J.R.Reuter WHIZARD for LC Top Physics LC Top 2015, IFIC Valencia, 1.7.2015
WHIZARD: Past and recent timeline Original scope: electroweak (multi-fermion) studies at 1.6 TeV TESLA [≈ 1998-2000]
Used for many TESLA studies and most ILC CDR and TDR, CLIC CDR and detector LoI studies (versions v1.24, v1.50, v1.95) [≈ 2002-2013]
Color flow formalism [≈2005]
Major refactoring phase I: LHC physics ➝ v2.0.0 [≈ 2007-2010]
Validation inside ATLAS and CMS [≈2011-2014]
2nd refactoring phase II: NLO automation / maintainability ➝ v2.2.0 [≈ 2012-2014]
Strong interest of CEPC study group(s) for CEPC simulations [≈ 2013-2015]
04/2015, ALCW’15 Tokyo: ILC generator group endorsed v2.2 for new mass productions
Ongoing validation for LC [ee] physics between v1.95 and v2 [until ca. 08/2015]
Special thanks to: [beam spectra, photon background, event formats, shower/hadronization]
Mikael Berggren Jean-Jacques Blaising Moritz Habermehl
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J.R.Reuter WHIZARD for LC Top Physics LC Top 2015, IFIC Valencia, 1.7.2015
General structure of SINDARIN input
LCWS ’14, Belgrade, Simulation summary talk:
WHIZARD Task to implement LCIO formatmodel = NMSSM
alias ll = “e-“:”e+”:”mu+”:”mu-“ alias parton = u:U:d:D:s:S:g alias jet = parton alias stop = st1:st2:ST1:ST2
process susyprod = parton, parton => stop,stop + gg,gg + gg,stop
sqrts = 13000 GeV beams = p, p => lhapdf
integrate (susyprod) { iterations = 15:500000, 5:1000000 }
n_events = 10000
sample_format = lhef, stdhep, hepmc sample = “susydata”
simulate (susyprod)
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J.R.Reuter WHIZARD for LC Top Physics LC Top 2015, IFIC Valencia, 1.7.2015
General structure of SINDARIN input
LCWS ’14, Belgrade, Simulation summary talk:
WHIZARD Task to implement LCIO format
WHIZARD v2.2.4, 02/2015:
sample_format = lcio
simulate (<process>)
model = NMSSM
alias ll = “e-“:”e+”:”mu+”:”mu-“ alias parton = u:U:d:D:s:S:g alias jet = parton alias stop = st1:st2:ST1:ST2
process susyprod = parton, parton => stop,stop + gg,gg + gg,stop
sqrts = 13000 GeV beams = p, p => lhapdf
integrate (susyprod) { iterations = 15:500000, 5:1000000 }
n_events = 10000
sample_format = lhef, stdhep, hepmc sample = “susydata”
simulate (susyprod)
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J.R.Reuter WHIZARD for LC Top Physics LC Top 2015, IFIC Valencia, 1.7.2015
General structure of SINDARIN input
LCWS ’14, Belgrade, Simulation summary talk:
WHIZARD Task to implement LCIO format
WHIZARD v2.2.4, 02/2015:
sample_format = lcio
simulate (<process>)
model = NMSSM
alias ll = “e-“:”e+”:”mu+”:”mu-“ alias parton = u:U:d:D:s:S:g alias jet = parton alias stop = st1:st2:ST1:ST2
process susyprod = parton, parton => stop,stop + gg,gg + gg,stop
sqrts = 13000 GeV beams = p, p => lhapdf
integrate (susyprod) { iterations = 15:500000, 5:1000000 }
n_events = 10000
sample_format = lhef, stdhep, hepmc sample = “susydata”
simulate (susyprod)
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J.R.Reuter WHIZARD for LC Top Physics LC Top 2015, IFIC Valencia, 1.7.2015
BSM Models in WHIZARDMODEL TYPE with CKM matrix trivial CKMQED with e, µ, ⌧, � – QED
QCD with d, u, s, c, b, t, g – QCD
Standard Model SM CKM SM
SM with anomalous gauge coupl. SM ac CKM SM ac
SM with anomalous top coupl. SMtop CKM SMtop
SM for e+e� top threshold — SM tt threshold
SM with anom. Higgs coupl. — SM rx / NoH
SM ext. for VV scattering — SSC / SSC2/ AltH
SM ext. for unitarity limits — SM ul
SM with Z 0 — Zprime
2HDM 2HDM CKM 2HDM
MSSM MSSM CKM MSSM
MSSM with gravitinos — MSSM Grav
NMSSM NMSSM CKM NMSSM
extended SUSY models — PS/E/SSM
Littlest Higgs — Littlest
Littlest Higgs with ungauged U(1) — Littlest Eta
Littlest Higgs with T parity — Littlest Tpar
Simplest Little Higgs (anomaly-free/univ.) — Simplest[ univ]
3-site model — Threeshl
UED — UED
SM with gravitino and photino — GravTest
Augmentable SM template — Template
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J.R.Reuter WHIZARD for LC Top Physics LC Top 2015, IFIC Valencia, 1.7.2015
BSM Models in WHIZARDMODEL TYPE with CKM matrix trivial CKMQED with e, µ, ⌧, � – QED
QCD with d, u, s, c, b, t, g – QCD
Standard Model SM CKM SM
SM with anomalous gauge coupl. SM ac CKM SM ac
SM with anomalous top coupl. SMtop CKM SMtop
SM for e+e� top threshold — SM tt threshold
SM with anom. Higgs coupl. — SM rx / NoH
SM ext. for VV scattering — SSC / SSC2/ AltH
SM ext. for unitarity limits — SM ul
SM with Z 0 — Zprime
2HDM 2HDM CKM 2HDM
MSSM MSSM CKM MSSM
MSSM with gravitinos — MSSM Grav
NMSSM NMSSM CKM NMSSM
extended SUSY models — PS/E/SSM
Littlest Higgs — Littlest
Littlest Higgs with ungauged U(1) — Littlest Eta
Littlest Higgs with T parity — Littlest Tpar
Simplest Little Higgs (anomaly-free/univ.) — Simplest[ univ]
3-site model — Threeshl
UED — UED
SM with gravitino and photino — GravTest
Augmentable SM template — Template
Automated models: interface to SARAH/BSM Toolbox Staub, 0909.2863; Ohl/Porod/Staub/Speckner, 1109.5147
Automated models: interface to FeynRules Christensen/Duhr; Christensen/Duhr/Fuks/JRR/Speckner, 1010.3251
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J.R.Reuter WHIZARD for LC Top Physics LC Top 2015, IFIC Valencia, 1.7.2015
BSM Models in WHIZARDMODEL TYPE with CKM matrix trivial CKMQED with e, µ, ⌧, � – QED
QCD with d, u, s, c, b, t, g – QCD
Standard Model SM CKM SM
SM with anomalous gauge coupl. SM ac CKM SM ac
SM with anomalous top coupl. SMtop CKM SMtop
SM for e+e� top threshold — SM tt threshold
SM with anom. Higgs coupl. — SM rx / NoH
SM ext. for VV scattering — SSC / SSC2/ AltH
SM ext. for unitarity limits — SM ul
SM with Z 0 — Zprime
2HDM 2HDM CKM 2HDM
MSSM MSSM CKM MSSM
MSSM with gravitinos — MSSM Grav
NMSSM NMSSM CKM NMSSM
extended SUSY models — PS/E/SSM
Littlest Higgs — Littlest
Littlest Higgs with ungauged U(1) — Littlest Eta
Littlest Higgs with T parity — Littlest Tpar
Simplest Little Higgs (anomaly-free/univ.) — Simplest[ univ]
3-site model — Threeshl
UED — UED
SM with gravitino and photino — GravTest
Augmentable SM template — Template
Automated models: interface to SARAH/BSM Toolbox Staub, 0909.2863; Ohl/Porod/Staub/Speckner, 1109.5147
Automated models: interface to FeynRules Christensen/Duhr; Christensen/Duhr/Fuks/JRR/Speckner, 1010.3251
Automated models: UFO interface [in connection with new WHIZARD/O’Mega model format]
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J.R.Reuter WHIZARD for LC Top Physics LC Top 2015, IFIC Valencia, 1.7.2015
Phase Space SetupWHIZARD algorithm: heuristics to classify phase-space topology, adaptive multi-channel
mapping ⟹ resonant, t-channel, radiation, infrared, collinear, off-shell
Complicated processes: factorization into production and decay with the unstable option
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J.R.Reuter WHIZARD for LC Top Physics LC Top 2015, IFIC Valencia, 1.7.2015
Decay processes / auto_decays
WHIZARD cannot only do scattering processes, but also decays
Example Energy distribution electron in muon decay:model = SM process mudec = e2 => e1, N1, n2 integrate (mudec)
histogram e_e1 (0, 60 MeV, 1 MeV) analysis = record e_e1 (eval E [e1])
n_events = 100000
simulate (mudec)
compile_analysis { $out_file = “test.dat” }
dN/dEe(µ� ! e�⌫̄e⌫µ)
GeV
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J.R.Reuter WHIZARD for LC Top Physics LC Top 2015, IFIC Valencia, 1.7.2015
Decay processes / auto_decays
WHIZARD cannot only do scattering processes, but also decays
Example Energy distribution electron in muon decay:model = SM process mudec = e2 => e1, N1, n2 integrate (mudec)
histogram e_e1 (0, 60 MeV, 1 MeV) analysis = record e_e1 (eval E [e1])
n_events = 100000
simulate (mudec)
compile_analysis { $out_file = “test.dat” }
auto_decays_multiplicity = 2 ?auto_decays_radiative = false
unstable Wp () { ?auto_decays = true }
Automatic integration of particle decays
dN/dEe(µ� ! e�⌫̄e⌫µ)
GeV
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J.R.Reuter WHIZARD for LC Top Physics LC Top 2015, IFIC Valencia, 1.7.2015
Spin Correlation and Polarization in CascadesCascade decay, factorize production and decay
0
200
400
600
800
0 200 400 600Minv(jℓ)
#evt/bin
0
200
400
600
800
1000
0 200 400 600Minv(jℓ)
#evt/bin
0
200
400
600
800
0 200 400 600Minv(jℓ)
#evt/binsimulate (fullproc)
0
200
400
600
800
0 200 400 600Minv(jℓ)
#evt/binsimulate (casc)
?diagonal_decay = true ?isotropic_decay = true
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J.R.Reuter WHIZARD for LC Top Physics LC Top 2015, IFIC Valencia, 1.7.2015
Spin Correlation and Polarization in CascadesCascade decay, factorize production and decay
0
200
400
600
800
0 200 400 600Minv(jℓ)
#evt/bin
0
200
400
600
800
1000
0 200 400 600Minv(jℓ)
#evt/bin
0
200
400
600
800
0 200 400 600Minv(jℓ)
#evt/binsimulate (fullproc)
0
200
400
600
800
0 200 400 600Minv(jℓ)
#evt/binsimulate (casc)
?diagonal_decay = true ?isotropic_decay = true
unstable “W+” { decay_helicity = 0 }NEW: possibility to select specific helicity in decays!
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J.R.Reuter WHIZARD for LC Top Physics LC Top 2015, IFIC Valencia, 1.7.2015
Why care about beamstrahlung / ISR ?
dσ
dMmiss
[fb/GeV] e+e− → bb̄χ̃01χ̃
01
0.01
0.1
1
0 200 400 600 800Mmiss [GeV]
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J.R.Reuter WHIZARD for LC Top Physics LC Top 2015, IFIC Valencia, 1.7.2015
Why care about beamstrahlung / ISR ?
dσ
dMmiss
[fb/GeV] e+e− → bb̄χ̃01χ̃
01
w. ISR + beamstr.
0.01
0.1
1
0 200 400 600 800Mmiss [GeV]
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J.R.Reuter WHIZARD for LC Top Physics LC Top 2015, IFIC Valencia, 1.7.2015
Lepton Collider Beam Simulation
10−810−610−40.01
0
0.002
0.004
0.006
1− xe±
Tesla,√
s = 500GeV
xe±=
.975819346
• Another demand: adapt GuineaPig beam spectra for WHIZARD v2 • For WHIZARD v1.95 simulations done by Lumilinker [T. Barklow]• TESLA/SLC spectra were rather simple• Fits with 6 or 7 parameters possible [CIRCE1]• Beams not factorizable: • No simple power law:
DB1B2(x1, x2) 6= DB1(x1) ·DB2(x2)
DB1B2(x1, x2) 6= x
↵11 (1� x1)
�1x
↵22 (1� x2)
�2
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J.R.Reuter WHIZARD for LC Top Physics LC Top 2015, IFIC Valencia, 1.7.2015
Lepton Collider Beam Simulation
10−810−610−40.01
0
0.002
0.004
0.006
1− xe±
Tesla,√
s = 500GeV
xe±=
.975819346
• Another demand: adapt GuineaPig beam spectra for WHIZARD v2 • For WHIZARD v1.95 simulations done by Lumilinker [T. Barklow]• TESLA/SLC spectra were rather simple• Fits with 6 or 7 parameters possible [CIRCE1]• Beams not factorizable: • No simple power law:
DB1B2(x1, x2) 6= DB1(x1) ·DB2(x2)
DB1B2(x1, x2) 6= x
↵11 (1� x1)
�1x
↵22 (1� x2)
�2
Dalena/Esbjerg/Schulte [LCWS 2011]
Tails @ CLIC much more complicated (wakefields)
![Page 25: The Event Generator WHIZARD for LC Top Physics - DESYreuter/downloads/LCTop2015.pdf · The Event Generator WHIZARD for LC Top Physics. J.R.Reuter WHIZARD for LC Top Physics LC Top](https://reader030.fdocuments.net/reader030/viewer/2022041223/5e0d88df4fc1b732724fe102/html5/thumbnails/25.jpg)
J.R.Reuter WHIZARD for LC Top Physics LC Top 2015, IFIC Valencia, 1.7.2015
Lepton Collider Beam Simulation
10−810−610−40.01
0
0.002
0.004
0.006
1− xe±
Tesla,√
s = 500GeV
xe±=
.975819346
• Another demand: adapt GuineaPig beam spectra for WHIZARD v2 • For WHIZARD v1.95 simulations done by Lumilinker [T. Barklow]• TESLA/SLC spectra were rather simple• Fits with 6 or 7 parameters possible [CIRCE1]• Beams not factorizable: • No simple power law:
DB1B2(x1, x2) 6= DB1(x1) ·DB2(x2)
DB1B2(x1, x2) 6= x
↵11 (1� x1)
�1x
↵22 (1� x2)
�2
Dalena/Esbjerg/Schulte [LCWS 2011]
Tails @ CLIC much more complicated (wakefields)
CIRCE2 algorithm (WHIZARD 2.2.5, 02/15)
Adapt 2D factorized variable width histogram to steep part of distributionSmooth correlated fluctuations with moderate Gaussian filter [suppresses artifacts from limited GuineaPig statisticsSmooth continuum/boundary bins separately [avoid artificial beam energy spread]
![Page 26: The Event Generator WHIZARD for LC Top Physics - DESYreuter/downloads/LCTop2015.pdf · The Event Generator WHIZARD for LC Top Physics. J.R.Reuter WHIZARD for LC Top Physics LC Top](https://reader030.fdocuments.net/reader030/viewer/2022041223/5e0d88df4fc1b732724fe102/html5/thumbnails/26.jpg)
J.R.Reuter WHIZARD for LC Top Physics LC Top 2015, IFIC Valencia, 1.7.2015
Workflow GuineaPig/CIRCE2/WHIZARD
![Page 27: The Event Generator WHIZARD for LC Top Physics - DESYreuter/downloads/LCTop2015.pdf · The Event Generator WHIZARD for LC Top Physics. J.R.Reuter WHIZARD for LC Top Physics LC Top](https://reader030.fdocuments.net/reader030/viewer/2022041223/5e0d88df4fc1b732724fe102/html5/thumbnails/27.jpg)
J.R.Reuter WHIZARD for LC Top Physics LC Top 2015, IFIC Valencia, 1.7.2015
Workflow GuineaPig/CIRCE2/WHIZARD
3 simulation options
1. Unpolarized simulation with unpol. spectra2. Pol. simulation: unpol. spectra + pol. beams 3.Polarized spectrum with helicity luminosities
![Page 28: The Event Generator WHIZARD for LC Top Physics - DESYreuter/downloads/LCTop2015.pdf · The Event Generator WHIZARD for LC Top Physics. J.R.Reuter WHIZARD for LC Top Physics LC Top](https://reader030.fdocuments.net/reader030/viewer/2022041223/5e0d88df4fc1b732724fe102/html5/thumbnails/28.jpg)
J.R.Reuter WHIZARD for LC Top Physics LC Top 2015, IFIC Valencia, 1.7.2015
Iterations of Beam Spectrum
(171,306 GuineaPig events in 10,000 bins)
![Page 29: The Event Generator WHIZARD for LC Top Physics - DESYreuter/downloads/LCTop2015.pdf · The Event Generator WHIZARD for LC Top Physics. J.R.Reuter WHIZARD for LC Top Physics LC Top](https://reader030.fdocuments.net/reader030/viewer/2022041223/5e0d88df4fc1b732724fe102/html5/thumbnails/29.jpg)
J.R.Reuter WHIZARD for LC Top Physics LC Top 2015, IFIC Valencia, 1.7.2015
Iterations of Beam Spectrum
![Page 30: The Event Generator WHIZARD for LC Top Physics - DESYreuter/downloads/LCTop2015.pdf · The Event Generator WHIZARD for LC Top Physics. J.R.Reuter WHIZARD for LC Top Physics LC Top](https://reader030.fdocuments.net/reader030/viewer/2022041223/5e0d88df4fc1b732724fe102/html5/thumbnails/30.jpg)
J.R.Reuter WHIZARD for LC Top Physics LC Top 2015, IFIC Valencia, 1.7.2015
WHIZARD Parton ShowerTwo independent implementations: kT-ordered QCD and Analytic QCD showerAnalytic shower: no shower veto ⇒ exact shower history known, allows reweighting
Technical overhaul of the shower / merging partPlans: implement GKS matching, QED shower (also interleaved, infrastructure ready)
Kilian/JRR/Schmidt/Wiesler, JHEP 1204 013 (2012)
![Page 31: The Event Generator WHIZARD for LC Top Physics - DESYreuter/downloads/LCTop2015.pdf · The Event Generator WHIZARD for LC Top Physics. J.R.Reuter WHIZARD for LC Top Physics LC Top](https://reader030.fdocuments.net/reader030/viewer/2022041223/5e0d88df4fc1b732724fe102/html5/thumbnails/31.jpg)
J.R.Reuter WHIZARD for LC Top Physics LC Top 2015, IFIC Valencia, 1.7.2015
WHIZARD Parton ShowerTwo independent implementations: kT-ordered QCD and Analytic QCD showerAnalytic shower: no shower veto ⇒ exact shower history known, allows reweighting
Technical overhaul of the shower / merging partPlans: implement GKS matching, QED shower (also interleaved, infrastructure ready)
Kilian/JRR/Schmidt/Wiesler, JHEP 1204 013 (2012)
![Page 32: The Event Generator WHIZARD for LC Top Physics - DESYreuter/downloads/LCTop2015.pdf · The Event Generator WHIZARD for LC Top Physics. J.R.Reuter WHIZARD for LC Top Physics LC Top](https://reader030.fdocuments.net/reader030/viewer/2022041223/5e0d88df4fc1b732724fe102/html5/thumbnails/32.jpg)
J.R.Reuter WHIZARD for LC Top Physics LC Top 2015, IFIC Valencia, 1.7.2015
2) Fixed-order NLO automation & POWHEG matching
in WHIZARD
![Page 33: The Event Generator WHIZARD for LC Top Physics - DESYreuter/downloads/LCTop2015.pdf · The Event Generator WHIZARD for LC Top Physics. J.R.Reuter WHIZARD for LC Top Physics LC Top](https://reader030.fdocuments.net/reader030/viewer/2022041223/5e0d88df4fc1b732724fe102/html5/thumbnails/33.jpg)
J.R.Reuter WHIZARD for LC Top Physics LC Top 2015, IFIC Valencia, 1.7.2015
NLO Development in WHIZARD
Need for precision predictions that match (sub-) percent experimental accuracy
mainly NLO corrections, but also QED and electroweak (ee)
Binoth Les Houches Interface (BLHA): Workflow
1. Process definition in SINDARIN (contract to One-Loop Program [OLP])2. OLP generates code (Born/virtual interference), WHIZARD reads contract3. NLO matrix element library loaded into WHIZARD
![Page 34: The Event Generator WHIZARD for LC Top Physics - DESYreuter/downloads/LCTop2015.pdf · The Event Generator WHIZARD for LC Top Physics. J.R.Reuter WHIZARD for LC Top Physics LC Top](https://reader030.fdocuments.net/reader030/viewer/2022041223/5e0d88df4fc1b732724fe102/html5/thumbnails/34.jpg)
J.R.Reuter WHIZARD for LC Top Physics LC Top 2015, IFIC Valencia, 1.7.2015
NLO Development in WHIZARD
Need for precision predictions that match (sub-) percent experimental accuracy
mainly NLO corrections, but also QED and electroweak (ee)
Binoth Les Houches Interface (BLHA): Workflow
1. Process definition in SINDARIN (contract to One-Loop Program [OLP])2. OLP generates code (Born/virtual interference), WHIZARD reads contract3. NLO matrix element library loaded into WHIZARD
Working NLO interfaces to: ★ GoSam [G. Cullen et al.] ★ OpenLoops [F. Cascioli et al.] (first focus on QCD corrections)
![Page 35: The Event Generator WHIZARD for LC Top Physics - DESYreuter/downloads/LCTop2015.pdf · The Event Generator WHIZARD for LC Top Physics. J.R.Reuter WHIZARD for LC Top Physics LC Top](https://reader030.fdocuments.net/reader030/viewer/2022041223/5e0d88df4fc1b732724fe102/html5/thumbnails/35.jpg)
J.R.Reuter WHIZARD for LC Top Physics LC Top 2015, IFIC Valencia, 1.7.2015
NLO Development in WHIZARD
Need for precision predictions that match (sub-) percent experimental accuracy
mainly NLO corrections, but also QED and electroweak (ee)
Binoth Les Houches Interface (BLHA): Workflow
1. Process definition in SINDARIN (contract to One-Loop Program [OLP])2. OLP generates code (Born/virtual interference), WHIZARD reads contract3. NLO matrix element library loaded into WHIZARD
Working NLO interfaces to: ★ GoSam [G. Cullen et al.] ★ OpenLoops [F. Cascioli et al.] (first focus on QCD corrections)
WHIZARD v2.2.6 contains alpha version
QCD corrections (massless and massive emitters)
alpha_power = 2 alphas_power = 0
process eett = e1,E1 => t, tbar { nlo_calculation = “full” }
![Page 36: The Event Generator WHIZARD for LC Top Physics - DESYreuter/downloads/LCTop2015.pdf · The Event Generator WHIZARD for LC Top Physics. J.R.Reuter WHIZARD for LC Top Physics LC Top](https://reader030.fdocuments.net/reader030/viewer/2022041223/5e0d88df4fc1b732724fe102/html5/thumbnails/36.jpg)
J.R.Reuter WHIZARD for LC Top Physics LC Top 2015, IFIC Valencia, 1.7.2015
NLO Development in WHIZARD
Need for precision predictions that match (sub-) percent experimental accuracy
mainly NLO corrections, but also QED and electroweak (ee)
Binoth Les Houches Interface (BLHA): Workflow
1. Process definition in SINDARIN (contract to One-Loop Program [OLP])2. OLP generates code (Born/virtual interference), WHIZARD reads contract3. NLO matrix element library loaded into WHIZARD
Working NLO interfaces to: ★ GoSam [G. Cullen et al.] ★ OpenLoops [F. Cascioli et al.] (first focus on QCD corrections)
WHIZARD v2.2.6 contains alpha version
QCD corrections (massless and massive emitters)
alpha_power = 2 alphas_power = 0
process eett = e1,E1 => t, tbar { nlo_calculation = “full” }
![Page 37: The Event Generator WHIZARD for LC Top Physics - DESYreuter/downloads/LCTop2015.pdf · The Event Generator WHIZARD for LC Top Physics. J.R.Reuter WHIZARD for LC Top Physics LC Top](https://reader030.fdocuments.net/reader030/viewer/2022041223/5e0d88df4fc1b732724fe102/html5/thumbnails/37.jpg)
J.R.Reuter WHIZARD for LC Top Physics LC Top 2015, IFIC Valencia, 1.7.2015
NLO Development in WHIZARD
Need for precision predictions that match (sub-) percent experimental accuracy
mainly NLO corrections, but also QED and electroweak (ee)
Binoth Les Houches Interface (BLHA): Workflow
1. Process definition in SINDARIN (contract to One-Loop Program [OLP])2. OLP generates code (Born/virtual interference), WHIZARD reads contract3. NLO matrix element library loaded into WHIZARD
Working NLO interfaces to: ★ GoSam [G. Cullen et al.] ★ OpenLoops [F. Cascioli et al.] (first focus on QCD corrections)
WHIZARD v2.2.6 contains alpha version
QCD corrections (massless and massive emitters)
alpha_power = 2 alphas_power = 0
process eett = e1,E1 => t, tbar { nlo_calculation = “full” }
![Page 38: The Event Generator WHIZARD for LC Top Physics - DESYreuter/downloads/LCTop2015.pdf · The Event Generator WHIZARD for LC Top Physics. J.R.Reuter WHIZARD for LC Top Physics LC Top](https://reader030.fdocuments.net/reader030/viewer/2022041223/5e0d88df4fc1b732724fe102/html5/thumbnails/38.jpg)
J.R.Reuter WHIZARD for LC Top Physics LC Top 2015, IFIC Valencia, 1.7.2015
NLO Development in WHIZARD
Need for precision predictions that match (sub-) percent experimental accuracy
mainly NLO corrections, but also QED and electroweak (ee)
Binoth Les Houches Interface (BLHA): Workflow
1. Process definition in SINDARIN (contract to One-Loop Program [OLP])2. OLP generates code (Born/virtual interference), WHIZARD reads contract3. NLO matrix element library loaded into WHIZARD
Working NLO interfaces to: ★ GoSam [G. Cullen et al.] ★ OpenLoops [F. Cascioli et al.] (first focus on QCD corrections)
WHIZARD v2.2.6 contains alpha version
QCD corrections (massless and massive emitters)
alpha_power = 2 alphas_power = 0
process eett = e1,E1 => t, tbar { nlo_calculation = “full” }
![Page 39: The Event Generator WHIZARD for LC Top Physics - DESYreuter/downloads/LCTop2015.pdf · The Event Generator WHIZARD for LC Top Physics. J.R.Reuter WHIZARD for LC Top Physics LC Top](https://reader030.fdocuments.net/reader030/viewer/2022041223/5e0d88df4fc1b732724fe102/html5/thumbnails/39.jpg)
J.R.Reuter WHIZARD for LC Top Physics LC Top 2015, IFIC Valencia, 1.7.2015
FKS Subtraction (Frixione/Kunszt/Signer)
Subtraction formalism to make real and virtual contributions separately finite
d�NLO =
Z
n+1
�d�R � d�S
�
| {z }finite
+
Z
n+1
d�S +
Z
nd�V
| {z }finite
![Page 40: The Event Generator WHIZARD for LC Top Physics - DESYreuter/downloads/LCTop2015.pdf · The Event Generator WHIZARD for LC Top Physics. J.R.Reuter WHIZARD for LC Top Physics LC Top](https://reader030.fdocuments.net/reader030/viewer/2022041223/5e0d88df4fc1b732724fe102/html5/thumbnails/40.jpg)
J.R.Reuter WHIZARD for LC Top Physics LC Top 2015, IFIC Valencia, 1.7.2015
FKS Subtraction (Frixione/Kunszt/Signer)
Subtraction formalism to make real and virtual contributions separately finite
d�NLO =
Z
n+1
�d�R � d�S
�
| {z }finite
+
Z
n+1
d�S +
Z
nd�V
| {z }finite
✴ Find all singular pairs
✴ Partition phase space according to singular regions
✴ Generate subtraction terms for singular regions
I = {(1, 5), (1, 6), (2, 5), (2, 6), (5, 6)}
1 =X
↵2IS↵(�)
Automated subtraction terms in WHIZARD, algorithm:
![Page 41: The Event Generator WHIZARD for LC Top Physics - DESYreuter/downloads/LCTop2015.pdf · The Event Generator WHIZARD for LC Top Physics. J.R.Reuter WHIZARD for LC Top Physics LC Top](https://reader030.fdocuments.net/reader030/viewer/2022041223/5e0d88df4fc1b732724fe102/html5/thumbnails/41.jpg)
J.R.Reuter WHIZARD for LC Top Physics LC Top 2015, IFIC Valencia, 1.7.2015
FKS Subtraction (Frixione/Kunszt/Signer)
Subtraction formalism to make real and virtual contributions separately finite
d�NLO =
Z
n+1
�d�R � d�S
�
| {z }finite
+
Z
n+1
d�S +
Z
nd�V
| {z }finite
✴ Find all singular pairs
✴ Partition phase space according to singular regions
✴ Generate subtraction terms for singular regions
I = {(1, 5), (1, 6), (2, 5), (2, 6), (5, 6)}
1 =X
↵2IS↵(�)
Automated subtraction terms in WHIZARD, algorithm:
![Page 42: The Event Generator WHIZARD for LC Top Physics - DESYreuter/downloads/LCTop2015.pdf · The Event Generator WHIZARD for LC Top Physics. J.R.Reuter WHIZARD for LC Top Physics LC Top](https://reader030.fdocuments.net/reader030/viewer/2022041223/5e0d88df4fc1b732724fe102/html5/thumbnails/42.jpg)
J.R.Reuter WHIZARD for LC Top Physics LC Top 2015, IFIC Valencia, 1.7.2015
Examples and Validation
Simplest benchmark process:
e+e� ! qq̄ with��NLO � �LO
�/�LO = ↵s/⇡
Plot for total cross section for fixed strong coupling constant
List of validated QCD NLO processes
• Cross-checks with MG5_aMC@NLO
• Phase space integration for virtuals performs great
• e+e� ! qq̄
• e+e� ! qq̄g
• e+e� ! `+`�qq̄
• e+e� ! `+⌫`qq̄
• e+e� ! tt̄
• e+e� ! tW�b
• e+e� ! W+W�bb̄
• e+e� ! tt̄H
![Page 43: The Event Generator WHIZARD for LC Top Physics - DESYreuter/downloads/LCTop2015.pdf · The Event Generator WHIZARD for LC Top Physics. J.R.Reuter WHIZARD for LC Top Physics LC Top](https://reader030.fdocuments.net/reader030/viewer/2022041223/5e0d88df4fc1b732724fe102/html5/thumbnails/43.jpg)
J.R.Reuter WHIZARD for LC Top Physics LC Top 2015, IFIC Valencia, 1.7.2015
Examples and Validation
Simplest benchmark process:
e+e� ! qq̄ with��NLO � �LO
�/�LO = ↵s/⇡
Plot for total cross section for fixed strong coupling constant
List of validated QCD NLO processes
• Cross-checks with MG5_aMC@NLO
• Phase space integration for virtuals performs great
✦ QCD NLO infrastructure in pp almost complete
✦ First attempts on electroweak corrections, interfacing the RECOLA code [Denner et al.]
• e+e� ! qq̄
• e+e� ! qq̄g
• e+e� ! `+`�qq̄
• e+e� ! `+⌫`qq̄
• e+e� ! tt̄
• e+e� ! tW�b
• e+e� ! W+W�bb̄
• e+e� ! tt̄H
![Page 44: The Event Generator WHIZARD for LC Top Physics - DESYreuter/downloads/LCTop2015.pdf · The Event Generator WHIZARD for LC Top Physics. J.R.Reuter WHIZARD for LC Top Physics LC Top](https://reader030.fdocuments.net/reader030/viewer/2022041223/5e0d88df4fc1b732724fe102/html5/thumbnails/44.jpg)
J.R.Reuter WHIZARD for LC Top Physics LC Top 2015, IFIC Valencia, 1.7.2015
NLO Fixed-Order EventsAdd weights of real emission events to weight of Born kinematics using the FKS mappingOutput weighted events in WHIZARD (e.g. using HepMC), then analysis with Rivet Example process: e+e� ! W+W�bb̄
mWb [GeV] mWb [GeV]
![Page 45: The Event Generator WHIZARD for LC Top Physics - DESYreuter/downloads/LCTop2015.pdf · The Event Generator WHIZARD for LC Top Physics. J.R.Reuter WHIZARD for LC Top Physics LC Top](https://reader030.fdocuments.net/reader030/viewer/2022041223/5e0d88df4fc1b732724fe102/html5/thumbnails/45.jpg)
J.R.Reuter WHIZARD for LC Top Physics LC Top 2015, IFIC Valencia, 1.7.2015
NLO Fixed-Order EventsAdd weights of real emission events to weight of Born kinematics using the FKS mappingOutput weighted events in WHIZARD (e.g. using HepMC), then analysis with Rivet Example process: e+e� ! W+W�bb̄
![Page 46: The Event Generator WHIZARD for LC Top Physics - DESYreuter/downloads/LCTop2015.pdf · The Event Generator WHIZARD for LC Top Physics. J.R.Reuter WHIZARD for LC Top Physics LC Top](https://reader030.fdocuments.net/reader030/viewer/2022041223/5e0d88df4fc1b732724fe102/html5/thumbnails/46.jpg)
J.R.Reuter WHIZARD for LC Top Physics LC Top 2015, IFIC Valencia, 1.7.2015
NLO Fixed-Order EventsAdd weights of real emission events to weight of Born kinematics using the FKS mappingOutput weighted events in WHIZARD (e.g. using HepMC), then analysis with Rivet Example process: e+e� ! W+W�bb̄
Next steps: produce polarized results (remember: ILC will always run with polarization)Produce also plots including complete ISR photon radiation and beamstrahlungInvestigate the full 2 ➝ 6 process: e+e- ➝ bbeμνν [Chokoufé/Kilian/Lindert/JRR/Pozzorini/Weiss]
![Page 47: The Event Generator WHIZARD for LC Top Physics - DESYreuter/downloads/LCTop2015.pdf · The Event Generator WHIZARD for LC Top Physics. J.R.Reuter WHIZARD for LC Top Physics LC Top](https://reader030.fdocuments.net/reader030/viewer/2022041223/5e0d88df4fc1b732724fe102/html5/thumbnails/47.jpg)
J.R.Reuter WHIZARD for LC Top Physics LC Top 2015, IFIC Valencia, 1.7.2015
Automated POWHEG Matching in WHIZARD
Soft gluon emissions before hard emission generate large logsPerturbative αs : Consistent matching of NLO matrix element with showerPOWHEG method: hardest emission first [Nason et al.]
|Msoft
|2 ⇠ 1
k2T! log
kmax
T
kmin
T
![Page 48: The Event Generator WHIZARD for LC Top Physics - DESYreuter/downloads/LCTop2015.pdf · The Event Generator WHIZARD for LC Top Physics. J.R.Reuter WHIZARD for LC Top Physics LC Top](https://reader030.fdocuments.net/reader030/viewer/2022041223/5e0d88df4fc1b732724fe102/html5/thumbnails/48.jpg)
J.R.Reuter WHIZARD for LC Top Physics LC Top 2015, IFIC Valencia, 1.7.2015
Automated POWHEG Matching in WHIZARD
Soft gluon emissions before hard emission generate large logsPerturbative αs : Consistent matching of NLO matrix element with showerPOWHEG method: hardest emission first [Nason et al.]
|Msoft
|2 ⇠ 1
k2T! log
kmax
T
kmin
T
• Complete NLO events
• POWHEG generate events according to the formula:
• Uses the modified Sudakov form factor:
B(�n) = B(�n) + V (�n) +
Zd�radR(�n+1)
d� = B(�n)
�NLO
R (kminT ) +�NLO
R (kT )R(�n+1)
B(�n)d�rad
�
�
NLOR (kT ) = exp
�Z
d�radR(�n+1)
B(�n)✓(kT (�n+1)� kT )
�
![Page 49: The Event Generator WHIZARD for LC Top Physics - DESYreuter/downloads/LCTop2015.pdf · The Event Generator WHIZARD for LC Top Physics. J.R.Reuter WHIZARD for LC Top Physics LC Top](https://reader030.fdocuments.net/reader030/viewer/2022041223/5e0d88df4fc1b732724fe102/html5/thumbnails/49.jpg)
J.R.Reuter WHIZARD for LC Top Physics LC Top 2015, IFIC Valencia, 1.7.2015
Automated POWHEG Matching in WHIZARD
Soft gluon emissions before hard emission generate large logsPerturbative αs : Consistent matching of NLO matrix element with showerPOWHEG method: hardest emission first [Nason et al.]
|Msoft
|2 ⇠ 1
k2T! log
kmax
T
kmin
T
• Complete NLO events
• POWHEG generate events according to the formula:
• Uses the modified Sudakov form factor:
B(�n) = B(�n) + V (�n) +
Zd�radR(�n+1)
d� = B(�n)
�NLO
R (kminT ) +�NLO
R (kT )R(�n+1)
B(�n)d�rad
�
�
NLOR (kT ) = exp
�Z
d�radR(�n+1)
B(�n)✓(kT (�n+1)� kT )
�
Hardest emission: ; shower with imposing a veto if virtual and real terms larger than Born: shouldn’t happen in perturbative regions Reweighting such that for all events POWHEG: Positive Weight Hardest Emission Generator own implementation in WHIZARD
kmax
T
B < 0
B > 0
![Page 50: The Event Generator WHIZARD for LC Top Physics - DESYreuter/downloads/LCTop2015.pdf · The Event Generator WHIZARD for LC Top Physics. J.R.Reuter WHIZARD for LC Top Physics LC Top](https://reader030.fdocuments.net/reader030/viewer/2022041223/5e0d88df4fc1b732724fe102/html5/thumbnails/50.jpg)
J.R.Reuter WHIZARD for LC Top Physics LC Top 2015, IFIC Valencia, 1.7.2015
POWHEG Matching, example: e+e- to dijets
![Page 51: The Event Generator WHIZARD for LC Top Physics - DESYreuter/downloads/LCTop2015.pdf · The Event Generator WHIZARD for LC Top Physics. J.R.Reuter WHIZARD for LC Top Physics LC Top](https://reader030.fdocuments.net/reader030/viewer/2022041223/5e0d88df4fc1b732724fe102/html5/thumbnails/51.jpg)
J.R.Reuter WHIZARD for LC Top Physics LC Top 2015, IFIC Valencia, 1.7.2015
3) Top threshold in (N)LL (p)NRQCD matched to (N)LO QCD
in WHIZARD
![Page 52: The Event Generator WHIZARD for LC Top Physics - DESYreuter/downloads/LCTop2015.pdf · The Event Generator WHIZARD for LC Top Physics. J.R.Reuter WHIZARD for LC Top Physics LC Top](https://reader030.fdocuments.net/reader030/viewer/2022041223/5e0d88df4fc1b732724fe102/html5/thumbnails/52.jpg)
J.R.Reuter WHIZARD for LC Top Physics LC Top 2015, IFIC Valencia, 1.7.2015
Top Threshold at lepton collidersILC top threshold scan best-known method to measure top quark mass, ΔΜ ~ 30-50 MeV
Heavy quark production at lepton colliders, qualitatively:
Threshold region: top velocity v ~ αs ⪡ 1
![Page 53: The Event Generator WHIZARD for LC Top Physics - DESYreuter/downloads/LCTop2015.pdf · The Event Generator WHIZARD for LC Top Physics. J.R.Reuter WHIZARD for LC Top Physics LC Top](https://reader030.fdocuments.net/reader030/viewer/2022041223/5e0d88df4fc1b732724fe102/html5/thumbnails/53.jpg)
J.R.Reuter WHIZARD for LC Top Physics LC Top 2015, IFIC Valencia, 1.7.2015
Top Threshold Resummation in (p)NRQCD
NRQCD is EFT for non-relativistic quark-antiquark systems: separate M·v and M·v Integrate out hard quark and gluon d.o.f. (for more details: Talk M. Beneke ) Resummation of singular terms close to threshold (v = 0) Hoang et al. ’99-‘01; Beneke et al., ’13-‘14
2
R ⌘ �tt̄
�µµ= v
X
k
⇣↵s
v
⌘k X
i
(↵s ln v)i ⇥
⇥�1 (LL); ↵s, v (NLL); ↵2
s,↵sv, v2 (NNLL)
Phase space of two massive particles
(p/v)NRQCD EFT w/ RG improvement
![Page 54: The Event Generator WHIZARD for LC Top Physics - DESYreuter/downloads/LCTop2015.pdf · The Event Generator WHIZARD for LC Top Physics. J.R.Reuter WHIZARD for LC Top Physics LC Top](https://reader030.fdocuments.net/reader030/viewer/2022041223/5e0d88df4fc1b732724fe102/html5/thumbnails/54.jpg)
J.R.Reuter WHIZARD for LC Top Physics LC Top 2015, IFIC Valencia, 1.7.2015
Top Threshold Resummation in (p)NRQCD
NRQCD is EFT for non-relativistic quark-antiquark systems: separate M·v and M·v Integrate out hard quark and gluon d.o.f. (for more details: Talk M. Beneke ) Resummation of singular terms close to threshold (v = 0) Hoang et al. ’99-‘01; Beneke et al., ’13-‘14
2
R ⌘ �tt̄
�µµ= v
X
k
⇣↵s
v
⌘k X
i
(↵s ln v)i ⇥
⇥�1 (LL); ↵s, v (NLL); ↵2
s,↵sv, v2 (NNLL)
Phase space of two massive particles
R�,Z(s) = F v(s)Rv(s)| {z }s-wave: LL+NLL
+ F a(s)Ra(s)| {z }p-wave⇠v2:NNLL
but contributesat NLL differentially!
(p/v)NRQCD EFT w/ RG improvement
![Page 55: The Event Generator WHIZARD for LC Top Physics - DESYreuter/downloads/LCTop2015.pdf · The Event Generator WHIZARD for LC Top Physics. J.R.Reuter WHIZARD for LC Top Physics LC Top](https://reader030.fdocuments.net/reader030/viewer/2022041223/5e0d88df4fc1b732724fe102/html5/thumbnails/55.jpg)
J.R.Reuter WHIZARD for LC Top Physics LC Top 2015, IFIC Valencia, 1.7.2015
Top Threshold Resummation in (p)NRQCD
NRQCD is EFT for non-relativistic quark-antiquark systems: separate M·v and M·v Integrate out hard quark and gluon d.o.f. (for more details: Talk M. Beneke ) Resummation of singular terms close to threshold (v = 0) Hoang et al. ’99-‘01; Beneke et al., ’13-‘14
2
R ⌘ �tt̄
�µµ= v
X
k
⇣↵s
v
⌘k X
i
(↵s ln v)i ⇥
⇥�1 (LL); ↵s, v (NLL); ↵2
s,↵sv, v2 (NNLL)
Phase space of two massive particles
Coulomb potential gluon ladder resumption
R�,Z(s) = F v(s)Rv(s)| {z }s-wave: LL+NLL
+ F a(s)Ra(s)| {z }p-wave⇠v2:NNLL
but contributesat NLL differentially!
(p/v)NRQCD EFT w/ RG improvement
![Page 56: The Event Generator WHIZARD for LC Top Physics - DESYreuter/downloads/LCTop2015.pdf · The Event Generator WHIZARD for LC Top Physics. J.R.Reuter WHIZARD for LC Top Physics LC Top](https://reader030.fdocuments.net/reader030/viewer/2022041223/5e0d88df4fc1b732724fe102/html5/thumbnails/56.jpg)
J.R.Reuter WHIZARD for LC Top Physics LC Top 2015, IFIC Valencia, 1.7.2015
Top Threshold Resummation in (p)NRQCD
NRQCD is EFT for non-relativistic quark-antiquark systems: separate M·v and M·v Integrate out hard quark and gluon d.o.f. (for more details: Talk M. Beneke ) Resummation of singular terms close to threshold (v = 0) Hoang et al. ’99-‘01; Beneke et al., ’13-‘14
2
R ⌘ �tt̄
�µµ= v
X
k
⇣↵s
v
⌘k X
i
(↵s ln v)i ⇥
⇥�1 (LL); ↵s, v (NLL); ↵2
s,↵sv, v2 (NNLL)
Phase space of two massive particles
Coulomb potential gluon ladder resumption
R�,Z(s) = F v(s)Rv(s)| {z }s-wave: LL+NLL
+ F a(s)Ra(s)| {z }p-wave⇠v2:NNLL
but contributesat NLL differentially!
| {z }
can be mapped onto effective ttV vertex
C 3 Gv/a(N)LL
= Gv/a(N)LL
(↵s,Mpole
t ,ps, |~pt| ,�t)
differential in off-shell tt phase space
far away fromthreshold
(p/v)NRQCD EFT w/ RG improvement
![Page 57: The Event Generator WHIZARD for LC Top Physics - DESYreuter/downloads/LCTop2015.pdf · The Event Generator WHIZARD for LC Top Physics. J.R.Reuter WHIZARD for LC Top Physics LC Top](https://reader030.fdocuments.net/reader030/viewer/2022041223/5e0d88df4fc1b732724fe102/html5/thumbnails/57.jpg)
J.R.Reuter WHIZARD for LC Top Physics LC Top 2015, IFIC Valencia, 1.7.2015
with F. Bach/A. Hoang/M. StahlhofenTop Threshold in WHIZARD
Implement resummed threshold effects as effective vertex [form factor] in WHIZARD from TOPPIK code [Jezabek/Teubner], included in WHIZARDGv,a(0, pt, E + i�t, ⌫)
M1S = 172GeV, �t = 1.54GeV,
↵s(MZ) = 0.118
Default parameters:
M1S = Mpole
t
(1��LL/NLL
(Coul.) )
![Page 58: The Event Generator WHIZARD for LC Top Physics - DESYreuter/downloads/LCTop2015.pdf · The Event Generator WHIZARD for LC Top Physics. J.R.Reuter WHIZARD for LC Top Physics LC Top](https://reader030.fdocuments.net/reader030/viewer/2022041223/5e0d88df4fc1b732724fe102/html5/thumbnails/58.jpg)
J.R.Reuter WHIZARD for LC Top Physics LC Top 2015, IFIC Valencia, 1.7.2015
with F. Bach/A. Hoang/M. StahlhofenTop Threshold in WHIZARD
Implement resummed threshold effects as effective vertex [form factor] in WHIZARD from TOPPIK code [Jezabek/Teubner], included in WHIZARDGv,a(0, pt, E + i�t, ⌫)
M1S = 172GeV, �t = 1.54GeV,
↵s(MZ) = 0.118
Default parameters:
M1S = Mpole
t
(1��LL/NLL
(Coul.) )
![Page 59: The Event Generator WHIZARD for LC Top Physics - DESYreuter/downloads/LCTop2015.pdf · The Event Generator WHIZARD for LC Top Physics. J.R.Reuter WHIZARD for LC Top Physics LC Top](https://reader030.fdocuments.net/reader030/viewer/2022041223/5e0d88df4fc1b732724fe102/html5/thumbnails/59.jpg)
J.R.Reuter WHIZARD for LC Top Physics LC Top 2015, IFIC Valencia, 1.7.2015
with F. Bach/A. Hoang/M. StahlhofenTop Threshold in WHIZARD
Implement resummed threshold effects as effective vertex [form factor] in WHIZARD from TOPPIK code [Jezabek/Teubner], included in WHIZARDGv,a(0, pt, E + i�t, ⌫)
M1S = 172GeV, �t = 1.54GeV,
↵s(MZ) = 0.118
Default parameters:
M1S = Mpole
t
(1��LL/NLL
(Coul.) )
Theory uncertainties from scale variations:hard and soft scale
µh = h ·mt µs = f ·mtv
![Page 60: The Event Generator WHIZARD for LC Top Physics - DESYreuter/downloads/LCTop2015.pdf · The Event Generator WHIZARD for LC Top Physics. J.R.Reuter WHIZARD for LC Top Physics LC Top](https://reader030.fdocuments.net/reader030/viewer/2022041223/5e0d88df4fc1b732724fe102/html5/thumbnails/60.jpg)
J.R.Reuter WHIZARD for LC Top Physics LC Top 2015, IFIC Valencia, 1.7.2015
Sanity checks: correct limit for αs ⟶ 0, stable against variation of cutoff ΔM [15-30 GeV]
Why include LL/NLL in a Monte Carlo event generator? Important effects: beamstrahlung; ISR; LO electroweak terms More exclusive observables accessible
![Page 61: The Event Generator WHIZARD for LC Top Physics - DESYreuter/downloads/LCTop2015.pdf · The Event Generator WHIZARD for LC Top Physics. J.R.Reuter WHIZARD for LC Top Physics LC Top](https://reader030.fdocuments.net/reader030/viewer/2022041223/5e0d88df4fc1b732724fe102/html5/thumbnails/61.jpg)
J.R.Reuter WHIZARD for LC Top Physics LC Top 2015, IFIC Valencia, 1.7.2015
Sanity checks: correct limit for αs ⟶ 0, stable against variation of cutoff ΔM [15-30 GeV]
Why include LL/NLL in a Monte Carlo event generator? Important effects: beamstrahlung; ISR; LO electroweak terms More exclusive observables accessible
![Page 62: The Event Generator WHIZARD for LC Top Physics - DESYreuter/downloads/LCTop2015.pdf · The Event Generator WHIZARD for LC Top Physics. J.R.Reuter WHIZARD for LC Top Physics LC Top](https://reader030.fdocuments.net/reader030/viewer/2022041223/5e0d88df4fc1b732724fe102/html5/thumbnails/62.jpg)
J.R.Reuter WHIZARD for LC Top Physics LC Top 2015, IFIC Valencia, 1.7.2015
Sanity checks: correct limit for αs ⟶ 0, stable against variation of cutoff ΔM [15-30 GeV]
Why include LL/NLL in a Monte Carlo event generator? Important effects: beamstrahlung; ISR; LO electroweak terms More exclusive observables accessible
Forward-backward asymmetry(norm. ⇒ good shape stability)
Afb :=�(ptz > 0)� �(ptz) < 0)
�(ptz > 0) + �(ptz < 0)
![Page 63: The Event Generator WHIZARD for LC Top Physics - DESYreuter/downloads/LCTop2015.pdf · The Event Generator WHIZARD for LC Top Physics. J.R.Reuter WHIZARD for LC Top Physics LC Top](https://reader030.fdocuments.net/reader030/viewer/2022041223/5e0d88df4fc1b732724fe102/html5/thumbnails/63.jpg)
J.R.Reuter WHIZARD for LC Top Physics LC Top 2015, IFIC Valencia, 1.7.2015
Matching to continuum at LO and NLO
• Transition region between relativistic and resummation effects • CLIC benchmark energies:
0.38 TeV, 1.4 TeV, 3.0 TeV [Talk L. Linssen]
• Leading order approximation• non-relativistic NLL approx. using TOPPIK• relativistic NLO (ttV vertex off-shell @
NLO) [Kızılersü et al., 1995; Davydychev et al., 2000]
• nonrelativistic O(αs) expansion• NLL resummed threshold ➝ relativistic
NLO continuum matching• Soft nonrel. O(αs) corrections vanishing as
log(v) for v ➝ 1
Comparison of different approximations
LO
NLONR NLL
NR O(αs) exp.
LO
NLO
NR NLLNR O(αs) exp.
NLL/NLO matching
![Page 64: The Event Generator WHIZARD for LC Top Physics - DESYreuter/downloads/LCTop2015.pdf · The Event Generator WHIZARD for LC Top Physics. J.R.Reuter WHIZARD for LC Top Physics LC Top](https://reader030.fdocuments.net/reader030/viewer/2022041223/5e0d88df4fc1b732724fe102/html5/thumbnails/64.jpg)
J.R.Reuter WHIZARD for LC Top Physics LC Top 2015, IFIC Valencia, 1.7.2015
Matching to continuum at LO and NLO
• Transition region between relativistic and resummation effects • CLIC benchmark energies:
0.38 TeV, 1.4 TeV, 3.0 TeV [Talk L. Linssen]
• Leading order approximation• non-relativistic NLL approx. using TOPPIK• relativistic NLO (ttV vertex off-shell @
NLO) [Kızılersü et al., 1995; Davydychev et al., 2000]
• nonrelativistic O(αs) expansion• NLL resummed threshold ➝ relativistic
NLO continuum matching• Soft nonrel. O(αs) corrections vanishing as
log(v) for v ➝ 1
Comparison of different approximations
LO
NLONR NLL
NR O(αs) exp.
LO
NLO
NR NLLNR O(αs) exp.
NLL/NLO matching
![Page 65: The Event Generator WHIZARD for LC Top Physics - DESYreuter/downloads/LCTop2015.pdf · The Event Generator WHIZARD for LC Top Physics. J.R.Reuter WHIZARD for LC Top Physics LC Top](https://reader030.fdocuments.net/reader030/viewer/2022041223/5e0d88df4fc1b732724fe102/html5/thumbnails/65.jpg)
J.R.Reuter WHIZARD for LC Top Physics LC Top 2015, IFIC Valencia, 1.7.2015
Matching to continuum at LO and NLO
• Transition region between relativistic and resummation effects • CLIC benchmark energies:
0.38 TeV, 1.4 TeV, 3.0 TeV [Talk L. Linssen]
• Leading order approximation• non-relativistic NLL approx. using TOPPIK• relativistic NLO (ttV vertex off-shell @
NLO) [Kızılersü et al., 1995; Davydychev et al., 2000]
• nonrelativistic O(αs) expansion• NLL resummed threshold ➝ relativistic
NLO continuum matching• Soft nonrel. O(αs) corrections vanishing as
log(v) for v ➝ 1
Comparison of different approximations
LO
NLONR NLL
NR O(αs) exp.
LO
NLO
NR NLLNR O(αs) exp.
NLL/NLO matching
Error estimate preliminary: DON’T QUOTE !!!
LO
Total uncertainty: matching and h-f variation band
![Page 66: The Event Generator WHIZARD for LC Top Physics - DESYreuter/downloads/LCTop2015.pdf · The Event Generator WHIZARD for LC Top Physics. J.R.Reuter WHIZARD for LC Top Physics LC Top](https://reader030.fdocuments.net/reader030/viewer/2022041223/5e0d88df4fc1b732724fe102/html5/thumbnails/66.jpg)
J.R.Reuter WHIZARD for LC Top Physics LC Top 2015, IFIC Valencia, 1.7.2015
Projects, Plans, Performance and all that
O’Mega Virtual Machine (OVM): ME via bytecode interpreter than compiled code ✓ Parton shower: LO merging (MLM ✓) , NLO matching
QED shower (FSR)
QED shower (ISR); exclusive part of ISR spectrum
pT spectrum of ISR radiation
automated massless/massive QCD NLO corrections: FS ✓ / Initial state in preparation ➝ WHIZARD 3.0
QED/electroweak NLO automation: longer time scale
complete NLL NRQCD top threshold/NLO continuum matching; extension to ttH [✓]
POWHEG matching implemented ✓ ; maybe also MC@NLO or Nagy-Soper matching
Monte Carlo over helicities and colors
Modified algorithm for multi-leg (tree) matrix elements: includes high-color flow amplitudes, QCD/EW coupling orders, completely general Lorentz structures, UFO format
Automatic generation of decays (and calculation of decay widths) ✓ New syntax for nested decay chains
process = e1, E1 => (t => (Wp => E2, nu2), b), tbar
![Page 67: The Event Generator WHIZARD for LC Top Physics - DESYreuter/downloads/LCTop2015.pdf · The Event Generator WHIZARD for LC Top Physics. J.R.Reuter WHIZARD for LC Top Physics LC Top](https://reader030.fdocuments.net/reader030/viewer/2022041223/5e0d88df4fc1b732724fe102/html5/thumbnails/67.jpg)
J.R.Reuter WHIZARD for LC Top Physics LC Top 2015, IFIC Valencia, 1.7.2015
Conclusions & Outlook
WHIZARD 2.2 event generator for collider physics (ee, pp, ep)
Allows to simulate all possible BSM models
Allows for all SM backgrounds
ee physics: beamspectra, LCIO, LC top threshold
NLO automation: reals and subtraction terms (FKS) [+ virtuals
externally] ➝ WHIZARD 3.0
allows to produce NLO fixed-order histograms
Automated POWHEG matching (other schemes in progress)
Ongoing projects: Lorentz structure, showers, merging
Tell us what is missing, insufficient, annoying, desirable
![Page 68: The Event Generator WHIZARD for LC Top Physics - DESYreuter/downloads/LCTop2015.pdf · The Event Generator WHIZARD for LC Top Physics. J.R.Reuter WHIZARD for LC Top Physics LC Top](https://reader030.fdocuments.net/reader030/viewer/2022041223/5e0d88df4fc1b732724fe102/html5/thumbnails/68.jpg)
J.R.Reuter WHIZARD for LC Top Physics LC Top 2015, IFIC Valencia, 1.7.2015
Conclusions & Outlook
WHIZARD 2.2 event generator for collider physics (ee, pp, ep)
Allows to simulate all possible BSM models
Allows for all SM backgrounds
ee physics: beamspectra, LCIO, LC top threshold
NLO automation: reals and subtraction terms (FKS) [+ virtuals
externally] ➝ WHIZARD 3.0
allows to produce NLO fixed-order histograms
Automated POWHEG matching (other schemes in progress)
Ongoing projects: Lorentz structure, showers, merging
Tell us what is missing, insufficient, annoying, desirable
even if it is in a conference summary talk ⟹ Challenge accepted !
![Page 69: The Event Generator WHIZARD for LC Top Physics - DESYreuter/downloads/LCTop2015.pdf · The Event Generator WHIZARD for LC Top Physics. J.R.Reuter WHIZARD for LC Top Physics LC Top](https://reader030.fdocuments.net/reader030/viewer/2022041223/5e0d88df4fc1b732724fe102/html5/thumbnails/69.jpg)
J.R.Reuter WHIZARD for LC Top Physics LC Top 2015, IFIC Valencia, 1.7.2015
Pictorial summary: loops, legs, and subtractions
![Page 70: The Event Generator WHIZARD for LC Top Physics - DESYreuter/downloads/LCTop2015.pdf · The Event Generator WHIZARD for LC Top Physics. J.R.Reuter WHIZARD for LC Top Physics LC Top](https://reader030.fdocuments.net/reader030/viewer/2022041223/5e0d88df4fc1b732724fe102/html5/thumbnails/70.jpg)
J.R.Reuter WHIZARD for LC Top Physics LC Top 2015, IFIC Valencia, 1.7.2015
Pictorial summary: loops, legs, and subtractions
![Page 71: The Event Generator WHIZARD for LC Top Physics - DESYreuter/downloads/LCTop2015.pdf · The Event Generator WHIZARD for LC Top Physics. J.R.Reuter WHIZARD for LC Top Physics LC Top](https://reader030.fdocuments.net/reader030/viewer/2022041223/5e0d88df4fc1b732724fe102/html5/thumbnails/71.jpg)
J.R.Reuter WHIZARD for LC Top Physics LC Top 2015, IFIC Valencia, 1.7.2015
BACKUP SLIDES:
![Page 72: The Event Generator WHIZARD for LC Top Physics - DESYreuter/downloads/LCTop2015.pdf · The Event Generator WHIZARD for LC Top Physics. J.R.Reuter WHIZARD for LC Top Physics LC Top](https://reader030.fdocuments.net/reader030/viewer/2022041223/5e0d88df4fc1b732724fe102/html5/thumbnails/72.jpg)
J.R.Reuter WHIZARD for LC Top Physics LC Top 2015, IFIC Valencia, 1.7.2015
WHIZARD: Installation and Run
Download: http://www.hepforge.org/archive/whizard/whizard-2.2.6.tar.gz
Unpack it, intended to be installed in /usr/local (or locally)
Create build directory and do ./configure
make, [ make check ], make install
Working directory: create SINDARIN steering file <input>.sin
Working directory: run whizard <input>.sin
Supported event formats: LHA, StdHep, LHEF (i-iii), HepMC, LCIO, div. ASCII
Interfaces to external packages: FastJet, GoSam, GuineaPig(++), HepMC, HOPPET, LCIO, LHAPDF(4/5/6), LoopTools, OpenLoops, PYTHIA6, [PYTHIA8], StdHep
![Page 73: The Event Generator WHIZARD for LC Top Physics - DESYreuter/downloads/LCTop2015.pdf · The Event Generator WHIZARD for LC Top Physics. J.R.Reuter WHIZARD for LC Top Physics LC Top](https://reader030.fdocuments.net/reader030/viewer/2022041223/5e0d88df4fc1b732724fe102/html5/thumbnails/73.jpg)
J.R.Reuter WHIZARD for LC Top Physics LC Top 2015, IFIC Valencia, 1.7.2015
Beams, Fields, Colors, Lorentz structures
Lorentz structures: Large number of hardcoded terms: pure scalar, pure vector, scalar/vector, fermion/scalar, fermion/vector, fermion/tensor, vector/tensor, gravitino couplings, fermion coupl. SUSY Ward id.Growing number of dim. 5/6/7/8 operators: HEFT, aTGCs, aQGCs, anomalous top couplings etc. Completely general Lorentz structures: foreseen for major next release (incl. UFO support), v2.3.0
![Page 74: The Event Generator WHIZARD for LC Top Physics - DESYreuter/downloads/LCTop2015.pdf · The Event Generator WHIZARD for LC Top Physics. J.R.Reuter WHIZARD for LC Top Physics LC Top](https://reader030.fdocuments.net/reader030/viewer/2022041223/5e0d88df4fc1b732724fe102/html5/thumbnails/74.jpg)
J.R.Reuter WHIZARD for LC Top Physics LC Top 2015, IFIC Valencia, 1.7.2015
Beams, Fields, Colors, Lorentz structures
Lorentz structures: Large number of hardcoded terms: pure scalar, pure vector, scalar/vector, fermion/scalar, fermion/vector, fermion/tensor, vector/tensor, gravitino couplings, fermion coupl. SUSY Ward id.Growing number of dim. 5/6/7/8 operators: HEFT, aTGCs, aQGCs, anomalous top couplings etc. Completely general Lorentz structures: foreseen for major next release (incl. UFO support), v2.3.0
Color structures: Color flow formalism Stelzer/Willenbrock, 2003; Kilian/Ohl/JRR/Speckner, 2011
Fundamental, antifundamental and adjoint representations Inofficial version for color sextets and diquark couplingsGeneral color structures coming tied to general Lorentz structures
![Page 75: The Event Generator WHIZARD for LC Top Physics - DESYreuter/downloads/LCTop2015.pdf · The Event Generator WHIZARD for LC Top Physics. J.R.Reuter WHIZARD for LC Top Physics LC Top](https://reader030.fdocuments.net/reader030/viewer/2022041223/5e0d88df4fc1b732724fe102/html5/thumbnails/75.jpg)
J.R.Reuter WHIZARD for LC Top Physics LC Top 2015, IFIC Valencia, 1.7.2015
Beams, Fields, Colors, Lorentz structures
Lorentz structures: Large number of hardcoded terms: pure scalar, pure vector, scalar/vector, fermion/scalar, fermion/vector, fermion/tensor, vector/tensor, gravitino couplings, fermion coupl. SUSY Ward id.Growing number of dim. 5/6/7/8 operators: HEFT, aTGCs, aQGCs, anomalous top couplings etc. Completely general Lorentz structures: foreseen for major next release (incl. UFO support), v2.3.0
Color structures: Color flow formalism Stelzer/Willenbrock, 2003; Kilian/Ohl/JRR/Speckner, 2011
Fundamental, antifundamental and adjoint representations Inofficial version for color sextets and diquark couplingsGeneral color structures coming tied to general Lorentz structures
Beams: Lepton beam ISR Kuraev/Fadin, 2003; Skrzypek/Jadach, 1991
Lepton collider beams: CIRCE1/2, also photon beams (more later)PDFs: interface to LHAPDF v4/5/6; internal PDFs: CTEQ6, CT10, MMHT
etc.
QCD parton shower: 2 own implementations [or ext., more later]
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J.R.Reuter WHIZARD for LC Top Physics LC Top 2015, IFIC Valencia, 1.7.2015
Phase Space SetupWHIZARD algorithm: heuristics to classify phase-space topology, adaptive multi-channel
mapping ⟹ resonant, t-channel, radiation, infrared, collinear, off-shell
Complicated processes: factorization into production and decay with the unstable option