Post on 30-Aug-2020
Amsterdam, 23 Nov 2012 Fabio Maltoni
“IS IT THE HIGGS?”
Amsterdam, annual HEP theory seminar 23 Nov 2012
Fabio MaltoniCentre for Cosmology,Particle Physics and Phenomenology (CP3)
NEW MC TOOLS FOR NEW CHALLENGES AT THE LHC
Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
wei
ghts
/ 2
GeV
20
40
60
80
100
H
Data S/B WeightedSig+Bkg Fit
Bkg (4th order polynomial)
ATLAS
-1Ldt=4.8fb=7 TeV, s-1Ldt=5.9fb=8 TeV, s
=126.5 GeV)H
(m
[GeV]m100 110 120 130 140 150 160
wei
ghts
- Bk
g
-8-4048
INDEPENDENCE DAY 2012
Clear evidence for a new bosonic resonance!Now reaching 7 σ
2Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
EXCITING HIGGS
3
C. Grojean® (adapted)
Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
EXCITING HIGGS
• 102 papers per year in the last 5 years starting with “the (main) goal of the LHC is to discover the Higgs boson and elucidate the mechanism of EWSB..”
3
C. Grojean® (adapted)
Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
EXCITING HIGGS
• 102 papers per year in the last 5 years starting with “the (main) goal of the LHC is to discover the Higgs boson and elucidate the mechanism of EWSB..”
• 104 papers with Higgs in the title
3
C. Grojean® (adapted)
Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
EXCITING HIGGS
• 102 papers per year in the last 5 years starting with “the (main) goal of the LHC is to discover the Higgs boson and elucidate the mechanism of EWSB..”
• 104 papers with Higgs in the title
• 107 hits on Google
3
C. Grojean® (adapted)
Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
EXCITING HIGGS
• 102 papers per year in the last 5 years starting with “the (main) goal of the LHC is to discover the Higgs boson and elucidate the mechanism of EWSB..”
• 104 papers with Higgs in the title
• 107 hits on Google
• Nobel prize...not yet!
3
C. Grojean® (adapted)
Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
EXCITING HIGGS
• 102 papers per year in the last 5 years starting with “the (main) goal of the LHC is to discover the Higgs boson and elucidate the mechanism of EWSB..”
• 104 papers with Higgs in the title
• 107 hits on Google
• Nobel prize...not yet!
WHY?
3
C. Grojean® (adapted)
Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
th
exp
REASONS FOR EXCITEMENT
4
C. Grojean® (adapted)
Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
• The last missing piece of the SM
th
exp
REASONS FOR EXCITEMENT
4
C. Grojean® (adapted)
Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
• The last missing piece of the SM
0 100 2000 100 200
level of excitement
th
exp
REASONS FOR EXCITEMENT
4
C. Grojean® (adapted)
Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
• The last missing piece of the SM
0 100 2000 100 200
level of excitement
th
exp
REASONS FOR EXCITEMENT
4
C. Grojean® (adapted)
Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
• The last missing piece of the SM
• At the origin of mass
0 100 2000 100 200
level of excitement
th
exp
REASONS FOR EXCITEMENT
4
C. Grojean® (adapted)
Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
• The last missing piece of the SM
• At the origin of mass
0 100 2000 100 200
level of excitement
th
exp
REASONS FOR EXCITEMENT
4
C. Grojean® (adapted)
Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
• The last missing piece of the SM
• At the origin of mass
• Unitarization of WW scattering
0 100 2000 100 200
level of excitement
th
exp
REASONS FOR EXCITEMENT
4
C. Grojean® (adapted)
Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
• The last missing piece of the SM
• At the origin of mass
• Unitarization of WW scattering
0 100 2000 100 200
level of excitement
th
exp
REASONS FOR EXCITEMENT
4
C. Grojean® (adapted)
Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
• The last missing piece of the SM
• At the origin of mass
• Unitarization of WW scattering
• An elementary scalar particle
0 100 2000 100 200
level of excitement
th
exp
REASONS FOR EXCITEMENT
4
C. Grojean® (adapted)
Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
• The last missing piece of the SM
• At the origin of mass
• Unitarization of WW scattering
• An elementary scalar particle
0 100 2000 100 200
level of excitement
th
exp
REASONS FOR EXCITEMENT
4
C. Grojean® (adapted)
Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
• The last missing piece of the SM
• At the origin of mass
• Unitarization of WW scattering
• An elementary scalar particle
• The carrier of a new interaction not under the spell of the gauge principle
0 100 200
not under the spell of the gauge principle
0 100 200
level of excitement
th
exp
REASONS FOR EXCITEMENT
4
C. Grojean® (adapted)
Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
• The last missing piece of the SM
• At the origin of mass
• Unitarization of WW scattering
• An elementary scalar particle
• The carrier of a new interaction not under the spell of the gauge principle
0 100 200
not under the spell of the gauge principle
0 100 200
level of excitement
th
exp
REASONS FOR EXCITEMENT
4
C. Grojean® (adapted)
Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
• The last missing piece of the SM
• At the origin of mass
• Unitarization of WW scattering
• An elementary scalar particle
• The carrier of a new interaction not under the spell of the gauge principle
• It was very difficult!
0 100 200
not under the spell of the gauge principle
0 100 200
level of excitement
th
exp
REASONS FOR EXCITEMENT
4
C. Grojean® (adapted)
Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
• The last missing piece of the SM
• At the origin of mass
• Unitarization of WW scattering
• An elementary scalar particle
• The carrier of a new interaction not under the spell of the gauge principle
• It was very difficult!
0 100 200
not under the spell of the gauge principle
0 100 200
level of excitement
th
exp
REASONS FOR EXCITEMENT
4
C. Grojean® (adapted)
Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
N = L · σ ·Br(H → visible)
HOW DIFFICULT?
5Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
Number of events
Luminosity Cross section Branching ratio
N = L · σ ·Br(H → visible)
HOW DIFFICULT?
5Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
Statistics⇒Exps⇒Discovery
Number of events
Luminosity Cross section Branching ratio
N = L · σ ·Br(H → visible)
HOW DIFFICULT?
5Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
Engineers⇒accelerator
Statistics⇒Exps⇒Discovery
Number of events
Luminosity Cross section Branching ratio
N = L · σ ·Br(H → visible)
HOW DIFFICULT?
5Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
Physics ⇒Theorists⇒ |Ψ|2
Engineers⇒accelerator
Statistics⇒Exps⇒Discovery
Number of events
Luminosity Cross section Branching ratio
N = L · σ ·Br(H → visible)
HOW DIFFICULT?
5Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
Interesting signals are rare:
HOW DIFFICULT?
6Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
Interesting signals are rare:
HOW DIFFICULT?
6Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
Interesting signals are rare:
LHC physics = QCD + !
HOW DIFFICULT?
6Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
Interesting signals are rare:
LHC physics = QCD + !
Find processes/strategies/techniques to get rid of the backgrounds!
HOW DIFFICULT?
6Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
Interesting signals are rare:
LHC physics = QCD + !
Find processes/strategies/techniques to get rid of the backgrounds!
HOW DIFFICULT?
Find processes/strategies/techniques to get rid of the backgrounds!
Advanced analyses techniques are needed that maximally exploit Advanced analyses techniques are needed that maximally exploit Advanced analyses techniques are needed that maximally exploit all distinctive features of signals vs backgrounds. Fully exclusive all distinctive features of signals vs backgrounds. Fully exclusive all distinctive features of signals vs backgrounds. Fully exclusive all distinctive features of signals vs backgrounds. Fully exclusive simulations of complex final states are necessary.simulations of complex final states are necessary.simulations of complex final states are necessary.simulations of complex final states are necessary.simulations of complex final states are necessary.
①
6Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
IS IT THE HIGGS?
The Higgs is certainly the most exotic particle of the SM, yet its properties are uniquely defined by its spin, mass and the other known parameters of the SM.
Property H X
Electric charge/color 0 0
Spin 0 0, 1, 2
Coupling strength mV,f,H κV,f,H· mV,f,H
Coupling structure LSM LSM+EFT
7Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
HIGGS RATES
Ht, b
g
g
H
q
q
W, Z
W, Z
H
g
g
Q
Q̄Hq̄
q
W, Z
W, Z
σ ·Br = σSM(ii → H) · ΓSM (H → ff, V V )
ΓSM (H)· κ2
Fκ2V/κ
2H
8Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
)�Signal strength ( -1 0 +1
Combined
4l (*) ZZH
H
l l (*) WWH
H
bbW,Z H
-1Ldt = 4.6 - 4.8 fb = 7 TeV: s-1Ldt = 5.8 - 13 fb = 8 TeV: s
-1Ldt = 4.8 fb = 7 TeV: s-1Ldt = 5.8 fb = 8 TeV: s
-1Ldt = 4.8 fb = 7 TeV: s-1Ldt = 5.9 fb = 8 TeV: s
-1Ldt = 13 fb = 8 TeV: s
-1Ldt = 4.6 fb = 7 TeV: s-1Ldt = 13 fb = 8 TeV: s
-1Ldt = 4.7 fb = 7 TeV: s-1Ldt = 13 fb = 8 TeV: s
= 126 GeVHm
0.3� = 1.3 �
ATLAS Preliminary
SM/Best fit -2 0 2 4
ZZH
WW (VH tag)H
WW (VBF tag)H
WW (0/1 jet)H
(VBF tag) H
(untagged) H
(VH tag) H
(VBF tag) H
(0/1 jet) H
bb (ttH tag)H
bb (VH tag)H
-1 12.2 fb = 8 TeV, L s -1 5.1 fb = 7 TeV, L s
CMS Preliminary = 125.8 GeVH m
HIGGS RATES:CHANNEL BY CHANNEL INFORMATION
9Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
V
0.4 0.6 0.8 1 1.2 1.4 1.6 1.8F
-2
-1
0
1
2
3
4 SMBest fit
) < 2.3F,V
(-2 ln ) < 6.0F,
V(-2 ln
-1Ldt = 5.8-5.9 fb = 8TeV, s
-1Ldt = 4.8 fb = 7TeV, sATLAS Preliminary
HIGGS COUPLING STRENGTHS
10Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
V
0.4 0.6 0.8 1 1.2 1.4 1.6 1.8F
-2
-1
0
1
2
3
4 SMBest fit
) < 2.3F,V
(-2 ln ) < 6.0F,
V(-2 ln
-1Ldt = 5.8-5.9 fb = 8TeV, s
-1Ldt = 4.8 fb = 7TeV, sATLAS Preliminary
HIGGS COUPLING STRENGTHS
-1
2
) < 6.0) < 6.0F,VV
(
Total and differential rates need to be accurate enough on all Total and differential rates need to be accurate enough on all Total and differential rates need to be accurate enough on all Total and differential rates need to be accurate enough on all Total and differential rates need to be accurate enough on all Total and differential rates need to be accurate enough on all 1Total and differential rates need to be accurate enough on all 1Total and differential rates need to be accurate enough on all Total and differential rates need to be accurate enough on all Total and differential rates need to be accurate enough on all Total and differential rates need to be accurate enough on all possible channels (production and decays) for signals as well as possible channels (production and decays) for signals as well as possible channels (production and decays) for signals as well as possible channels (production and decays) for signals as well as possible channels (production and decays) for signals as well as 0possible channels (production and decays) for signals as well as 0possible channels (production and decays) for signals as well as possible channels (production and decays) for signals as well as possible channels (production and decays) for signals as well as for QCD backgrounds.
②
10Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
SPIN HYPOTHESIS
LA =1
2gAG
aµνG̃
µν,aΦA
Lh = −1
4ghG
aµνG
µν,aΦ
LG = − 1
ΛTµνT µν
LV = ψ̄(a+ bγ5)γµψ V µ + Int(Vµ,W
+ν ,W−
ρ ) + Int(Vµ, Zν , Zρ)
0+
0-
1-/+
2+
Predictions need to be usable directly by experimentalists to make simulations
11Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
SPIN HYPOTHESIS
12Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
COUPLING STRUCTURES
Build an effective field theory LSM+EFT by adding dim=6 operators to the SM and imposing the symmetries of the SM. This theory is renormalizable order by order in 1/Λ, it p r o v i d e s a c o n s i s t e n t framework where to perform accurate predictions.
Approach superior to the usual “anomalous coupling” one.
13
[Contino, Grojean, Moretti, Piccinini, and Rattazzi, 2010]
Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
COUPLING STRUCTURES
Build an effective field theory LSM+EFT by adding dim=6 operators to the SM and imposing the symmetries of the SM. This theory is renormalizable order by order in 1/Λ, it p r o v i d e s a c o n s i s t e n t framework where to perform accurate predictions.
Approach superior to the usual “anomalous coupling” one.
Build an effective field theory L by adding dim=6 operators to the SM and imposing the symmetries of the SM.
Possibility of having predictions of the same level of accuracy of Possibility of having predictions of the same level of accuracy of LPossibility of having predictions of the same level of accuracy of LSM+EFTPossibility of having predictions of the same level of accuracy of SM+EFT by adding dim=6 Possibility of having predictions of the same level of accuracy of by adding dim=6 SM+EFT by adding dim=6 SM+EFTPossibility of having predictions of the same level of accuracy of SM+EFT by adding dim=6 SM+EFT
operators to the SM and Possibility of having predictions of the same level of accuracy of
operators to the SM and the SM for SIMPLE extensions (Resonant or EFT) of the the SM for SIMPLE extensions (Resonant or EFT) of the operators to the SM and the SM for SIMPLE extensions (Resonant or EFT) of the operators to the SM and imposing the symmetries of the
the SM for SIMPLE extensions (Resonant or EFT) of the imposing the symmetries of the
standard model states, in an easy, reliable and flexible way. standard model states, in an easy, reliable and flexible way. imposing the symmetries of the
standard model states, in an easy, reliable and flexible way. imposing the symmetries of the SM. standard model states, in an easy, reliable and flexible way. SM.
③
13
[Contino, Grojean, Moretti, Piccinini, and Rattazzi, 2010]
Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
COUPLING STRUCTURES
Build an effective field theory LSM+EFT by adding dim=6 operators to the SM and imposing the symmetries of the SM. This theory is renormalizable order by order in 1/Λ, it p r o v i d e s a c o n s i s t e n t framework where to perform accurate predictions.
Approach superior to the usual “anomalous coupling” one.
Build an effective field theory L by adding dim=6 operators to the SM and imposing the symmetries of the SM.
Possibility of having predictions of the same level of accuracy of Possibility of having predictions of the same level of accuracy of LPossibility of having predictions of the same level of accuracy of LSM+EFTPossibility of having predictions of the same level of accuracy of SM+EFT by adding dim=6 Possibility of having predictions of the same level of accuracy of by adding dim=6 SM+EFT by adding dim=6 SM+EFTPossibility of having predictions of the same level of accuracy of SM+EFT by adding dim=6 SM+EFT
operators to the SM and Possibility of having predictions of the same level of accuracy of
operators to the SM and the SM for SIMPLE extensions (Resonant or EFT) of the the SM for SIMPLE extensions (Resonant or EFT) of the operators to the SM and the SM for SIMPLE extensions (Resonant or EFT) of the operators to the SM and imposing the symmetries of the
the SM for SIMPLE extensions (Resonant or EFT) of the imposing the symmetries of the
standard model states, in an easy, reliable and flexible way. standard model states, in an easy, reliable and flexible way. imposing the symmetries of the
standard model states, in an easy, reliable and flexible way. imposing the symmetries of the SM. standard model states, in an easy, reliable and flexible way. SM.
③
framework where to perform accurate predictions.
Approach superior to the usual “anomalous coupling” one.
Possibility of having accurate predictions for COMPLETE Possibility of having accurate predictions for COMPLETE Approach superior to the usual Possibility of having accurate predictions for COMPLETE Approach superior to the usual MODELS beyond the SM, in an easy, reliable and flexible way. MODELS beyond the SM, in an easy, reliable and flexible way.
Approach superior to the usual MODELS beyond the SM, in an easy, reliable and flexible way.
Approach superior to the usual “anomalous coupling” one.MODELS beyond the SM, in an easy, reliable and flexible way. “anomalous coupling” one.
④
13
[Contino, Grojean, Moretti, Piccinini, and Rattazzi, 2010]
Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
Idea
TH
Aut. Feyn. Rules
Any amplitude
Any x-sec
partonic events
PHENO
Lagrangian
Pythia
EXP
Detec. Sim.
Data
PGS
Pythia
Paper
Feyn. Rules
Amplitudes
x secs
Paper
New MC
Paper
New Pythia
Amps 2→2
BSM TH/EXP INTERACTIONS : THE OLD WAY
14Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
• Workload is tripled!
• Long delays due to localized expertise and error prone. Painful validations are necessary at each step.
• Accurate predictions take a LONG time to be available.
• It leads to a proliferation of private MC tools/sample productions impossible to maintain, document and reproduce on the mid- and long- term.
• Just publications is a very inefficient way of communicating between TH/PHENO/EXP.
BSM TH/EXP INTERACTIONS : THE OLD WAY
15Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
• Workload is tripled!
• Long delays due to localized expertise and error prone. Painful validations are necessary at each step.
• Accurate predictions take a LONG time to be available.
• It leads to a proliferation of private MC tools/sample productions impossible to maintain, document and reproduce on the mid- and long- term.
• Just publications is a very inefficient way of communicating between TH/PHENO/EXP.
BSM TH/EXP INTERACTIONS : THE OLD WAY
• Accurate predictions take a LONG time to be available.
• It leads to a proliferation of private MC tools/sample
Streamline the TH/EXP interactions. Accurate predictions take a LONG time to be available.Streamline the TH/EXP interactions. Accurate predictions take a LONG time to be available.⑤
15Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
...SO HOW WE (USED TO) MAKE
PREDICTIONS AT HADRON COLLIDERS?
16Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
LHC master formula
17Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
p
LHC master formula
p
x1E x2E
�+ �−
17Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
p
LHC master formula
p
µFµF
x1E x2E
�+ �−
17Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
p
LHC master formula
! !̂ab!X(x1, x2, "S(µ2
R),Q2
µ2
F
,Q2
µ2
R
)!X =!a,b
" 1
0
dx1dx2 fa(x1, µ2
F )fb(x2, µ2
F )
p
µFµF
x1E x2E
�+ �−
17Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
p
LHC master formula
! !̂ab!X(x1, x2, "S(µ2
R),Q2
µ2
F
,Q2
µ2
R
)!X =!a,b
" 1
0
dx1dx2 fa(x1, µ2
F )fb(x2, µ2
F )
p
µFµF
x1E x2E
�+ �−
long distancelong distance
17Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
p
LHC master formula
! !̂ab!X(x1, x2, "S(µ2
R),Q2
µ2
F
,Q2
µ2
R
)!X =!a,b
" 1
0
dx1dx2 fa(x1, µ2
F )fb(x2, µ2
F )
p
µFµF
x1E x2E
�+ �−
long distancelong distance
Phenomenologists exploit this formula to provide accurate and flexible predictions from a given model (SM, MSSM,...)
17Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
• For low multiplicity include higher order terms in our fixed-order calculations (LO→NLO→NNLO...) ⇒
• For high multiplicity use the tree-level results
First way:
!̂ab!X = !0 + "S!1 + "2
S!2 + . . .
Comments:1. The theoretical errors systematically decrease.2. Pure theoretical point of view. 3. A lot of new techniques and universal algorithms have been developed. 4. Final description only in terms of partons and calculation of IR safe observables ⇒ not directly useful for simulations
TH
HOW WE (USED TO) MAKE PREDICTIONS?
18Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
NLO BASICS
NLO contributions have three parts
19Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
NLO BASICS
NLO contributions have three parts
Virtual part
σNLO =
�
md(d)σV +
19Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
NLO BASICS
NLO contributions have three parts
Virtual part
σNLO =
�
md(d)σV +
� �� �
Real emission part
�
m+1d(d)σR+
19Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
NLO BASICS
NLO contributions have three parts
Virtual part
σNLO =
�
md(d)σV +
� �� �
Real emission part
�
m+1d(d)σR+
�
md(4)σB
Born
19Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
NLO BASICS
NLO contributions have three parts
Virtual part
σNLO =
�
md(d)σV +
� �� �
Real emission part
�
m+1d(d)σR+
�
md(4)σB
Born
Loops have been for long the bottleneck of NLO computations
Virtuals and Reals are each divergent and subtraction scheme need to be used (Dipoles, FKS, Antenna’s)
A lot of work is necessary for each computation
19Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
NLO BASICS
NLO contributions have three parts
Virtual part
σNLO =
�
md(d)σV +
� �� �
Real emission part
�
m+1d(d)σR+
�
md(4)σB
Born
The cost of a new prediction at NLO can easily exceed 100k$.
Loops have been for long the bottleneck of NLO computations
Virtuals and Reals are each divergent and subtraction scheme need to be used (Dipoles, FKS, Antenna’s)
A lot of work is necessary for each computation
19Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
LOOP TECHNIQUES
modified by the speaker
20Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
BEST EXAMPLE: MCFM
Downloadable general purpose NLO code [Campbell, Ellis, Williams+collaborators]
☞ ~30 processes
☞ First results implemented in 1998 ...this is 13 years worth of work of several people (~5M $/€/CHF)☞ Cross sections and parton-level distributions at NLO are provided
☞ One general framework. However, each process implemented by hand
Final state Notes Reference
W/Z
diboson(W/Z/γ)
photon fragmentation, anomalous couplings
hep-ph/9905386,arXiv:1105.0020
Wbb massless b-quarkmassive b quark
hep-ph/9810489arXiv:1011.6647
Zbb massless b-quark hep-ph/0006304
W/Z+1 jet
W/Z+2 jetshep-ph/0202176,hep-ph/0308195
Wc massive c-quark hep-ph/0506289
Zb 5-flavour scheme hep-ph/0312024
Zb+jet 5-flavour scheme hep-ph/0510362
Final state Notes Reference
H (gluon fusion)
H+1 jet (g.f.) effective coupling
H+2 jets (g.f.) effective couplinghep-ph/0608194,arXiv:1001.4495
WH/ZH
H (WBF) hep-ph/0403194
Hb 5-flavour scheme hep-ph/0204093
ts- and t-channel (5F),top decay included
hep-ph/0408158
t t-channel (4F)arXiv:0903.0005,arXiv:0907.3933
Wt 5-flavour scheme hep-ph/0506289
top pairs top decay included
21Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
What about NNLO?
•Virtual-Virtual : O(100) terms
•Real-Virtual : O(300) terms
•Real-Real : O(500) terms
22Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
• Handful of parton-level results available mostly 2→1 at the Born level : Higgs, Drell-Yan, HV, VBF.
• Algorithms now available to deal any pp→color singlets at NNLO
• Bottleneck: numerical and local combination of all the various terms
• Several proposals not fully worked out yet for process independent algos..
What about NNLO?
+NNLO =
23Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
associated production with heavy quarks
Ht, b
g
g
H
q
q
W, Z
W, Z
H
g
g
Q
Q̄
Hq̄
q
W, Z
W, Z
GluonFusion
vector boson fusion (VBF)
associated production with vector bosons
Higgs predictions at 8 TeV
24Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
• Describe final states with high multiplicities starting from 2 →1 or 2 →2 procs, using parton showers, and then an hadronization model.
Second way:
EXP
Comments:
1. Fully exclusive final state description for detector simulations2. Normalization is very uncertain3. Very crude kinematic distributions for multi-parton final states 4. Improvements are only at the model level.
most known and used : PYTHIA, HERWIG, SHERPA
HOW WE (USED TO) MAKE PREDICTIONS?
25Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
SM STATUS A FEW YEARS AGO
pp→ n particles
26Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
SM STATUS A FEW YEARS AGO
pp→ n particles
complexity [n]1 32 54 6 87 9 10
26Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
SM STATUS A FEW YEARS AGO
pp→ n particles
complexity [n]1 32 54 6 87 9 10
accuracy [loops]
0
1
2
26Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
SM STATUS A FEW YEARS AGO
pp→ n particles
complexity [n]1 32 54 6 87 9 10
accuracy [loops]
0
1
2 fully exclusive
fully inclusive
parton-level
26Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
SM STATUS A FEW YEARS AGO
pp→ n particles
complexity [n]1 32 54 6 87 9 10
accuracy [loops]
0
1
2 fully exclusive
fully inclusive
parton-level
26Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
WHAT ABOUT NEW PHYSICS?
b
b~
χ01
χ02
b-
g
g~g~
g~
g
u-
~u
u
χ01
27Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
pp→ n particles
complexity [n]1 32 54 6 87 9 10
accuracy [loops]
0
1
2fully exclusive
fully inclusive
parton-level
BSM (=SUSY)STATUS A FEW YEARS AGO
28Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
DESIDERATA
29Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
DESIDERATA
Advanced analyses techniques are needed that maximally exploit all distinctive features of signals vs backgrounds. Fully exclusive simulations of complex final states are necessary.
Total and differential rates need to be accurate enough on all possible channels (production and decays) for signals as well as for QCD backgrounds.
Possibility of having accurate predictions for COMPLETE MODELS beyond the SM, in an easy, reliable and flexible way.
Possibility of having predictions of the same level of accuracy of the SM for SIMPLE extensions (Resonant or EFT) of the standard model states, in an easy, reliable and flexible way.
①
②
③
④
⑤29
Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
DESIDERATA
Advanced analyses techniques are needed that maximally exploit all distinctive features of signals vs backgrounds. Fully exclusive simulations of complex final states are necessary.
Total and differential rates need to be accurate enough on all possible channels (production and decays) for signals as well as for QCD backgrounds.
Possibility of having accurate predictions for COMPLETE MODELS beyond the SM, in an easy, reliable and flexible way.
Possibility of having predictions of the same level of accuracy of the SM for SIMPLE extensions (Resonant or EFT) of the standard model states, in an easy, reliable and flexible way.
Streamline the TH/EXP interactions:Obtain directly usable predictions at the touch of a button (automation).
①
②
③
④
⑤29
Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
DESIDERATA
Advanced analyses techniques are needed that maximally exploit all distinctive features of signals vs backgrounds. Fully exclusive simulations of complex final states are necessary.
Total and differential rates need to be accurate enough on all possible channels (production and decays) for signals as well as for QCD backgrounds.
Possibility of having accurate predictions for COMPLETE MODELS beyond the SM, in an easy, reliable and flexible way.
Possibility of having predictions of the same level of accuracy of the SM for SIMPLE extensions (Resonant or EFT) of the standard model states, in an easy, reliable and flexible way.
Obtain directly usable predictions at the touch of a button (automation).
Advanced analyses techniques are needed that maximally exploit all distinctive features of signals vs backgrounds. Fully exclusive simulations of complex final states are necessary.
Total and differential rates need to be accurate enough on all possible channels (production and decays) for signals as well as for QCD backgrounds.
Possibility of having accurate predictions for COMPLETE MODELS beyond the SM, in an easy, reliable and flexible way.
Possibility of having predictions of the same level of accuracy of the SM for SIMPLE extensions (Resonant or EFT) of the standard model states, in an easy, reliable and flexible way.
Streamline the TH/EXP interactions:Obtain directly usable predictions at the touch of a button (automation).
①
②
③
④
⑤29
Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
MC (SIMPLIFIED) PROGRESS
2002
20112008 2009
2012
30Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
MC (SIMPLIFIED) PROGRESS
Merging at NLOMerging and
matching:ME+PS
NLOwPS
New Looptechniques
BSM framework
Fully Automatic NLOwPS
2002
20112008 2009
2012
30Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
PREDICTIVE MC’S
• There are various ways to improve a Parton Shower Monte Carlo event generator with matrix elements:
• ME+PS merging: Include matrix elements with more final state partons to describe hard, well-separated radiation better.
[M.L. Mangano, 2002]
[Catani, Krauss, Kuhn, Webber,2001]
31Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
Merging fixed order with PS
Parton
Mat
rix
...
...
...
...
kT < Qc
kT < Qc
kT < Qc
kT < Qc
kT > QckT > Qc
kT > Qc
kT > Qc
32Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
Merging fixed order with PS
Parton
Mat
rix
...
...
...
...
kT < Qc
kT < Qc
kT < Qc
kT < Qc
kT > QckT > Qc
kT > Qc
kT > Qc
32Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
Merging fixed order with PS
Parton
Mat
rix
...
...
...
...
kT < Qc
kT < Qc
kT < Qc
kT < Qc
kT > QckT > Qc
kT > Qc
kT > Qc
...
32Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
Merging fixed order with PS
Works amazingly well...!!! Mature. Available in public codes such as Alpgen, MadGraph and Sherpa.
Parton
Mat
rix
...
...
...
...
kT < Qc
kT < Qc
kT < Qc
kT < Qc
kT > QckT > Qc
kT > Qc
kT > Qc
...
32Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
PREDICTIVE MC’S
• There are various ways to improve a Parton Shower Monte Carlo event generator with matrix elements:
• ME+PS merging: Include matrix elements with more final state partons to describe hard, well-separated radiation better.
• NLO+PS matching: Include full NLO corrections to the matrix elements to reduce theoretical uncertainties in the matrix elements. The real-emission matrix elements will describe the hard radiation.
[M.L. Mangano, 2002]
[Catani, Krauss, Kuhn, Webber,2001]
[Frixione & Webber (2002)][Nason (2004)]
33Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
NLOwPS in a nutshell
This formula is valid both for both MC@NLO and POWHEG
dσNLO+PS = dΦBB̄s(ΦB)
�∆s(pmin
⊥ ) + dΦR|BRs(ΦR)
B(ΦB)∆s(pT (Φ))
�+ dΦRR
f (ΦR)
B̄s = B(ΦB) +
�V (ΦB) +
�dΦR|BR
s(ΦR|B)
�with
R(ΦR) = Rs(ΦR) +Rf (ΦR)
Full cross section (if F=1) at fixed Born kinematics
integrates to 1 (unitarity)
MC@NLO:
POWHEG:
Rs(Φ) = P (ΦR|B)B(ΦB) Needs exact mapping (ΦB,ΦR) →Φ
F=1 = Exponentiates the Real. It can be damped by hand.Rs(Φ) = FR(Φ) , Rf(Φ) = (1− F )R(Φ)
34Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
SM STATUS : SINCE 2007pp→ n particles
complexity [n]1 32 54 6 87 9 10
accuracy [loops]
0
1
2fully exclusive
fully inclusive
parton-level
35Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
SM STATUS : SINCE 2007pp→ n particles
complexity [n]1 32 54 6 87 9 10
accuracy [loops]
0
1
2fully exclusive
fully inclusive
parton-level
35Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
Cost saving
Programs are modular and computations based on elements that can be systematically and extensively checked. Trust can beeasily built.
Robustness
One framework for all. Available to everybody for an unlimited set of applications for all. Suitable to EXP collaboration.
Wide accessibility
Trade human time and expertise spent on computing one process at the time with time on physics and pheno.
AUTOMATION
36Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
pp→ n particles
complexity [n]1 32 54 6 87 9 10
accuracy [loops]
0
1
2
fully exclusive and automatic
fully exclusive
fully inclusive
parton-level
SM STATUS : SINCE 2007
37Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
2003
20112008 2009
Matching:ME+PS
NLOwPS
New Looptechniques
BSM framework
Fully Automatic NLOwPS
QCD AND MC (SIMPLIFIED) PROGRESS
38Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
For the calculation of one-loop matrix elements, several methods are now established :
•Generalized Unitarity (ex. BlackHat, Rocket,...)[Bern, Dixon, Dunbar, Kosower, hep-ph/9403226 + ....; Ellis, Giele, Kunszt 0708.2398, +Melnikov 0806.3467]
•Integrand Reduction (ex. CutTools, Samurai) [Ossola, Papadopolulos, Pittau, hep-ph/0609007; del Aguila, Pittau, hep-ph/0404120; Mastrolia, Ossola, Reiter, Tramontano, 1006.0710]
•Tensor Reduction (ex. Golem)[Passarino, Veltman, 1979; Denner, Dittmaier, hep-ph/0509141, Binoth, Guillet, Heinrivh, Pilon, Reiter 0810.0092]
NEW LOOP TECHNIQUES
39Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
GUINNESS WR NLO CALCULATIONS
W+4 jets tt+2jets[Berger et al., 1009.2338] [Bevilacqua et al., 1002.4009]
HELAC-PHEGAS + CutTools
Both based on unitarity methods and recursive relations for trees.
40Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
Slide from L. Dixon
41Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
Slide from L. Dixon
pp →W + 5 jets 2012 BlackHat+Sherpa
41Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
2003
20112008 2009
Matching:ME+PS
NLOwPS
New Looptechniques
BSM framework
Fully Automatic NLOwPS
QCD AND MC (SIMPLIFIED) PROGRESS
42Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
Idea
TH
Aut. Feyn. Rules
Any amplitude
Any x-sec
partonic events
PHENO
Lagrangian
Pythia
EXP
Detec. Sim.
Data
PGS
Pythia
Paper
Feyn. Rules
Amplitudes
x secs
Paper
New MC
Paper
New Pythia
Amps 2→2
BSM TH/EXP INTERACTIONS : THE OLD WAY
43Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
Idea
TH
Aut. Feyn. Rules
Any amplitude
Any x-sec
partonic events
PHENO
Lagrangian
Pythia
EXP
Detec. Sim.
Data
BSM TH/EXP INTERACTIONS : THE OLD WAY
43Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
Idea
Lagrangian
FeynRules
ME Generator
Signal & Bkg
Events
PS+Had
Detect. Sim.
Data
TH EXP
BSM TH/EXP INTERACTIONS : THE NEW PATH
Papers
44Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
Idea
Lagrangian
FeynRules
ME Generator
Signal & Bkg
Events
PS+Had
Detect. Sim.
Data
๏ One path for all ๏ Physics and software validations streamlined๏ Robust and efficient Th/Exp communication๏ It works top-down and bottom-up
TH EXP
BSM TH/EXP INTERACTIONS : THE NEW PATH
Papers
44Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
Idea
Lagrangian
FeynRules
ME Generator
Signal & Bkg
Events
PS+Had
Detect. Sim.
Data
๏ One path for all ๏ Physics and software validations streamlined๏ Robust and efficient Th/Exp communication๏ It works top-down and bottom-up
Complete automatization LO (and now NLO) calculations available, including merging with the parton shower in multi-jet final states, for SM as well as for BSM physics. Automatization of NLO is very promising now...
TH EXP
BSM TH/EXP INTERACTIONS : THE NEW PATH
Papers
44Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
Lagrangian
FeynArts
UFO
TeX Feynman Rules
Model-fileParticles, parameters, ...
FeynRules
Golem
MadGraph 5
Sherpa
[Christensen, Degrande, Duhr, Fuks]
Whizard
CalcHep
Whizard HERWIG
THE FEYNRULES PROJECT
45Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
THE FEYNRULES PROJECT
46Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
THE FEYNRULES PROJECT
46Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
X=JP with MadGraph5
LA =1
2gAG
aµνG̃
µν,aΦA
Lh = −1
4ghG
aµνG
µν,aΦ
LG = − 1
ΛTµνT µν
LV = ψ̄(a+ bγ5)γµψ V µ + Int(Vµ,W
+ν ,W−
ρ ) + Int(Vµ, Zν , Zρ)
0+
0-
1-/+
2+
Any other state/interaction comes from higher-dimensional operators and it is therefore suppressed. For all the above interactions production and decay, (possibly including interference with SM processes), can be inherited by FeynRules and then simulated in MadGraph5 as inclusive merged samples for any production channel (which works out of the box).
[De Aquino et al. for HC2012]
47Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
[De Aquino et al. for HC2012]
You can now plot all you are interested in for production....
X=JP with MadGraph5
as well as spin correlated decays.
48Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
2003
20112008 2009
Matching:ME+PS
NLOwPS
New Looptechniques
BSM framework
Fully Automatic NLOwPS
QCD AND MC (SIMPLIFIED) PROGRESS
49Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
aMC@NLO [Alwall, Hirschi, Frederix, Frixione, FM, Mattelaer, Pittau, Torrielli, Zaro]
50Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
MadGraph5
aMC@NLO
Modular structure in the MadGraph5 framework:
[Alwall, Hirschi, Frederix, Frixione, FM, Mattelaer, Pittau, Torrielli, Zaro]
50Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
MadGraph5
aMC@NLO
Modular structure in the MadGraph5 framework:
• MadLoop (w/ Cuttools)
• MadFKS for subtractions
• MC@NLO counterterms for Pythia6Q2, Herwig, HW++. (Pythia8 validation on-going).
[Alwall, Hirschi, Frederix, Frixione, FM, Mattelaer, Pittau, Torrielli, Zaro]
MadFKS MadLoop
MC@NLO
50Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
MadGraph5
aMC@NLO
Modular structure in the MadGraph5 framework:
• MadLoop (w/ Cuttools)
• MadFKS for subtractions
• MC@NLO counterterms for Pythia6Q2, Herwig, HW++. (Pythia8 validation on-going).
[Alwall, Hirschi, Frederix, Frixione, FM, Mattelaer, Pittau, Torrielli, Zaro]
MadFKS MadLoop
MC@NLO
MadFKS MadLoop
MC@NLOMC@NLOMC@NLOMC@NLO
aMC@NLO
50Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
aMC@NLO possibilitiesThe range of SM processes that can be generated aMC@NLO (SM plus weak BSM) is only limited by computing power. It basically encompasses (and goes beyond) the current MCFM and POWHEG-Box libraries.
51Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
aMC@NLO possibilitiesThe range of SM processes that can be generated aMC@NLO (SM plus weak BSM) is only limited by computing power. It basically encompasses (and goes beyond) the current MCFM and POWHEG-Box libraries.
51Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
aMC@NLO possibilitiesThe range of SM processes that can be generated aMC@NLO (SM plus weak BSM) is only limited by computing power. It basically encompasses (and goes beyond) the current MCFM and POWHEG-Box libraries.
51Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
aMC@NLO possibilities
• Signal simulation in the SM:
• Automatic : e.g., pp→VBF, WH(+j),ZH(+j),ttH,...
• Available : pp→H +0,1,2 extra jets + FxFx (NLO) merging.
• Bkg simulation:
• Automatic : e.g., pp→tt, tj, V V, V V V, Vbb, V, Vj, Vjj, ttV,....
• Available: QCD rich final states.
• Higgs characterization pp→X(JP)+jets: codes publicly available.
• Extended Higgs sectors straightforward (in progress).
The range of SM processes that can be generated aMC@NLO (SM plus weak BSM) is only limited by computing power. It basically encompasses (and goes beyond) the current MCFM and POWHEG-Box libraries.
51Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
For H, NLO results known (but no public code available) for scalar Higgs since some time. No results for pseudoscalar A were known.
First fully automatic results for both H and A.
Experimental grade distributions for decaying tops and Higgs can be plotted.Spin correlated decays included via MadSpin.Combinatorics very hard to manage, is improved in the boosted case.
ttH/ttA (Z/W→ll/lv)bb VV→4l
aMC@NLO applications to Higgs physics
[aMC@NLO:1104.5613]
52Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
Extremely interesting QCD laboratory and background to the Higgs searches. H i s to r i c a l l y source o f TH/EXP discrepancies at Tevatron and now at the LHC. Topological difference between Z and W.
Very different mbb distributions. Full simulation for signal and background at NLOwPS!!
ttH/ttA (Z/W→ll/lv)bb VV→4l
aMC@NLO applications to Higgs physics
[aMC@NLO: 1106.6019]
53Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
Several NLO and NLO+PS results available (Herwig++ and POWHEG-BOX).
NLO calculation includes γ*/Z interference, full spin correlations and single resonant diagrams + one-loop gg channel.
First fully automatic NLO+PS results including automatic theoretical uncertainty band
aMC@NLO applications to Higgs physics
ttH/ttA (Z/W→ll/lv)bb VV→4l [aMC@NLO: 1110.4738].
54Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
a for automation LHC
EXP
55Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
a for automation
./bin/mg5> generate p p > H H j j, Gr > W+ W- [QCD]> output HHvbf> launch
or in studying spin-2 production in association with a W:
Suppose now you are interested in studying HH production in VBF:
LHC
EXP
55Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
a for automation
./bin/mg5> generate p p > H H j j, Gr > W+ W- [QCD]> output HHvbf> launch
or in studying spin-2 production in association with a W:
Suppose now you are interested in studying HH production in VBF:
> import model RS > generate p p > Gr Z, Gr > b b~ [QCD]> output vbf_gr> launch
LHC
EXP
55Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
a for automation
./bin/mg5> generate p p > H H j j, Gr > W+ W- [QCD]> output HHvbf> launch
or in studying spin-2 production in association with a W:
The range of SM processes that can be generated aMC@NLO (SM plus weak BSM) is only limited by computing power so it improves with time. It already encompasses and goes beyond the currently public tools based on libraries (MCFM, POWHEG-BOX,..)
Suppose now you are interested in studying HH production in VBF:
> import model RS > generate p p > Gr Z, Gr > b b~ [QCD]> output vbf_gr> launch
LHC
EXP
55Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
X=JP with aMC@NLO
LA =1
2gAG
aµνG̃
µν,aΦA
Lh = −1
4ghG
aµνG
µν,aΦ
LG = − 1
ΛTµνT µν
LV = ψ̄(a+ bγ5)γµψ V µ + Int(Vµ,W
+ν ,W−
ρ ) + Int(Vµ, Zν , Zρ)
0+
0-
1-/+
2+
These models can be upgraded to NLO easily (on-going). In the meantime using the known results for the finite part of the virtuals, one can simulate the production easily at NLO.
56Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
1e-05
0.0001
0.001
0.01
0.1
1
0 50 100 150 200 250 300 350 400
d/d
(PT
1 (G
eV))
(1/
TO
T) (p
b/bi
n)
PT 1 (GeV)
aMC@NLO X KT-MLM: p p > X > (+ 0, 1, 2 partons)
MG5 KT-MLM 0+MG5 KT-MLM 2+aMC @ NLO 0+aMC @ NLO 2+
Quite different spectra between spin 0 and spin 2 hypothesis. Very consistent pT shapes between ME+PS merging and aMC@NLO.
Is it the higgs?
57Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
SM STATUS : YEAR 2012pp→ n particles
complexity [n]1 32 54 6 87 9 10
accuracy [loops]
0
1
2 fully exclusive and automatic
fully exclusive
fully inclusive
parton-level
58Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
SM STATUS : YEAR 2012pp→ n particles
complexity [n]1 32 54 6 87 9 10
accuracy [loops]
0
1
2 fully exclusive and automatic
fully exclusive
fully inclusive
parton-level
aMC@NLO
58Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
CONCLUSIONS
59Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
CONCLUSIONS
✦ The need for better description and more reliable predictions for SM processes for the LHC has motivated a significant increase of theoretical and phenomenological activity in the last years, leading to several important achievements.
59Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
CONCLUSIONS
✦ The need for better description and more reliable predictions for SM processes for the LHC has motivated a significant increase of theoretical and phenomenological activity in the last years, leading to several important achievements.
✦ A new generation of tools and techniques is now available. Full Automation
of Accurate (NLO) computations at fixed order as well as their the matching to parton-shower has been proven for the SM. The frontier is now at NNLO.
59Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
CONCLUSIONS
✦ The need for better description and more reliable predictions for SM processes for the LHC has motivated a significant increase of theoretical and phenomenological activity in the last years, leading to several important achievements.
✦ A new generation of tools and techniques is now available. Full Automation
of Accurate (NLO) computations at fixed order as well as their the matching to parton-shower has been proven for the SM. The frontier is now at NNLO.
✦ Amazingly efficient, flexible and robust BSM simulation chain available and being continuously improved. Same level of sophistication as SM processes can be attained. Both top-down and bottom-up approaches included.
59Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
CONCLUSIONS
✦ The need for better description and more reliable predictions for SM processes for the LHC has motivated a significant increase of theoretical and phenomenological activity in the last years, leading to several important achievements.
✦ A new generation of tools and techniques is now available. Full Automation
of Accurate (NLO) computations at fixed order as well as their the matching to parton-shower has been proven for the SM. The frontier is now at NNLO.
✦ Amazingly efficient, flexible and robust BSM simulation chain available and being continuously improved. Same level of sophistication as SM processes can be attained. Both top-down and bottom-up approaches included.
✦ EXP/TH interactions enhanced by a new framework and not limited anymore by the burden of heavy/long and inefficient calculations...
59Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni59Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
IS IT THE HIGGS?
60Tuesday 27 November 2012
Amsterdam, 23 Nov 2012 Fabio Maltoni
IS IT THE HIGGS?
60Tuesday 27 November 2012