“IS IT THE HIGGS?”...s=7 TeV, Ldt=4.8fb-1 s=8 TeV, Ldt=5.9fb-1 =126.5 GeV) H (m m [GeV] weights...

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


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


EXCITING HIGGS

3

C. Grojean® (adapted)



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




EXCITING HIGGS


• 104 papers with Higgs in the title

3




EXCITING HIGGS



• 107 hits on Google

3




EXCITING HIGGS




• Nobel prize...not yet!

3




EXCITING HIGGS




• Nobel prize...not yet!

WHY?

3




th

exp

REASONS FOR EXCITEMENT

4




• The last missing piece of the SM

th

exp


4





0 100 2000 100 200

level of excitement

th

exp


4





• At the origin of mass

0 100 2000 100 200

level of excitement

th

exp


4






• Unitarization of WW scattering

0 100 2000 100 200

level of excitement

th

exp


4







• An elementary scalar particle

0 100 2000 100 200

level of excitement

th

exp


4








• 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


4








• 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


4




N = L · σ ·Br(H → visible)

HOW DIFFICULT?



Number of events

Luminosity Cross section Branching ratio


HOW DIFFICULT?



Statistics⇒Exps⇒Discovery

Number of events



HOW DIFFICULT?



Engineers⇒accelerator


Number of events



HOW DIFFICULT?



Physics ⇒Theorists⇒ |Ψ|2

Engineers⇒accelerator


Number of events



HOW DIFFICULT?



Interesting signals are rare:

HOW DIFFICULT?




LHC physics = QCD + !

HOW DIFFICULT?





Find processes/strategies/techniques to get rid of the backgrounds!

HOW DIFFICULT?






HOW DIFFICULT?


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



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



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



)�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



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



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



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



SPIN HYPOTHESIS



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]



COUPLING STRUCTURES



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




COUPLING STRUCTURES



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.


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




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



• 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.




• Workload is tripled!

• Long delays due to localized expertise and error prone. Painful validations are necessary at each step.


• 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.



• 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



...SO HOW WE (USED TO) MAKE

PREDICTIONS AT HADRON COLLIDERS?



LHC master formula



p

LHC master formula

p

x1E x2E

�+ �−



p

LHC master formula

p

µFµF

x1E x2E

�+ �−



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

�+ �−



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



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,...)



• 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?



NLO BASICS

NLO contributions have three parts



NLO BASICS


Virtual part

σNLO =

�

md(d)σV +



NLO BASICS


Virtual part

σNLO =

�

md(d)σV +

� ��

Real emission part

�

m+1d(d)σR+



NLO BASICS


Virtual part

σNLO =

�

md(d)σV +

� ��

Real emission part

�

m+1d(d)σR+

�

md(4)σB

Born



NLO BASICS


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



NLO BASICS


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



LOOP TECHNIQUES

modified by the speaker



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



What about NNLO?

•Virtual-Virtual : O(100) terms

•Real-Virtual : O(300) terms

•Real-Real : O(500) terms



• 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 =



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



• 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?



SM STATUS A FEW YEARS AGO

pp→ n particles




pp→ n particles

complexity [n]1 32 54 6 87 9 10




pp→ n particles

complexity [n]1 32 54 6 87 9 10

accuracy [loops]

0

1

2




pp→ n particles

complexity [n]1 32 54 6 87 9 10

accuracy [loops]

0

1

2 fully exclusive

fully inclusive

parton-level



WHAT ABOUT NEW PHYSICS?

b

b~

χ01

χ02

b-

g

g~g~

g~

g

u-

~u

u

χ01



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



DESIDERATA



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



DESIDERATA





Streamline the TH/EXP interactions:Obtain directly usable predictions at the touch of a button (automation).

①

②

③

④

⑤29



DESIDERATA





Obtain directly usable predictions at the touch of a button (automation).





Streamline the TH/EXP interactions:Obtain directly usable predictions at the touch of a button (automation).

①

②

③

④

⑤29



MC (SIMPLIFIED) PROGRESS

2002

20112008 2009

2012



MC (SIMPLIFIED) PROGRESS

Merging at NLOMerging and

matching:ME+PS

NLOwPS

New Looptechniques

BSM framework

Fully Automatic NLOwPS

2002

20112008 2009

2012



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]



Merging fixed order with PS

Parton

Mat

rix

...

...

...

...

kT < Qc

kT < Qc

kT < Qc

kT < Qc

kT > QckT > Qc

kT > Qc

kT > Qc




Parton

Mat

rix

...

...

...

...

kT < Qc

kT < Qc

kT < Qc

kT < Qc

kT > QckT > Qc

kT > Qc

kT > Qc

...




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

...



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)]



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)



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



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



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



2003

20112008 2009

Matching:ME+PS

NLOwPS

New Looptechniques

BSM framework


QCD AND MC (SIMPLIFIED) PROGRESS



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



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.



Slide from L. Dixon



Slide from L. Dixon

pp →W + 5 jets 2012 BlackHat+Sherpa



2003

20112008 2009

Matching:ME+PS

NLOwPS

New Looptechniques

BSM framework





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




Idea

TH

Aut. Feyn. Rules

Any amplitude

Any x-sec

partonic events

PHENO

Lagrangian

Pythia

EXP

Detec. Sim.

Data




Idea

Lagrangian

FeynRules

ME Generator

Signal & Bkg

Events

PS+Had

Detect. Sim.

Data

TH EXP

BSM TH/EXP INTERACTIONS : THE NEW PATH

Papers



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


Papers



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


Papers



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



THE FEYNRULES PROJECT



X=JP with MadGraph5

LA =1

2gAG

aµνG̃

µν,aΦA

Lh = −1

4ghG

aµνG

µν,aΦ

LG = − 1

ΛTµνT µν


+ν ,W−


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]



[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.



2003

20112008 2009

Matching:ME+PS

NLOwPS

New Looptechniques

BSM framework





aMC@NLO [Alwall, Hirschi, Frederix, Frixione, FM, Mattelaer, Pittau, Torrielli, Zaro]



MadGraph5

aMC@NLO

Modular structure in the MadGraph5 framework:

[Alwall, Hirschi, Frederix, Frixione, FM, Mattelaer, Pittau, Torrielli, Zaro]



MadGraph5

aMC@NLO


• MadLoop (w/ Cuttools)

• MadFKS for subtractions

• MC@NLO counterterms for Pythia6Q2, Herwig, HW++. (Pythia8 validation on-going).


MadFKS MadLoop

MC@NLO



MadGraph5

aMC@NLO


• MadLoop (w/ Cuttools)

• MadFKS for subtractions

• MC@NLO counterterms for Pythia6Q2, Herwig, HW++. (Pythia8 validation on-going).


MadFKS MadLoop

MC@NLO

MadFKS MadLoop

MC@NLOMC@NLOMC@NLOMC@NLO

aMC@NLO



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.



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.



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]



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: 1106.6019]



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


ttH/ttA (Z/W→ll/lv)bb VV→4l [aMC@NLO: 1110.4738].



a for automation LHC

EXP



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



a for automation




> import model RS > generate p p > Gr Z, Gr > b b~ [QCD]> output vbf_gr> launch

LHC

EXP



a for automation



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,..)


> import model RS > generate p p > Gr Z, Gr > b b~ [QCD]> output vbf_gr> launch

LHC

EXP



X=JP with aMC@NLO

LA =1

2gAG

aµνG̃

µν,aΦA

Lh = −1

4ghG

aµνG

µν,aΦ

LG = − 1

ΛTµνT µν


+ν ,W−


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.



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?



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



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



CONCLUSIONS



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.



CONCLUSIONS


✦ 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.



CONCLUSIONS




✦ 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.



CONCLUSIONS




✦ 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...


Amsterdam, 23 Nov 2012 Fabio Maltoni59Tuesday 27 November 2012


IS IT THE HIGGS?


“IS IT THE HIGGS?”...s=7 TeV, Ldt=4.8fb-1 s=8 TeV, Ldt=5.9fb-1 =126.5 GeV) H (m m [GeV] weights...

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Transcript of “IS IT THE HIGGS?”...s=7 TeV, Ldt=4.8fb-1 s=8 TeV, Ldt=5.9fb-1 =126.5 GeV) H (m m [GeV] weights...