Challenges for EFTs at Run2 LHC Veronica Sanz (Sussex) HEFT2015, - - PowerPoint PPT Presentation

Challenges for EFTs at Run2 LHC

Veronica Sanz (Sussex)

HEFT2015, Chicago

Outline

EFTs: how do we look for New Physics with them Challenges for EFTs: precision and breakdown Precision: NLO QCD Breakdown: Benchmarks in extended Higgs sectors

Effective Field Theory

heavy New Physics

Advantages of EFT

model independent

• Systematic studies
• One operator, corrs.
• Translation to thy

New Physics could be heavy as compared with the typical energy of the channel we look at EFT: expansion in higher- dimensional operators (HDOs)

Buchmuller and Wyler. NPB (86)

Contino et al. 1303.3873

coupling HWW at dim-6

Expansion in inverse powers of NP scale dim6, dim8, …

here, assuming Higgs doublet non-linear: see talks by Merlo, Krause, Panico

How do we look for HDOs?

Rates and differential distributions

New Physics induces new coupling structures of SM particles, incl the Higgs Higgs anomalous couplings

−1 4h g(1)

hV V VµνV µν

−h g(2)

hV V Vν∂µV µν

−1 4h ˜ ghV V Vµν ˜ V µν

h(p1)

V (p2) V (p3)

iηµν ✓ g(1)

hV V

✓ ˆ s 2 − m2

V

◆ + 2g(2)

hV V m2 V

◆

−i˜ ghV V ✏µναβp2,αp3,β −ig(1)

hV V pµ 3pν 2

HDOs generate HVV interactions with more derivatives

• ex. Feynman rule if mh>2mV

Higgs anomalous couplings

−1 4h g(1)

hV V VµνV µν

−h g(2)

hV V Vν∂µV µν

−1 4h ˜ ghV V Vµν ˜ V µν

h(p1)

V (p2) V (p3)

iηµν ✓ g(1)

hV V

✓ ˆ s 2 − m2

V

◆ + 2g(2)

hV V m2 V

◆

−i˜ ghV V ✏µναβp2,αp3,β −ig(1)

hV V pµ 3pν 2

HDOs generate HVV interactions with more derivatives

• ex. Feynman rule if mh>2mV

New Physics induces new coupling structures of SM particles, incl the Higgs Higgs anomalous couplings h(p1)

V (p2) V (p3)

iηµν ✓ g(1)

hV V

✓ ˆ s 2 − m2

V

◆ + 2g(2)

hV V m2 V

◆

−i˜ ghV V ✏µναβp2,αp3,β −ig(1)

hV V pµ 3pν 2

Higgs anomalous couplings h(p1)

V (p2) V (p3)

iηµν ✓ g(1)

hV V

✓ ˆ s 2 − m2

V

◆ + 2g(2)

hV V m2 V

◆

−i˜ ghV V ✏µναβp2,αp3,β −ig(1)

hV V pµ 3pν 2

Changes in total rates and differential information

Anomalous couplings vs EFT coefficients

Gorbahn, No, VS. 1502.07352

Differential information: channels which probe a large kinematic regime e.g. VH and H+j

q

q0

V ∗

V

h

ATLAS-CONF-2013-079

LHC8

Feynrules -> MG5-> pythia->Delphes3

verified for SM/BGs => expectation for EFT

ATLAS-CONF-2013-079

LHC8

50 100 150 200 250 2 4 6 8 10 12 pT HGeVL Nev LHC8 ATLAS VH

simulation

¯ cW = 0.1

¯ cW = 0.05

SM inclusive cross section is less sensitive than distribution

• Ellis, VS and You. 1404.3667, 1410.7703

cW

Global fit

• ne-by-one

global stronger in classes of models e.g. extended Higgs sectors

global

• Gorbahn, No, VS. 1502.07352
• Ellis, VS and You. 1410.7703

Run1 constraints

How bad is it?

Challenges for EFTs at Run2

Best sensitivity to new physics exploiting differential information

50 100 150 200 250 2 4 6 8 10 12 pT HGeVL Nev LHC8 ATLAS VH

¯ cW = 0.1

¯ cW = 0.05

SM most sensitive bin:

• verflow (last) bin

At high-pT sensitive to dynamics of new physics breakdown of EFT To what extent can we use this bin? how far does it extend?

Challenges of looking at tails of distributions

Generally speaking

1 2

Precise determination Higher-order SM and EFT under control Range of validity Need of benchmarks

Precision, precision

Differential distributions

depend on cuts need radiation and detector effects

Simulation tools

Leff = X

i

fi Λ2 Oi

Collider simulation theory

• bservables

Limit coefficients = new physics

Better theory calculations, but also inclusion in a MC generator

example: NLO QCD in VH

10−3 10−2 10−1

d dMVH [fb/ 25 GeV]

Higgs-Z invariant mass (pp → H Z → b ¯ b `+`−) SM POWHEG+PYTHIA8 MCFM NLO MCFM LO POWHEG+PYTHIA8 MCFM NLO MCFM LO 150 200 250 300 350 400 450

MVH [GeV]

−60 −30 30 60

(%)

• Mimasu, VS, Williams. in prep

LO vs NLO, showering effects

example: NLO QCD in VH

• Mimasu, VS, Williams. in prep

10−3 10−2 10−1

d dMVH [fb/ 25 GeV]

Higgs-Z invariant mass (pp → H Z → b ¯ b `+`−) SM (q ¯ q + gg) cW = −0.02 cHW = 0.015 SM (q ¯ q + gg) cW = −0.02 cHW = 0.015 150 200 250 300 350 400 450

MVH [GeV]

−100 −50 50 100

BSM(%)

NLO QCD POWHEG+PYTHIA8

alternative tool in aMC@NLO

deGrande, Fuks, Mawatari, Mimasu, VS. in prep

Matching UV completions to the EFT

• Gorbahn, No, VS. 1502.07352

recent paper by Brehmer, Freitas, Lopez-Val , Phlehn. 1510.03443

Need benchmarks to test the validity

• f the approach

Where/how does the EFT break down? depends on UV completion

50 100 150 200 250 2 4 6 8 10 12 pT HGeVL Nev LHC8 ATLAS VH

¯ cW = 0.1

¯ cW = 0.05

Breakdown depends on loop-induced or tree-level

Gorbahn, No, VS. 1502.07352

1. Tree-level mixing: Higgs+Singlet 2. Loop-induced EFT: 2HDMs

• 3. Tree-level exchange: Radion/Dilaton

Benchmarks: Extended Higgs sectors

Need benchmarks to test the validity

• f the approach

Where/how does the EFT break down? depends on UV completion

50 100 150 200 250 2 4 6 8 10 12 pT HGeVL Nev LHC8 ATLAS VH

¯ cW = 0.1

¯ cW = 0.05

Breakdown depends on loop-induced or tree-level

In a nutshell, we did the matching EFT to UV models and combined EWPTs, Direct searches and Higgs limits in this framework 50 pages of gory details…

For example, for 2HDM

For example, for 2HDM

Matching to EFT: unbroken phase

EWPTs limits

checked the results by matching in the broken theory

For example, for 2HDM

Matching to EFT: unbroken phase

Sensitivity sizeable quartic couplings

• r light particles

Next step quantify the EFT breakdown within these benchmarks

• Mimasu, No, VS. in prep. See also, Brehmer, Freitas, Lopez-Val , Phlehn.1510.03443

Conclusion

Best sensitivity to NP in EFTs requires handling differential distributions Challenges: Precision and breakdown Precision: push understanding of SM and EFTs at higher

• rders, implementation in tools for simulations

Breakdown: model-dependent question. Propose benchmarks, matching between EFT and UV models, include them in tools (e.g. loop-induced requires form- factors), quantify differences

In the Higgs basis

(GeV)

V T

p 200 250 300 350 400 450 500 (GeV)

VH

m 200 300 400 500 600 700 800 900 1000

LHC8

¯ cW = −0.025

Associated production VH

validity distribution

ΛNP ' gNP ( 0.5 TeV )

√c = gNP mW ΛNP

Ellis, VS, You. 1404.3667

black global fit green one-by-one fit

In terms of Higgs’ anomalous couplings