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HIGGS PHYSICS

Course on “Weak Interactions in the SM and Beyond” - AA 2022-2023

Roberto Contino

Sapienza Università di Roma

INFN, Roma

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References:

On Higgs cross sections and decay rates

https://twiki.cern.ch/twiki/bin/view/LHCPhysics/LHCHXSWG

Database of ATLAS and CMS results

https://twiki.cern.ch/twiki/bin/view/AtlasPublic

http://cms-results.web.cern.ch/cms-results/public-results/publications/

ATLAS and CMS 10th anniversary papers on Higgs physics

https://www.nature.com/articles/s41586-022-04893-w

https://www.nature.com/articles/s41586-022-04892-x

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Production and Decay

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Production

Total cross section

[From: LHC Higgs Cross Section Working Group]

# Higgs bosons produced at the LHC

Run1 (6fb^-1 @ 7TeV + 23fb^-1 @ 8TeV):

Run2 (~160fb^-1 @ 13TeV):

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Decay: branching ratios and total decay width

Branching Ratios:

Width:

[From: LHC Higgs Cross Section Working Group]

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Events with

Discovery (announced on July 4th, 2012)

Higgs boson first seen in the and channels

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Event Display:

Front view

Side view

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Higgs Couplings: Fits

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Higgs Couplings: Fits

CMS Run 2 (13TeV) 138 fb^-1

ATLAS Run 2 (13TeV) 139 fb^-1

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Higgs Couplings to Fermions

ATLAS,CMS > 5σ

CMS, ATLAS > 5σ

CMS 3.0σ

CMS, ATLAS >5σ

production

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h -> bbar CMS: 5.6sigma (Aug. 2018)

ATLAS: 5.4sigma (Aug. 2018)

h -> tautau CMS: 5.9sigma (Aug. 2017)

ATLAS: 6.4sigma (Nov. 2018)

tth (->bb,WW,ZZ,gaga,tautau) CMS: 5.2sigma (Apr. 2018)

ATLAS: 6.3sigma (Jun. 2018)

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Double Higgs Production

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pp colliders: HH via Gluon Fusion

SM cross section at 14TeV:

Destructive interference between box and triangle

Channel

#events with 3ab^-1

360

10k

1.6k

45k

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Current sensitivity

@ 95% C.L.

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Current sensitivity

Expected precision (HL-LHC)

@ 95% C.L.

[ATL-PHYS-PUB-2017-001]

[arXiv:1811.09689]

@ 95% C.L.

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Double Higgs-strahlung dominates below 1TeV

from arXiv:1311.6528

VBF important above 1TeV

e⁺e^- colliders: HH via Higgs-strahlung and VBF

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com Energy

Process

Precision

ILC

DHS

VBF

Reference

ILC TDR, Volume 2, arXiv:1306.6352

RC, Grojean, Pappadopulo, Rattazzi and Thamm, JHEP 1402 (2014) 006

VBF

P. Roloff (CLICdp Coll.), talk at LCWS14

CLIC

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Effective Lagrangian for a Higgs doublet

Giudice et al. JHEP 0706 (2007) 045

Buchmuller and Wyler NPB 268 (1986) 621

...

Grzadkowski et al. JHEP 1010 (2010) 085

In the unitary gauge: