# 4th TLEP workshop ( EuCARD-AccNet )

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### Transcript of 4th TLEP workshop ( EuCARD-AccNet )

Phenomenology Beyond the Standard Model

4th TLEP workshop (EuCARD-AccNet)John EllisKings College London(& CERN)Physics Overview1Couplings proportional to masses (?)

Important couplings through loops:gluon + gluon Higgs

Higgs Decay Branching RatiosMany decay modes measurable if Mh ~ 125 GeV2

Unofficial Combination of Higgs Search Data from March 6thIs this theHiggs Boson?No Higgs here!NoHiggshere!

Couplings resemble Higgs of Standard ModelNo indication of any significant deviation from the Standard Model predictionsJE & Tevong You, arXiv:1303.3879

Some QuestionsWhat is it?Higgs or ?What else is there?Supersymmetry or ?What next?A Higgs factory or ?What is it ?Does it have spin 0 or 2?

Is it scalar or pseudoscalar?

Is it elementary or composite?

Does it couple to particle masses?

Quantum (loop) corrections?

What are its self-couplings?The Higgs Spin is probably 0Graviton-like spin-2 disfavoured at 98.5% CL

What is it ?Does it have spin 0 or 2?Spin 2 very unlikelyIs it scalar or pseudoscalar?

Is it elementary or composite?

Does it couple to particle masses?

Quantum (loop) corrections?

What are its self-couplings?Pseudoscalar 0- disfavoured at > 99% CLThe Higgs is probably a scalar

9What is it ?Does it have spin 0 or 2?Spin 2 seems unlikely, but needs experimental checksIs it scalar or pseudoscalar?Pseudoscalar disfavoured by experimentIs it elementary or composite?

Does it couple to particle masses?

Quantum (loop) corrections?

What are its self-couplings?General Analysis of unHiggs ModelsParametrization of effective Lagrangian:

Fits

Azatov, Contino, Galloway: arXiv:1202.3415

a cCMS fit assuming c > 0caGlobal Analysis of Higgs-like ModelsRescale couplings: to bosons by a, to fermions by c

Standard Model: a = c = 1JE & Tevong You, arXiv:1303.3879

b bbar

W W

Z Z

GlobalWhat is it ?Does it have spin 0 or 2?Spin 2 seems unlikely, but needs experimental checksIs it scalar or pseudoscalar?Pseudoscalar disfavoured by experimentIs it elementary or composite?No significant deviations from Standard ModelDoes it couple to particle masses?

Quantum (loop) corrections?

What are its self-couplings?It Walks and Quacks like a HiggsDo couplings scale ~ mass? With scale = v?

Red line = SM, dashed line = best fit

JE & Tevong You, arXiv:1303.3879Globalfit

What is it ?Does it have spin 0 or 2?Spin 2 seems unlikely, but needs experimental checksIs it scalar or pseudoscalar?Pseudoscalar disfavoured by experimentIs it elementary or composite?No significant deviations from Standard ModelDoes it couple to particle masses?Some prima facie evidence that it doesQuantum (loop) corrections?

What are its self-couplings?Loop Corrections ?ATLAS sees excess in , CMS sees deficit

Loop diagrams ~ Standard Model?

JE & Tevong You, arXiv:1303.3879What is it ?Does it have spin 0 or 2?Spin 2 seems unlikely, but needs experimental checksIs it scalar or pseudoscalar?Pseudoscalar disfavoured by experimentIs it elementary or composite?No significant deviations from Standard ModelDoes it couple to particle masses?Some prima facie evidence that it doesQuantum (loop) corrections? coupling > Standard Model?What are its self-couplings?Theoretical Constraints on Higgs MassLarge Mh large self-coupling blow up at low-energy scale due to renormalizationSmall: renormalization due to t quark drives quartic coupling < 0at some scale vacuum unstableVacuum could be stabilized by SupersymmetryDegrassi, Di Vita, Elias-Miro, Giudice, Isodori & Strumia, arXiv:1205.6497

18Vacuum Instability in the Standard Model Very sensitive to mt as well as MH

Present vacuum probably metastable with lifetime >> age of the Universe

Degrassi, Di Vita, Elias-Miro, Giudice, Isodori & Strumia, arXiv:1205.649719What else is there?LHC may reveal new physics when it restarts at higher energyDo not mortgage future of HEP before we know

Successful prediction for Higgs massShould be < 130 GeV in simple modelsSuccessful predictions for couplingsShould be within few % of SM values

Gluino massBuchmueller, JE et al: arXiv:1207.3715CMSSMSupersymmetry20Maybe it is a Supersymmetric Duck?Fits with lighter/heavier scalar Higgs at 125 GeV

Bechtle et al., arXiv:1211.1955LighterHeavierMaybe it is a Supersymmetric Duck?Fits with lighter/heavier scalar Higgs at 125 GeV

Bechtle et al., arXiv:1211.1955LighterHeavierWhat Next: A Higgs Factory?To study the Higgs in detail:The LHCRethink LHC upgrades in this perspective?A linear collider?ILC up to 500 GeVCLIC up to 3 TeV(Larger cross section at higher energies)A circular e+e- collider: TLEP, A photon-photon collider: SAPPHiREA muon collider

23

Higgs Factory SummaryICFA Higgs Factory WorkshopFermilab, Nov. 2012Bestprecision24Predictions of current best fits in simple modelsCurrent uncertainties in SM calculations [LHC Higgs WG] (important correlations)Comparisons withLHCHL-LHCILCTLEP

Impact of Higgs Factory?25No serious studies yet: refer back to GigaZ studiesIssues in LEP/SLC data at Z peakBig improvement possible at GigaZ

BUT em, MZ, higher-order EW Impact of TeraZ& GigaW

Heinemeyer & Weiglein, arXiv:1007.523226Precision at TeraZ/GigaW?Estimates using MH, MZ, em, mt, s:MW = 80.361 0.006 0.004 GeV (parametric) (higher-order EW)sin2eff = 0.23152 0.00005 0.00005 (parametric) (higher-order EW)GigaZ/MegaW aim at MW = 7 MeV, sin2eff = 10-5What can be done with TeraZ/GigaW?Much theoretical work also needed!

Ferroglia & Sirlin, arXiv:1211.1864SummaryBeyond any reasonable doubt, the LHC has discovered a (the) Higgs bosonThe LHC may discover physics beyond the SM when it restarts at ~ 13 TeVIf it does, priority will be to study itIf it does not, natural to focus on the HiggsIn this case, TLEP offers the best prospectsand also other high-precision physicsA severe test also for theoretical physics