Electroweak Symmetry Breaking via Strong Dynamics in the Precision Higgs Era: Extra Dimension and Composite Higgs Tirtha Sankar Ray XXI DAE-BRNS HEP Symposium, 8-12 December, 2014
The Standard Model All of physics except Gravity? : Then you have : Gauge Hierarchy Fermion Mass Hierarchy Dark Matter Matter Anti-matter Asymmetry Inflation etc...
Natural Models of Electroweak Symmetry Breaking Exactly Unitarized by Higgs Partially Unitarized by Higgs Invoking protective symmetry Chiral symmetry: Supersymmetry Removal of Scale Hierarchy Warped Extra Dimension No Scalar models Technicolor Invoking protective symmetry Shift symmetry : (Higgs as pngb) (1) Little Higgs (2) Composite Higgs Models Realised as dual of 5d Gauge Higgs Unification Models
LHC Data: A Simplified View Observed a Scalar at 126 GeV Assume it to be associated with EWSB Couplings are very close to SM predictions!!
Extra Dimension 4d Strong Dynamics One proposes to expand the number of spatial dimensions from three to four The extra spatial dimension y is compactified on a suitable orbifold with radius of compactification R (-πr y πr) The orbifold is given suitable symmetry (S 1 /Z 2 ) in order to produce chiral fermions By Holography any dynamics in the bulk maps to a strongly coupled CFT in an effective 4d theory Ghergfhetta, arxiv:1008.2570
The Bulk Higgs Consider simpler models of extra dimension where the Higgs is either in the bulk or is quasi-localized in the bulk A holographic approach would lead to a strongly coupled theory of electroweak symmetry breaking Due to symmetries of the metric these theories can be easily solved utilizing the KK decomposition method Every bulk state gets replaced by an infinite tower of increasingly massive states in the effective 4d theory The orbifold fixed points at y=(0,πr) are also locations of two 3-branes. The 5d metric is given by, Mass: No prediction. Just a parameter of the theory. Couplings: Flat Extra Dimension Warped Extra Dimension Loop driven : vulnerable to new states Gluon Photon
Flat Extra Dimension The constraint is 1/R > 1.3 TeV Simple solution including Brane Localized Kinetic Terms: 1/R > 0.4 TeV Gluon Petriello, JHEP 0205:003,2002; Kakuda et al, PRD 88, 035007 (2013) Photon Dey, TSR, Phys.Rev.D88 (2013) 056016
Warped Extra Dimension Custodial Models gg h: Decreases? h γ γ: Increases Imposing KK parity gg h: Increases h γ γ: Increases Gluon Photon Goertz,arXiv:1105.6070 [hep-ph] Considerable constraint on the model Bhattacharyya, TSR, Phys.Lett. B 675 (2009) 222 What happens with BLKT? Work in progress with Ujjal Dey
The Radion Bulk-Higgs Mixing The other way the Higgs coupling can get altered in warped models is by mixing with the radion that is required to stabilize the radius The most generic mixing Lagrangian: Green is the allowed region: Strong constraint for light Radion and low scale of NP Cox, Medina, TSR, Spray, JHEP 1402 (2014) 032 For Brane Higgs see: Sandes, Rosenfeld, P.RD 85, 053003 (2012); Desai, Maitra, Mukhopadhyaya, JHEP10(2013)93
The Composite Higgs The rest of SM The Composite Higgs couples to the SM through Linear Mixing Strong sector responsible for producing the Composite Higgs state Generate Loop driven potential for Higgs a la Coleman-Weinberg Talk by Tony Gherghetta SCGT14 Mini-Workshop, Japan, 2014
The Composite Higgs : Bulk Higgs with Conformal Profile The rest of SM The Composite Higgs couples to the SM through Linear Mixing Can be modelled by a 5d GHU scenario Strong sector responsible for producing the Composite Higgs state Talk by Tony Gherghetta SCGT14 Mini-Workshop, Japan, 2014
The Strong Sector Symmetry Breaking vev Coset Identify your Coset: G /H 1 Choose your Fermion representations Compute the Coleman-Weinberg Potential Contino, arxiv:1005.4269 [hep-ph]
Composite Higgs Models Basic definitions: The Higgs is not a point particle: has a non-trivial shape It is a composite object with a compositeness scale f The Higgs potential is fully or partially generated through radiative corrections Naive Dimensional Analysis tells us: New particle below the cutoff, possible new phenomenology Bellazzini, Csáki and Serra, Eur. Phys. J. C 74 (2014) 5, 2766
Light Higgs: Exotic Resonance Connections Light Higgs demands a light top partner resonance: refer to NDA discussion earlier Δ = 10 % M ρ = 3 TeV Pomarol, Riva, JHEP 1208 (2012) 135 Barnard, Gherghetta, Medina, TSR, JHEP10(2013)055.
The Search for the Resonances Fat KK Gluons are more difficult to see at LHC than anticipated! Azatov, Chowdhury, Ghosh, TSR, Under Preperation. For non Fat KK-Gluons see: Chala et al arxiv:1411.177
Modified Higgs Interactions No chance to explore the scaling of the coupling at LHC/ILC. Can only probe deviations from SM value at low scale. Talk by Grojean, Planck, 2011
Higgs Decay and Couplings At Loop Level Falkowski, Riva, Urbano, arxiv: 1303.1812 Can constrain NP scale up to ~3 TeV at ILC/CLIC
Finally, what if... The Unnatural Composite Higgs Models Flavor Physics prefers NP scale beyond 7 TeV Coset: Fermions: Gauge Coupling Unification Dark Matter Exotic Phenomenology Barnard, Gherghetta, TSR, Spray Arxiv: 1409.7391
Conclusions: Strong Constraints on BSM from Higgs Physics Already at LHC Models SUSY Higgs Mass 126 GeV too heavy Higgs Coupling Can mimic SM in decoupling limit. Main Concern Higgs mass Possible Solutions/ Remarks Tree level contribution from F and D terms or Split Spectrum ED No prediction KK states or Radion mixing can change the couplings Higgs couplings BLKT parameters? Composit -e Higgs 126 GeV bit light Always smaller than SM Both the mass and the couplings Non minimal models, Split Spectrums 5d SUSY 126 GeV too light Can mimic SM Higgs mass Possibly constrained beyond LHC reach Thank you!