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Way Beyond the SM

Way Beyond the SM. G.F. Giudice. IoP meeting on the Physics of the ILC Oxford, 23 May 2007. Original work with C. Grojean, A. Pomarol, R. Rattazzi. Supersymmetry is still the most “credible” theory BSM. gauge-coupling unification EW breaking triggered by dynamics dark-matter candidate

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Way Beyond the SM

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  1. Way Beyond the SM G.F. Giudice IoP meeting on the Physics of the ILC Oxford, 23 May 2007 Original work with C. Grojean, A. Pomarol, R. Rattazzi

  2. Supersymmetry is still the most “credible” theory BSM • gauge-coupling unification • EW breaking triggered by dynamics • dark-matter candidate • pass EW tests But, increasing difficulty with direct limits  % tuning Reason to look “way beyond”

  3. Extra dimensions have brought new theoretical tools Exciting new phenomena: graviton emission, transplanckian scattering, black-hole production They require the largest possible energy: is LHC enough? Nevertheless, ILC can give complementary information, especially for indirect signals Weiglein et al., 2004 Some of the most interesting twists of extra dimension are related to EW breaking

  4. Warped gravity with SM fermions and gauge bosons in bulk and Higgs on brane Technicolor-like theory with slowly-running couplings in 4 dim TeV brane Planck brane 5th dim RG flow IR UV AdS/CFT correspondence relates 5-d gravity with negative cosmological constant to strongly-coupled 4-d conformal field theory 5-D gravity4-D gauge theory Motion in 5th dimRG flow UV branePlanck cutoff IR branebreaking of conformal inv. Bulk local symmetriesglobal symmetries Technicolor strikes back?

  5. DUALITY: familiar conceptual distinction between force and spatial dimension becomes blurry Is it a particle or is it a wave?

  6. TC Technicolor-like theories in new disguise Old problems The presence of a light Higgs helps • Light Higgs screens IR contributions to S and T • (f pseudo-Goldstone decay constant) Can be tuned small for strong dynamics 4f at few TeV

  7. ➤ Top sector ● ● ➤ No fine-tuning New constructions with light Higgs & strong dynamics Higgs as pseudogoldstone boson Gauge, Yukawa and self-interaction are non-derivative couplings _Violate global symmetry and introduce quadratic divergences Strong dynamics at a low scale, in conflict with LEP data

  8. ℒ1 ℒ1 ℒ2 H ℒ2 LITTLE HIGGS: delays strong dynamics by cancelling one-loop effects only “Collective breaking”: many (approximate) global symmetries preserve massless Goldstone boson New states at TeV reduce UV sensitivity of mH

  9. gauge Higgs HIGGS AS EXTRA-DIM COMPONENT OF GAUGE FIELD AM = (Am,A5), A5g A5 +∂5L forbids m2A52 Higgs/gauge unification as graviton/photon unification in KK Correct Higgs quantum numbers by projecting out unwanted states with orbifold The difficulty is to generate Yukawa and quartic couplings without reintroducing quadratic divergences

  10. Light Higgs pseudoGoldstone of a strong force Belong to higher-dim gauge multiplet Same thing? (duality) Relation between models of strong dynamics and extra dimensions Common low-energy theory of Higgs interactions (particularly useful for linear collider, as S,T useful parametrization of new physics at LEP) Higgs is the 4th Goldstone

  11. strong sector quarks, leptons & gauge bosons Structure of the theory Communicate via gauge (ga) and (proto)-Yukawa(i) mmass of resonances gcoupling of resonances Strong sector characterized by Take I, ga << g< 4 In the limit I, ga =0, strong sector contains Higgs as Goldstone bosons Ex. H = SU(3)/SU(2)U(1) or H = SO(5)/SO(4) -model with f =m/ g

  12. ga , i break global symmetry  Higgs mass New theory addresses hierarchy problem  reduced sensitivity of mH to short distances (below m-1) • Ex.: • Georgi-Kaplan: g=4, f = v, no separation of scales • Holographic Higgs: g= gKK, m= mKK • Little Higgs: g, mcouplings and masses of new t’, W’, Z’

  13. Production of resonances at m allows to test models at the LHC Study of Higgs properties allows a model independent test of the nature of the EW breaking sector Is the Higgs composite? Holographic Higgs Gauge-Higgs unification Little Higgs fundamental? SM (with mH < 180 GeV) supersymmetry ILC can give a fundamental contribution to answer this question

  14. Construct the Lagrangian of the effective theory below m • From the kinetic term, we obtain the definition of f = m / g • Each extra H insertion gives operators suppressed by 1 / f • Each extra derivative “ “ 1 / m f: symmetry-breaking scale m: new-physics mass threshold • Operators that violate Goldstone symmetry are suppressed by corresponding (weak) coupling

  15. Operators testing the strong self coupling of the Higgs(determined by the structure of the  model)  and yf are SM couplings; ci model-dependent coefficients Form factors sensitive to the scale m Loop-suppressed strong dynamics

  16. Effects in Higgs production and decay All Higgs couplings rescaled by Modified Higgs couplings to matter

  17. Dührssen 2003 SLHC Report 2002

  18. LHC can measure cHv2/f2 and cyv2/f2 up to 20-40% SLHC can improve it to about 10% A sizeable deviation from SM in the absence of new light states would be indirect evidence for the composite nature of the Higgs ILC can test v2/f2 up to the % level ILC can explore the Higgs compositeness scale 4f up to 30 TeV !! ECFA/DESY LC Report 2001

  19. Effective-theory approach is half-way between model-dependent and operator analyses • Dominant effects come from strong self-Higgs interactions characterized by • From operator analyses, Higgs processes loop-suppressed in SM are often considered most important for searches • However, operators h and hgg are suppressed 1/(162m2) • Since h is charge and color neutral, gauging SU(3)cU(1)Q does not break the generator under which h shifts (Covariant derivative acting on hdoes not contain  or g) • Not the case for hZ (loop, but not 1/gsuppressed)

  20. Higgs decay rates

  21. WL WL h WL WL Modified coupling Genuine signal of Higgs compositeness at high energies In spite of light Higgs, longitudinal gauge-boson scattering amplitude violate unitarity at high energies LHC with 200 fb-1 sensitive up to cH0.3

  22. Higgs is viewed as pseudoGoldstone boson: its properties are related to those of the exact (eaten) Goldstones: O(4) symmetry Strong gauge-boson scattering strong Higgs production Can bbbb at high invariant mass be separated from background? h  WW  leptons is more promising Sum rule (with cuts |and s<M2):

  23. In many realizations, the top quark belongs to the strongly-coupled sector At leading order in 1/f2 Modified top-quark couplings to h and Z At ILC ghtt up to 5% with s=800 GeV and L=1000 fb-1 From gZtt, cR ~ 0.04 with s=500 GeV and L=300 fb-1(no accuracy at LHC) FCNC effects

  24. CONCLUSIONS • Several new classes of theories with light Higgs and strong interactions • Experimental question: is Higgs fundamental or composite? • Model-independent approach to characterize its phenomenological consequences • Modifications of Higgs production and decay rates, strong WW scattering, strong Higgs production • ILC can help significantly in settling the issue

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