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THEORETICAL PREDICTIONS FOR COLLIDER SEARCHES

THEORETICAL PREDICTIONS FOR COLLIDER SEARCHES. G.F . Giudice CERN. “Big” and “little” hierarchy problems Supersymmetry Little Higgs Extra dimensions. HIERARCHY PROBLEM. no fine-tuning a L SM < TeV “Big” hierarchy between L SM and M Pl Cosmological constant a

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THEORETICAL PREDICTIONS FOR COLLIDER SEARCHES

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  1. THEORETICALPREDICTIONSFORCOLLIDERSEARCHES G.F. Giudice CERN • “Big” and “little” hierarchy problems • Supersymmetry • Little Higgs • Extra dimensions

  2. HIERARCHY PROBLEM nofine-tuning a LSM < TeV “Big” hierarchy between LSM and MPl Cosmological constant a Cut off of quartic divergences at L<10-3 eV

  3. - + LEP1 Bounds on LLH LLH> 5-10TeV LEP2 MFV LITTLE HIERARCHY

  4. LSM<1 TeV, LLH>5-10 TeV “Little” hierarchy between LSM and LLH a • New physics at LSM is weakly interacting • No (sizable) tree-level contributions from new physics at LSM • Strongly-interacting physics can only occur at scales larger than LLH • Successful new physics at LSM has to pass non-trivial tests

  5. t ~ t dmH2 = + H H SUPERSYMMETRY • can be extended to MPl • Link with quantum gravity • Successful scenario for GUT exp exp Ghilencea-Ross

  6. UNIFICATION WITHOUT DESERT Dienes-Dudas-Gherghetta • Accelerated running from extra dimensions • or from gauge group replication • Different tree-level expression for sin2qW GUT: trace over GUT irrep Little running needed Arkani Hamed-Cohen-Georgi Dimopoulos-Kaplan

  7. SUPERSYMMETRY • Gauge-coupling unification • Radiative EW breaking • Light Higgs • Satisfies “little” hierarchy LLH~4pLSM • Dark matter • Sparticles have not been observed • Susy-breaking sector unspecified  

  8. Mc+ > 103.5 GeV Degrassi-Heinemeyer-Hollik-Slavich-Weiglein

  9. Giusti-Romanino-Strumia

  10. Supersymmetry-breaking sector unspecified • Susy flavour violations  gauge, gaugino mediation • Connection with gravity _ supergravity, anomaly mediation • problem _ supergravity Predictivity _ gauge, gaugino, anomaly med. Scenarios with different spectra and different experimental signals

  11. NEW INGREDIENTS FROM EXTRA DIMENSIONS y Scherk-Schwarz breaking R Supersymmetryisbroken Non-local susy breaking _ involves global structure At short distances (<R), susy-breaking effects are suppressed

  12. y y R Z2 NEW INGREDIENTS FROM EXTRA DIMENSIONS Orbifold projection Z2 : y g-y cos(ny/R) sin(ny/R) +- n=0 n=1 Chiral theories n=1 n=2 n=2 0 0 pR pR

  13. AN INTERESTING EXAMPLE Barbieri-Hall-Nomura • 5D SUSY SM compactified on S1/(Z2×Z2) • Different susy breaking at each boundary • effective theory non-susy (susy recovered at d<R) • Higgs boson mass (rather) insensitive to UV • mH = 127 ± 10 GeV • Large corrections to Dr ? • UV completion at L ~ 5 TeV ? Barbieri-Hall-Marandella-Nomura-Okui-Oliver-Papucci

  14. Mass spectrum is non-supersymmetric • one Higgs and two sparticles for each SM particle • LSP stable stop with mass 210 GeV

  15. USING WARPED DIMENSIONS Gherghetta-Pomarol • Susy-breaking in Higgs sector is non-local _ finite effects • AdS/CFT _ SM non-susy • Higgs sector: susy bound states of spontaneously broken CFT • Light Higgs & higgsino • New CFT states at L-1 ~ TeV • Considerable fine tuning SM Susy breaking Higgs sector

  16. SUPERSYMMETRY: CONCLUSIONS • Susy at EW scale can be realized in very different ways: • ETmiss • ETmiss + g • ETmiss + ℓ • Stable charged particle • Nearly-degenerate • Stable stop • Partial susy spectrum

  17. HIGGS AS PSEUDOGOLDSTONE BOSON Gauge, Yukawa and self-interaction are large non-derivative couplings _ Violate global symmetry and introduce quadratic div.

  18. ℒ1 ℒ1 ℒ2 H ℒ2 Arkani Hamed-Cohen-Georgi LITTLE HIGGS A less ambitious programme: Explain only little hierarchy At LSM new physics cancels one-loop power divergences “Collective breaking”: many (approximate) global symmetries preserve massless Goldstone boson

  19. It can be achieved with gauge-group replication • Goldstone bosons in • gauged subgroups, each preserving a non-linear global symmetry • which breaks all symmetries • Field replication Ex. SU2 gauge with F1,2doublets such that V(F1+F1,F2+F2) and F1,2 spontaneously break SU2 • Turning off gauge coupling to F1_ • Local SU2(F2) × global SU2(F1) both spont. broken Kaplan-Schmaltz

  20. Realistic models are rather elaborate Effectively, new particles at the scale f ~ LSM canceling (same-spin) SM one-loop divergences with couplings related by symmetry Typical spectrum: Vectorlike charge 2/3 quark Arkani Hamed-Cohen-Georgi-Katz-Nelson-Gregoire-Wacker-Low-Skiba-Smith-Kaplan-Schmaltz-Terning… Gauge bosons EW triplet + singlet Scalars (triplets ?)

  21. Bounds from: Tevatron limits on new gauge bosons EW data (Dr from new gauge and top) Csaki-Hubisz-Kribs-Meade-Terning In minimal model: Variations significantly reduce the fine tuning

  22. Higgs/gauge unification as graviton/photon unification in Kaluza-Klein gauge Higgs HIGGS AS EXTRA-DIM COMPONENT OF GAUGE FIELD AM = (Am,A5), A5g A5 +∂5L forbids m2A52 • Correct Higgs quantum numbers by projecting out unwanted states with orbifold • Yukawa couplings • Quartic couplings • Do not reintroduce quadratic divergences Csaki-Grojean-Murayama Burdman-Nomura Scrucca-Serone-Silvestrini

  23. EXTRA DIMENSIONS Forget about symmetries, about little hierarchy _ cut off at LSM Any short-distance scale < LSM-1 explained by geometry FLAT Arkani Hamed-Dimopoulos-Dvali WARPED Randall-Sundrum

  24. QUANTUM GRAVITY AT LHC Missing energy (flat) Resonances (warped) Graviton emission H Contact interactions (loop dominates over tree if gravity is strong) Higgs-radion mixing

  25. Graviton emission Tree-level graviton exchange Graviton loops Gauge/graviton loop G.G.-Strumia

  26. As s approaches MD, linearized gravity breaks down _ underlying quantum gravity (strings?) TRANSPLANCKIAN REGIME S>>MD_ RS>>lPl and (semi)classicaleffects dominate over quantum-gravity effects √ b > RS b < RS √ Gravitational scattering G.G.-Rattazzi-Wells Black-hole production Giddings-Thomas, Dimopoulos-Landsberg

  27. SM PARTICLES IN EXTRA DIMENSIONS Gauge bosons in 5D: Direct + indirect limits Mc > 6.8 TeV Cheung-Landsberg At LHC up to 13-15 TeV Weaker bounds in universal extra dimensions After compactification, momentum conservation in 5th dim _ KK number conserved KK particles pair produced; no tree-level exchange Mc > 0.3 TeV Appelquist-Cheng-Dobrescu

  28. SUSY GUT EW E CONCLUSIONS • Many open theoretical options for new physics at EW scale • Direct searches + precision measurements _ no existing theory is completely free of fine-tuning Connection with MPl Gauge coupling unification • ~ LLH or LSM _ Need for UV completion at L

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