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THEORETICAL PREDICTIONS FOR COLLIDER SEARCHES

Explore key theoretical predictions for collider searches including hierarchy problems, supersymmetry, little Higgs, and extra dimensions. Discover insights on hierarchy between particles, running from extra dimensions, and unification without desert. Learn about different scenarios, new ingredients from extra dimensions, and collider signals.

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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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