THEORETICAL PREDICTIONS FOR COLLIDER SEARCHES

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THEORETICAL PREDICTIONSFOR COLLIDER SEARCHES
G.F. Giudice CERN

• Big and little hierarchy problems
• Supersymmetry
• Little Higgs
• Extra dimensions

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HIERARCHY PROBLEM
no fine-tuning a LSM lt TeV Big hierarchy
between LSM and MPl Cosmological constant a Cut
off of quartic divergences at Llt10-3 eV
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LITTLE HIERARCHY
10 5.6 9.2 9.7 4.6 7.3
6.1 4.3 4.5 3.2
6.4 9.3 5.0 12.4
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LSMlt1 TeV, LLHgt5-10 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

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SUPERSYMMETRY

• can be extended to MPl
• Link with quantum gravity
• Successful scenario for GUT

exp
exp
Ghilencea-Ross
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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
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SUPERSYMMETRY

• Gauge-coupling unification
• Radiative EW breaking
• Light Higgs
• Satisfies little hierarchy LLH4pLSM
• Dark matter
• Sparticles have not been observed
• Susy-breaking sector unspecified

?
?
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Mc gt 103.5 GeV
Degrassi-Heinemeyer-Hollik-Slavich-Weiglein
9
Giusti-Romanino-Strumia
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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
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NEW INGREDIENTS FROM EXTRA DIMENSIONS
y
Scherk-Schwarz breaking
R
Supersymmetry is broken
Non-local susy breaking _ involves global
structure At short distances (ltR), susy-breaking
effects are suppressed
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NEW INGREDIENTS FROM EXTRA DIMENSIONS
Orbifold projection
Z2 y g-y cos(ny/R)
sin(ny/R)
-
n0
n1
Chiral theories
n1
n2
n2
0
0
pR
pR
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AN INTERESTING EXAMPLE
Barbieri-Hall-Nomura

• 5D SUSY SM compactified on S1/(Z2Z2)
• Different susy breaking at each boundary
• effective theory non-susy
• (susy recovered at dltR)
• 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-Papucc
i
14

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

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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
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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

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HIGGS AS PSEUDOGOLDSTONE BOSON
Gauge, Yukawa and self-interaction are large
non-derivative couplings _ Violate global
symmetry and introduce quadratic div.
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LITTLE HIGGS
Arkani Hamed-Cohen-Georgi
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
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• 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 F1,2
  doublets such that V(F1F1,F2F2) and F1,2
  spontaneously break SU2
• Turning off gauge coupling to F1 _
• Local SU2(F2) global SU2(F1) both spont. broken

Kaplan-Schmaltz
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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-Wac
ker-Low-Skiba-Smith-Kaplan-Schmaltz-Terning
Gauge bosons EW triplet singlet Scalars
(triplets ?)
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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
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HIGGS AS EXTRA-DIM COMPONENT OF GAUGE FIELD

• AM (Am,A5), A5 g A5 ?5 L 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-Sero
ne-Silvestrini
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FLAT Arkani
Hamed-Dimopoulos-Dvali
WARPED Randall-Sundrum
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Contact interactions (loop dominates over tree if
gravity is strong)
Higgs-radion mixing
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Graviton emission Tree-level graviton
exchange Graviton loops Gauge/graviton
loop G.G.-Strumia
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v
Gravitational scattering G.G.-Rattazzi-Wells
Black-hole production Giddings-Thomas,
Dimopoulos-Landsberg
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SM PARTICLES IN EXTRA DIMENSIONS

• Gauge bosons in 5D
• Direct indirect limits Mc gt 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 gt 0.3 TeV
  Appelquist-Cheng-Dobrescu

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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