1
THEORETICAL
PREDICTIONSFOR COLLIDER
SEARCHES
THEORETICAL
PREDICTIONSFOR COLLIDER
SEARCHES• “Big” and “little” hierarchy problems
• Supersymmetry
• Little Higgs
• Extra dimensions
G.F. Giudice CERN
2
HIERARCHY PROBLEMHIERARCHY PROBLEM
2
22222
2
2
GeV200TeV 0.7
123624
SM
tHZWSMF
H mmmmG
m
nofine-tuning SM < TeV
“Big” hierarchy between SM and MPl
Cosmological constant
Cut off of quartic divergences at <10-3 eV
3
LITTLE HIERARCHY 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
FqdH
bbee
ee
LLHDiH
HDH
BWHH
LuudR
uuL
aa
2
55
2
2
1
LEP1
LEP2
MFV
Bounds on LH
LH > 5-10 TeV
+
O2LH
1L
4
SM<1 TeV, LH>5-10 TeV
“Little” hierarchy between SM and LH
•New physics at SM is weakly interacting
•No (sizable) tree-level contributions from new physics at SM
•Strongly-interacting physics can only occur at scales larger than LH
•Successful new physics at SM has to pass non-trivial tests
5
SUPERSYMMETRYSUPERSYMMETRY
mH2 =
H H+
t~
exp
Ghilencea-Ross
t
can be extended to MPl
-Link with quantum gravity
-Successful scenario for GUTexp
6
UNIFICATION WITHOUT DESERTUNIFICATION WITHOUT DESERT
• Accelerated running from extra dimensions• or from gauge group replication• Different tree-level expression for sin2W
GUT: trace over GUT irrep
Little running needed
4
1sin~~,~for
8
3
QTr
Tr sin
2312
12123
2
232
W
W
ggg
USUUSUSU
I
Dienes-Dudas-Gherghetta
Arkani Hamed-Cohen-Georgi
Dimopoulos-Kaplan
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SUPERSYMMETRYSUPERSYMMETRY
• Gauge-coupling unification• Radiative EW breaking• Light Higgs
• Satisfies “little” hierarchy LH~4SM
• Dark matter
• Sparticles have not been observed• Susy-breaking sector unspecified
8
Degrassi-Heinemeyer-Hollik-Slavich-Weiglein
MGeV
9
Giusti-Romanino-Strumia
%3sun
moonsun
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
y
R
NEW INGREDIENTS FROM EXTRA DIMENSIONSNEW INGREDIENTS FROM EXTRA DIMENSIONS
Scherk-Schwarz breaking
symmetry -R is Q If
)(),(
conditionsboundary with expansion KK
),()2,(
2
22//
2
R
Qnmxeeyx
yxeRyx
nnn
RinyRyiQ
iQ
Supersymmetry is broken
Non-local susy breaking involves global structure
At short distances (<R), susy-breaking effects are suppressed
12
y
R yZ2
NEW INGREDIENTS FROM EXTRA DIMENSIONSNEW INGREDIENTS FROM EXTRA DIMENSIONS
Orbifold projection
R 0
n=1
n=2
0
n=0n=1
n=2
R
Z2 : y y cos(ny/R) sin(ny/R)
Chiral theories
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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 ?
UV completion at ~ 5 TeV ?
AN INTERESTING EXAMPLEAN INTERESTING EXAMPLE
Barbieri-Hall-Nomura
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
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USING WARPED DIMENSIONSUSING WARPED DIMENSIONS•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
states bound of size 4
1 11 LLmEW
Susy breaking
Higgs sector
SM
Gherghetta-Pomarol
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SUPERSYMMETRY:
CONCLUSIONS
SUPERSYMMETRY:
CONCLUSIONSSusy at EW scale can be realized in very different ways:
•ETmiss
• ETmiss +
•ETmiss + ℓ
•Stable charged particle
•Nearly-degenerate
•Stable stop
•Partial susy spectrum
0~ W
17
HIGGS AS PSEUDOGOLDSTONE BOSON
HIGGS AS PSEUDOGOLDSTONE BOSON
22
/
forbids
symmetry realizedlinearly -Non
:
2
hmahh
ae
fef
ia
fi
Gauge, Yukawa and self-interaction are large non-derivative couplings
Violate global symmetry and introduce quadratic div.
18
A less ambitious programme:
Explain only little hierarchy
At SM new physics cancels one-loop power divergences
LITTLE HIGGSLITTLE HIGGS
LH
224
4
22
222
2
TeV10 loops Two
TeV loop One
SMFSM
FH
F
SMSMSMF
H
mGm
Gm
Gm
Gm
“Collective breaking”: many (approximate) global symmetries preserve massless Goldstone bosonℒ1ℒ
2
H2
222
44
Hm
ℒ1 ℒ2
Arkani Hamed-Cohen-Georgi
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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 doublets such that V(
) and
spontaneously break SU2
Turning off gauge coupling to
Local SU2(2) × global SU2() both spont. broken
HG /
21 GGG
21SM GG
loops two
42
4
42
gmH
Kaplan-Schmaltz
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Realistic models are rather elaborate
Effectively, new particles at the scale f ~ SM
canceling (same-spin) SM one-loop divergences with couplings related by symmetry
Typical spectrum:
Vectorlike charge 2/3 quark
Gauge bosons EW triplet + singlet
Scalars (triplets ?)
Arkani Hamed-Cohen-Georgi-Katz-Nelson-Gregoire-Wacker-Low-Skiba-Smith-Kaplan-Schmaltz-Terning…
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tuning-fine %1.0TeV 5
TeV 1422
ff
v
mm t
t
Bounds from: Tevatron limits on new gauge bosons
EW data ( from new gauge and top)
In minimal model:
Variations significantly reduce the fine tuning
Csaki-Hubisz-Kribs-Meade-Terning
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HIGGS AS EXTRA-DIM COMPONENT
OF GAUGE FIELD
HIGGS AS EXTRA-DIM COMPONENT
OF GAUGE FIELDAM = (A,A5), A5 A5 +∂5 forbids m2A5
2
gauge HiggsHiggs/gauge unification as graviton/photon unification in Kaluza-Klein
Higgs/gauge unification as graviton/photon unification in Kaluza-Klein
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
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EXTRA DIMENSIONSEXTRA DIMENSIONSForget about symmetries, about little hierarchy
cut off at SM Any short-distance scale < SM
-1 explained by geometry
42/12/ DMRM DPl
KRPl eMM 5
FLAT Arkani Hamed-Dimopoulos-Dvali
WARPED Randall-Sundrum
24H
QUANTUM GRAVITY AT LHCQUANTUM GRAVITY AT LHC
Graviton emissionMissing energy (flat)
Resonances (warped)
TT
4
1
252
1ff
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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√As s approaches MD, linearized gravity breaks down
underlying quantum gravity (strings?)
TRANSPLANCKIAN REGIMES>>MD RS>>Pl and (semi)classical effects dominate
over quantum-gravity effects
b > RS
b < RS
Gravitational scatteringG.G.-Rattazzi-Wells
Black-hole productionGiddings-Thomas, Dimopoulos-Landsberg
√
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SM PARTICLES IN EXTRA DIMENSIONS
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
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CONCLUSIONSCONCLUSIONS
• Many open theoretical options for new physics at EW scale
• Direct searches + precision measurements no existing theory is completely free of fine-tuning
EWSUSY
GUT
E
Connection with MPl
Gauge coupling unification
Connection with MPl
Gauge coupling unification
LH orSM Need for UV
completion at