THEORETICAL PREDICTIONS FORCOLLIDERSEARCHES · 2015. 12. 2. · 3 LITTLE HIERARCHY LITTLE HIERARCHY...
Transcript of THEORETICAL PREDICTIONS FORCOLLIDERSEARCHES · 2015. 12. 2. · 3 LITTLE HIERARCHY LITTLE HIERARCHY...
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THEORETICAL PREDICTIONSFOR COLLIDER SEARCHES
THEORETICAL PREDICTIONSFOR COLLIDER SEARCHES
• “Big” and “little” hierarchy problems
• Supersymmetry
• Little Higgs
• Extra dimensions
G.F. Giudice CERN
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HIERARCHY PROBLEMHIERARCHY PROBLEM( )
2
22222
22
GeV200TeV 0.7
123624
Λ−=
−++= Λ
SM
tHZWSMF
H mmmmGm
πδ
no fine-tuning ΛSM < TeV
“Big” hierarchy between ΛSM and MPl
Cosmological constant
Cut off of quartic divergences at Λ
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LITTLE HIERARCHY LITTLE HIERARCHY
5.0
12.4
6.4
9.3
4.5
3.2
6.1
4.3
9.7
4.6
7.3
10
5.6
9.2
( )µν
µν
µ
µµ
µµ
µµ
µ
µνµν
σλλλ
γλλ
γγγγ
γγ
γ
τ
FqdH
qq
bbee
ee
LLHDiH
HDH
BWHH
LuudR
uuL
aa
++
+
+
+
+
2
55
2
21
ll
LEP1
LEP2
MFV
Bounds on ΛLH
ΛLH > 5-10 TeV
− +
O2LH
1LΛ
±=
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ΛSM5-10 TeV
“Little” hierarchy between ΛSM and ΛLH
•New physics at ΛSM is weakly interacting
•No (sizable) tree-level contributions from new physics at ΛSM•Strongly-interacting physics can only occur at scales larger than ΛLH•Successful new physics at ΛSM has to pass non-trivial tests
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SUPERSYMMETRYSUPERSYMMETRY
δmH2 = H H+
t~
exp
t
Λ can be extended to MPl-Link with quantum gravity
-Successful scenario for GUTexp
Ghilencea-Ross
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UNIFICATION WITHOUT DESERTUNIFICATION WITHOUT DESERT
• Accelerated running from extra dimensions• or from gauge group replication• Different tree-level expression for sin2θWGUT: trace over GUT irrep
Little running needed41sin~~,~for
83
QTr Tr sin
2312
12123
2
232
=⇒>>
×→××
==
W
W
ggg
USUUSUSU
I
θ
θ
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 ΛLH~4πΛSM• Dark matter
• Sparticles have not been observed• Susy-breaking sector unspecified
☺
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Degrassi-Heinemeyer-Hollik-Slavich-Weiglein
Mχ+ > 103.5 GeV
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Giusti-Romanino-Strumia
%3sun
moonsun =−
θθθ
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Supersymmetry-breaking sector unspecified
Susy flavour violations gauge, gaugino mediation
Connection with gravity supergravity, anomaly mediation
µ problem supergravity
Predictivity gauge, gaugino, anomaly med.
Scenarios with different spectra and different experimental signals
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( )
symmetry -R is Q If
)(),(
conditionsboundary with expansion KK ),()2,(
2
22//
2
⇒
+=⇒Φ=Φ
Φ=+Φ
Φ∞+
−∞=∑Φ
Φ
RQnmxeeyx
yxeRyx
nnn
RinyRyiQ
iQππ
Supersymmetry is broken
yR
NEW INGREDIENTS FROM EXTRA DIMENSIONSNEW INGREDIENTS FROM EXTRA DIMENSIONS
Scherk-Schwarz breaking
Non-local susy breaking involves global structure
At short distances (
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yR y
Z2
NEW INGREDIENTS FROM EXTRA DIMENSIONSNEW INGREDIENTS FROM EXTRA DIMENSIONS
Orbifoldprojection
πR 0
n=1
n=2
0
n=0n=1
n=2
πR
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
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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 DIMENSIONSGherghetta-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
states bound of size 41 11 −−= LLmEW π
Susybreaking
Higgs sector
SM
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SUPERSYMMETRY: CONCLUSIONS
SUPERSYMMETRY: CONCLUSIONS
Susy at EW scale can be realized in very different ways:•ETmiss
• ETmiss + γ
•ETmiss + ℓ
•Stable charged particle
•Nearly-degenerate
•Stable stop
•Partial susy spectrum
0~ ±W
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HIGGS AS PSEUDOGOLDSTONE BOSONHIGGS AS PSEUDOGOLDSTONE BOSON
22
/
forbids symmetry realizedlinearly -Non
:
2
hmahh
ae
fef
ia
fi
+→
+→→
Φ→Φ
=Φ+
=Φ
θθρρ
ρ θ
Gauge, Yukawa and self-interaction are large non-derivative couplings
Violate global symmetry and introduce quadratic div.
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A less ambitious programme:
Explain only little hierarchy
At ΛSM new physics cancels one-loop power divergences
LITTLE HIGGSLITTLE HIGGS
LH
224
4
22
222
2
TeV10 loops Two
TeV loop One
Λ≈≈≈Λ⇒Λ=
≈
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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 Φ1,2doublets such that V(Φ1+Φ1,Φ2+Φ2) and Φ1,2 spontaneously break SU2Turning off gauge coupling to Φ1
Local SU2(Φ2) × global SU2(Φ1) both spont. broken
HG /
21 GGG ×⊃
21SM GG ×⊂
( )loops two
42
4
42 Λ≈
πδ gmH
Kaplan-Schmaltz
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Realistic models are rather elaborate
Effectively, new particles at the scale f ~ ΛSM 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 ?)
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tuning-fine %1.0TeV 5
TeV 1422 ⇒
=>′
ffvmm tt
In minimal model:
Variations significantly reduce the fine tuning
Bounds from: Tevatron limits on new gauge bosons
EW data (∆ρ from new gauge and top)
Csaki-Hubisz-Kribs-Meade-Terning
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HIGGS AS EXTRA-DIM COMPONENT OF GAUGE FIELD
HIGGS AS EXTRA-DIM COMPONENT OF GAUGE FIELD
AM = (Aµ,A5), A5 A5 +∂5 Λ forbids m2A52
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 ΛSM Any short-distance scale < ΛSM-1 explained by geometry
δδδ +=≈ + 42/12/ DMRM DPl
πKRPl eMM
−≈ 5
FLAT Arkani Hamed-Dimopoulos-Dvali
WARPED Randall-Sundrum
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QUANTUM GRAVITY AT LHCQUANTUM GRAVITY AT LHC
Graviton emissionMissing energy (flat)
Resonances (warped)
µνµνTT4
1Λ
( )2521 ff γγ µΛ
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>>λPl 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 DIMENSIONSSM PARTICLES IN EXTRA DIMENSIONS
Gauge bosons in 5D:Direct + indirect limits Mc > 6.8 TeV Cheung-LandsbergAt LHC up to 13-15 TeV
Weaker bounds in universal extra dimensionsAfter compactification, momentum conservation in 5th dim KK number conserved
KK particles pair produced; no tree-level exchangeMc > 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 MPlGauge coupling unification
Connection with MPlGauge coupling unification
Λ ∼ ΛLH or ΛSM Need for UV
completion at Λ
THEORETICAL PREDICTIONSFOR COLLIDER SEARCHESHIERARCHY PROBLEMLITTLE HIERARCHYSUPERSYMMETRYUNIFICATION WITHOUT DESERTSUPERSYMMETRYSupersymmetry-breaking sector unspecifiedHIGGS AS PSEUDOGOLDSTONE BOSONLITTLE HIGGSHIGGS AS EXTRA-DIM COMPONENT OF GAUGE FIELDSM PARTICLES IN EXTRA DIMENSIONSCONCLUSIONS