THEORETICAL PREDICTIONS FORCOLLIDERSEARCHES · 2015. 12. 2. · 3 LITTLE HIERARCHY LITTLE HIERARCHY...

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1 THEORETICAL PREDICTIONS FOR COLLIDER SEARCHES THEORETICAL PREDICTIONS FOR COLLIDER SEARCHES • “Big” and “little” hierarchy problems • Supersymmetry • Little Higgs • Extra dimensions G.F. Giudice CERN

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+

    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

    ( )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