Presentation on theme: "Non-SUSY Physics Beyond"— Presentation transcript:
1 Non-SUSY Physics Beyond the Standard ModelJ. Hewett, Pre-SUSY 2010
2 Why New Physics @ the Terascale? Electroweak Symmetry breaks atenergies ~ 1 TeV (SM Higgs or ???)WW Scattering unitarized at energies ~ 1 TeV (SM Higgs or ???)Gauge Hierarchy: Nature is fine-tuned or Higgs mass must be stabilized byNew Physics ~ 1 TeVDark Matter: Weakly Interacting Massive Particle must have mass ~ 1 TeV to reproduce observed DM densityAll things point to the Terascale!
3 The Standard ModelBrief review of features which guide & restrict BSM physics
4 The Standard Model on One Page SGauge = d4x FY FY + F F + Fa FaSFermions = d4x fDfSHiggs = d4x (DH)†(DH) – m2|H|2 + |H|4SYukawa = d4x YuQucH + YdQdcH† + YeLecH†( SGravity = d4x g [MPl2 R + CC4] )Generationsf = Q,u,d,L,eThe
5 Standard Model predictions well described by data! EW measurements agree withSM 2+ loop levelJet productionTevatron agree with QCDPull
6 Global Flavor Symmetries SM matter secretly has a large symmetry:Q1u1d1L1e1.. 2. 3Rotate 45 fermions into each otherU(45)Explicitly broken by gauging 3x2x1Rotate among generationsU(3)Q x U(3)u x U(3)d x U(3)L x U(3)eExplicitly broken by quark Yukawas + CKMExplicitly broken by charged lepton YukawasU(1)e x U(1) x U(1)Explicitly broken by neutrino massesU(1)BBaryon NumberLepton NumberU(1)L (Dirac)(or nothing) (Majorana)
7 Global Symmetries of Higgs Sector Four real degrees of freedomHiggs Doublet:Secretly transforms as a12344 of SO(4)Decomposes intosubgroups(2,2) SU(2) x SU(2)SU(2)L of EWLeft-over Global Symmetry
8 Global Symmetries of Higgs Sector Four real degrees of freedomHiggs Doublet:Secretly transforms as aGauging U(1)Y explicitly breaksSize of this breaking given by Hypercharge coupling g’1234SU(2)Global Nothing4 of SO(4)Decomposes intosubgroupsMW g2= 1 as g’0MZ g2 + (g’)2(2,2) SU(2) x SU(2)New Physics may excessively break SU(2)GlobalSU(2)L of EWRemaining Global SymmetryCustodial Symmetry
9 Standard Model Fermions are Chiral Fermions cannot simply ‘pair up’ to form mass termsi.e., mfLfR is forbidden Try it!(Quc) /2(Qdc) /2(QL) /3(Qe) /6(ucdc) x /3(ucL) /6(uce) /3(dcL) /6(dce) /3(Le) /2-SU(3)C SU(2)L U(1)YFermion masses must be generated by Dimension-4 (Higgs) or higher operators to respect SM gauge invariance!------
10 Anomaly Cancellation An anomaly leads to a mass for a gauge boson Quantum violation of current conservationAn anomaly leads to a mass for a gauge boson
11 Anomaly Cancellation SU(3) 3[ 2‧(1/6) – (2/3) + (1/3)] = 0 U(1)Y SU(2)LU(1)Yg3[ 2‧(1/6) – (2/3) + (1/3)] = 0Q uc dcU(1)Y3[3‧(1/6) – (1/2)] = 0Q L3[ 6‧(1/6)3 + 3‧(-2/3)3 + 3‧(1/3)3+ 2‧(-1/2)3 + 13] = 03[(1/6) – (2/3) + (1/3) – (1/2) +1]= 0Q uc dc L eCan’t add any new fermion must be chiral or vector-like!
12 Symmetries of the Standard Model: Summary Gauge SymmetryFlavor SymmetryCustodial SymmetryChiral FermionsGauge AnomaliesSU(3)C x SU(2)L x U(1)YExactBroken to U(1)QEDU(3)5 U(1)B x U(1)L (?)Explicitly broken by YukawasSU(2)Custodial of Higgs sectorBroken by hypercharge so = 1Need Higgs or Higher order operatorsRestrict quantum numbers of new fermions
13 Symmetries of the Standard Model: Summary Gauge SymmetryFlavor SymmetryCustodial SymmetryChiral FermionsGauge AnomaliesSU(3)C x SU(2)L x U(1)YExactBroken to U(1)QEDU(3)5 U(1)B x U(1)L (?)Explicitly broken by YukawasSU(2)Custodial of Higgs sectorBroken by hypercharge so = 1Need Higgs or Higher order operatorsRestrict quantum numbers of new fermionsAny model with New Physics must respect these symmetries
14 Standard Model is an Effective field theory An effective field theory has a finite range of applicability in energy:, Cutoff scaleEnergySM is validParticle massesAll interactions consistent with gauge symmetries are permitted, including higher dimensional operators whose mass dimension is compensated by powers of
16 What sets the cutoff scale ? What is the theory above the cutoff? New Physics, Beyond the Standard Model!Three paradigms:SM parameters are unnaturalNew physics introduced to “Naturalize”SM gauge/matter content complicatedNew physics introduced to simplifyDeviation from SM observed in experiment New physics introduced to explain
17 How unnatural are the SM parameters? Technically NaturalFermion masses(Yukawa Couplings)Gauge couplingsCKMLogarithmicallysensitive to the cutoffscaleTechnically UnnaturalHiggs massCosmological constantQCD vacuum anglePower-law sensitivity to the cutoff scale
18 The naturalness problem that has had the greatest impact on collider physics is: The Higgs (mass)2 problemorThe hierarchy problem
19 The Hierarchy Energy (GeV) 1019 Planck 1016 GUT desert 103 Weak Future Collider Energies103WeakAll of known physicsSolar SystemGravity10-18
20 The Hierarchy Problem Energy (GeV) 1019 Planck Quantum Corrections: Virtual Effects dragWeak Scale to MPl1016GUTdesertFuture Collider EnergiesmH2 ~~ MPl2103WeakAll of known physicsSolar SystemGravity10-18
21 A Cellar of New Ideas ’67 The Standard Model ’77 Vin de Technicolor a classic!aged to perfection’ The Standard Model’ Vin de Technicolor’70’s Supersymmetry: MSSM’90’s SUSY Beyond MSSM’90’s CP Violating Higgs’ Extra Dimensions’ Little Higgs’ Fat Higgs’ Higgsless’ Split Supersymmetry’ Twin Higgsbetter drink nowmature, balanced, welldeveloped - the Wino’s choicesvinters blendall upfront, no finishlacks symmetrybold, peppery, spicyuncertain terriorcomplex structureyoung, still tannicneeds to developsleeper of the vintagewhat a surprise!finely-tuneddouble the tasteJ. Hewett
22 Last Minute Model Building Anything Goes!Non-Communtative GeometriesReturn of the 4th GenerationHidden ValleysQuirks – Macroscopic StringsLee-Wick Field TheoriesUnparticle Physics…..(We stilll have a bit more time)
23 New Physics @ LHC7 Supermodel Discovery Criteria: Large σLHC giving ≥ 10 events at ℒ = 10 pb-1Small σTevatron giving ≤ 10 events with ℒ = 10 fb-1Large BF to easy to detect final stateConsistency with other boundsMost cases controlled byParton fluxSolid: TeV vs TevatronDashed: 10 TeV vs TevatronBauer etal
24 New Physics @ LHC7 Supermodel Discovery Criteria: Large σLHC giving ≥ 10 events at ℒ = 10 pb-1Small σTevatron giving ≤ 10 events with ℒ = 10 fb-1Large BF to easy to detect final stateConsistency with other boundsMost cases controlled byParton fluxNaive, but a reasonable guideSolid: TeV vs TevatronDashed: 10 TeV vs TevatronBauer etal
27 Z’ Resonance: GUT Models LRME6 GUTSLHC7Tevatron BoundsRizzo
28 Extra Dimensions Taxonomy LargeTeVSmallFlatCurvedUEDsRS ModelsGUT ModelsADD Models
29 Extra dimensions can be difficult to visualize One picture: shadows of higher dimensionalobjects2-dimensional shadow of a rotating cube3-dimensional shadow of a rotating hypercube
30 Extra dimensions can be difficult to visualize Another picture: extra dimensions are too smallfor us to observe they are‘curled up’ and compactThe tightrope walker only sees one dimension: back & forth.The ants see two dimensions: back & forth and around the circle
31 Every point in spacetime has curled up extra dimensions associated with it One extra dimension is a circleTwo extra dimensions can be represented by a sphereSix extra dimensions can be represented by a Calabi-Yau space
32 The Braneworld Scenario Yet another pictureWe are trapped on a3-dimensional spatialmembrane and cannot movein the extra dimensionsGravity spreads out andmoves in the extra spaceThe extra dimensions canbe either very small orvery large
33 Are Extra Dimensions Compact? QM tells us that the momentum of a particle traveling along an infinite dimension takes a continuous set of eigenvalues. So, if ED are infinite, SM fields must be confined to 4D OTHERWISE we would observe states with a continuum of mass values.If ED are compact (of finite size L), then QM tells us that p5 takes on quantized values (n/L). Collider experiments tell us that SM particles can only live in ED if 1/L > a few 100 GeV.
36 Kaluza-Klein tower of particles E2 = (pxc)2 + (pyc)2 + (pzc)2 + (pextrac)2 + (mc2)2In 4 dimensions, looks like a mass!Recall pextra = n/RTower of massive particlesSmall radiusLarge radius
37 Kaluza-Klein tower of particles E2 = (pxc)2 + (pyc)2 + (pzc)2 + (pextrac)2 + (mc2)2In 4 dimensions, looks like a mass!Recall pextra = n/RTower of massive particlesSmall radius gives well separated Kaluza-Klein particlesLarge radius gives finely separated Kaluza-Klein particlesSmall radiusLarge radius
38 Action Approach: Consider a real, massless scalar in flat 5-d
39 Masses of KK modes are determined by the interval BC
40 Time-like or Space-like Extra Dimensions ? Consider a massless particle, p2 =0, moving in flat 5-d Then p2 = 0 = pμpμ ± p52 If the + sign is chosen, the extra dimension is time-like, then in 4-d we would interpret p52 as a tachyonic mass term, leading to violations of causality Thus extra dimensions are usually considered to be space-like
41 Higher Dimensional Field Decomposition As we saw, 5d scalar becomes a 4d tower of scalarsRecall: Lorentz (4d) ↔ Rotations (3d)scalar scalar4-vector Aμ A, Φtensor Fμν E, B5d: d ↔ dscalar (scalar)nvector AM (Aμ, A5)ntensor hMN (hμν, hμ5, h55)nKK towers→→→
42 Higher Dimensional Field Decomposition As we saw, 5d scalar becomes a 4d tower of scalarsRecall: Lorentz (4d) ↔ Rotations (3d)scalar scalar4-vector Aμ A, Φtensor Fμν E, B(4+δ)d: (4+δ)d ↔ d (i=1…δ)scalar (δ scalars)nvector AM (Aμ, Ai)nitensor hMN (hμν, hμi, hij)nKK towers1 tensor, δ 4-vectors, ½ δ(δ+1) scalars→→→
43 Experimental observation of KK states: Signals evidence of extra dimensionsProperties of KK states:Determined by geometry of extra dimensions Measured by experiment!The physics of extra dimensions is the physics of the KK excitations
44 What are extra dimensions good for? Can unify the forcesCan explain why gravity is weak (solve hierarchy problem)Can break the electroweak forceContain Dark Matter CandidatesCan generate neutrino masses……Extra dimensions can do everything SUSY can do!
45 If observed: Things we will want to know How many extra dimensions are there?How big are they?What is their shape?What particles feel their presence?Do we live on a membrane?…
46 If observed: Things we will want to know How many extra dimensions are there?How big are they?What is their shape?What particles feel their presence?Do we live on a membrane?…Can we park in extra dimensions?When doing laundry, is that where all the socks go?
47 Searches for extra dimensions Three ways we hope to see extra dimensions:Modifications of gravity at short distancesEffects of Kaluza-Klein particles on astrophysical/cosmological processesObservation of Kaluza-Klein particles in high energy accelerators
48 The Hierarchy Problem: Extra Dimensions Energy (GeV)1019PlanckSimplest Model:Large Extra Dimensions1016GUTdesertFuture Collider Energies103Weak – Quantum Gravity= Fundamental scale in4 + dimensionsMPl2 = (Volume) MD2+Gravity propagates inD = dimensionsAll of known physicsSolar SystemGravity10-18
49 Large Extra Dimensions Arkani-Hamed, Dimopoulos, Dvali, SLAC-PUB-7801Motivation: solve the hierarchy problem by removing it!SM fields confined to 3-braneGravity becomes strong in the bulkGauss’ Law: MPl2 = V MD2+ , V = Rc MD = Fundamental scale in the bulk~ TeVLArg
51 Bulk Metric: Linearized Quantum Gravity Perform Graviton KK reductionExpand hAB into KK towerSM on 3-braneSet T = AB (ya)Pick a gaugeIntegrate over dy Interactions of Graviton KK states with SM fields on 3-brane
52 Feyman Rules: Graviton KK Tower Massless 0-mode + KK states have indentical coupling to matterHan, Lykken, Zhang; Giudice, Rattazzi, Wells
54 Graviton Tower Exchange: XX Gn YY Giudice, Rattazzi, WellsJLHSearch for 1) Deviations in SM processes2) New processes! (gg ℓℓ)Angular distributions reveal spin-2 exchangeMGn are densely packed!(s Rc) states are exchanged! (~1030 for =2 and s = 1 TeV)
59 Graviton Tower Emission Giudice, Ratazzi,WellsMirabelli,Perelstein,Peskine+e- /Z + Gn Gn appears as missing energyqq g + Gn Model independent – Probes MDdirectlyZ ff + Gn Sensitive to Parameterized by density of states:--Discovery reach for MD (TeV):
65 BEWARE! There is a subtlety in this calculation When integrating over the kinematics, we enter a region where the collision energies EXCEED the 4+n-dimensional Planck scaleThis region requires Quantum Gravity or a UV completion to the ADD modelThere are ways to handle this, which result in minor modifications to the spectrum at large ET that may be observable
66 The Hierarchy Problem: Extra Dimensions Energy (GeV)1019PlanckModel II:Warped Extra Dimensions1016GUTstrong curvaturedesertFuture Collider Energies103Weakwk = MPl e-krAll of known physicsSolar SystemGravity10-18
67 Non-Factorizable Curved Geometry: Warped Space Area of each grid is equalField lines spread outfaster with more volume Drop to bottom braneGravity appears weak on top brane!
68 Localized Gravity: Warped Extra Dimensions Randall, SundrumBulk = Slice of AdS55 = -24M53k2k = curvature scaleHierarchy is generated by exponential!Naturally stablized via Goldberger-Wise
69 4-d Effective Theory Phenomenology governed by two parameters: Davoudiasl, JLH, RizzoPhenomenology governed by two parameters: ~ TeVk/MPl ≲ 0.15-d curvature:|R5| = 20k2 < M52
74 Summary of Theory & Experimental Constraints LHC can cover entire allowed parameter space!!
75 Problem with Higher Dimensional Operators Recall the higher dimensional operators that mediate proton decay & FCNCThese are supposed to be suppressed by some high mass scaleBut all high mass scales present in any RS Lagrangian are warped down to the TeV scale.⇒ There is no mechanism to suppress these dangerous operators!Could employ discrete symmetries ala SUSY – but there is a more elegant solution….
76 Peeling the Standard Model off the Brane Model building scenarios require SM bulk fieldsGauge coupling unificationSupersymmetry breaking mass generationFermion mass hierarchySuppression of higher dimensional operatorsStart with gauge fields in the bulk:Gauge boson KK towers have coupling gKK = 8.4gSMPrecision EW Data Constrains: m1A > 25 TeV > 100 TeV!SM gauge fields alone in the bulk violate custodial symmetryDavoudiasl, JLH, RizzoPomarol
78 Schematic of Wavefunctions Can reproduceFermion masshierarchyPlanck braneTeV brane
79 Fermions in the BulkZero-mode fermions couple weaker to gauge KK states than brane fermionstowards Planck branetowards TeV branePrecision EW Constraints
80 Collider Signals are more difficult KK states must couple to gauge fields or top-quark tobe produced at observable rates-gg Gn ZZgg gn ttAgashe, Davoudiasl, Perez, Soni hep-ph/Lillie, Randall, Wang, hep-ph/
81 Black Hole Production @ LHC: Dimopoulos, LandsbergGiddings, ThomasBlack Holes produced when s > MDClassical Approximation: [space curvature << E]E/2b < Rs(E) BH formsbE/2^MBH ~ sGeometric Considerations:Naïve = FnRs2(E), details show this holds up to afactor of a few
83 Potential Corrections to Classical Approximation Distortions fromfinite Rc as Rs Rc2. Quantum Gravity EffectsHigher curvature termcorrectionsRS2/(2Rc)2n =Critical point forinstabilities for n=5:(Rs/Rc)2 ~ @ LHCn =Gauss-Bonnet termn2 ≤ 1 in string models
84 Production rate is enormous! Naïve ~ n for large n1 per sec at LHC!MD = 1.5 TeVJLH, Lillie, Rizzo
85 Black Hole DecayBalding phase: loses ‘hair’ and multiple moments by gravitational radiationSpin-down phase: loses angular momentum by Hawking radiationSchwarzschild phase: loses mass by Hawking radiation – radiates all SM particlesPlanck phase: final decay or stable remnant determined by quantum gravitySpin
86 Decay Properties of Black Holes (after Balding): Decay proceeds by thermal emission of Hawking radiationNot very sensitive to BH rotation for n > 1At fixed MBH, higher dimensional BH’s are hotter:N ~ 1/T higher dimensional BH’s emit fewer quanta, with each quanta having higher energyMultiplicity for n = 2 to n = 6Harris etal hep-ph/
87 Grey-body Factors Particle multiplicity in decay: = grey-body factor Contain energy & anglular emission information
93 Cosmic Ray Sensitivity to Black Hole Production No suppressionRingwald, TuAnchordoqui etal
94 Summary of Exp’t Constraints on MD Anchordoqui, FengGoldberg, Shapere
95 Summary of Physics Beyond the Standard Model There are many ideas for scenarios with new physics! Most of our thinking has been guided by the hierarchy problemThey must obey the symmetries of the SMThey are testable at the LHCWe are as ready for the LHC as we will ever beThe most likely scenario to be discovered at the LHC is the one we haven’t thought of yet.Exciting times are about to begin.Be prepared for the unexpected!!
96 Fine-tuning does occur in nature 2001 solar eclipse as viewed from Africa
97 Most Likely Scenario @ LHC: H. MurayamaMost Likely LHC: