The SLED Proposal Arkani-Hamad, Dimopoulos & Dvali • Suppose physics is • Experimentally possible: extra-dimensional • There are precisely two above the 10 -2 eV scale. extra dimensions at these scales; • We are brane bound; • The 6D gravity scale is in • Suppose the physics of the TeV region. the bulk is = 2 M M r supersymmetric. p g Moriond 2007
The SLED Proposal • Suppose physics is • Bulk supersymmetry extra-dimensional above • Graviton has many the 10 -2 eV scale. partners in the extra dimensions • Suppose the physics of the bulk is supersymmetric. Moriond 2007
The SLED Proposal • Suppose physics is • Bulk supersymmetry extra-dimensional above • SUSY breaks at scale M g the 10 -2 eV scale. on the branes; • Trickle-down of SUSY breaking to the bulk is: • Suppose the physics of 2 the bulk is M 1 − ≈ ≈ ≈ g 2 m 10 eV supersymmetric. SB M r p Moriond 2007
The SLED Proposal Particle Spectrum: SM on brane – no partners M w Many KK modes in bulk 2 /M p m ~ M w 4D scalar: e φ r 2 ~ const H ~ m 2 /M p 4D graviton Moriond 2007
The SLED Proposal M w 2 /M p m ~ M w These scales are natural using H ~ m 2 /M p standard 4D arguments. Moriond 2007
The SLED Proposal Must rethink how the vacuum gravitates in M w 6D for these scales. SM interactions do not change at all! 2 /M p m ~ M w These scales are natural using H ~ m 2 /M p standard 4D arguments. Moriond 2007
The Plan • Motivation • Reading the Tea Leaves • The SLED Proposal • Changing how the vacuum energy gravitates • Worries • Naturalness; Runaways; Stabilizing dimensions; No-Go arguments; pre-BBN cosmology; Constraints on new forces,… • Observational Tests • Cosmology; Tests of Gravity; LHC; Particle Phenomenology; Neutrino Oscillations?… • Summary Moriond 2007
The Worries • ‘Technical Naturalness’ • Runaway Behaviour • Stabilizing the Extra Dimensions • Famous No-Go Arguments • Problems with Cosmology • Constraints on Light Scalars Moriond 2007
The Worries • ‘Technical Naturalness’ • Runaway Behaviour • Stabilizing the Extra Dimensions • Famous No-Go Arguments • Problems with Cosmology • Constraints on Light Scalars Moriond 2007
The Worries • ‘Technical Naturalness’ • Classical part of the argument: • What choices must be made to ensure 4D • Runaway Behaviour flatness? • Stabilizing the Extra Dimensions • Quantum part of the argument: • Are these choices stable against • Famous No-Go Arguments renormalization? • Problems with Cosmology • Constraints on Light Scalars Moriond 2007
The Worries Tolley, CB, Hoover & Aghababaie Tolley, CB, de Rham & Hoover • ‘Technical Naturalness’ • Classical part of the argument: • What choices must be made to ensure 4D • Runaway Behaviour flatness? Now understand how 2 extra • Stabilizing the Extra Dimensions dimensions respond to presence of 2 branes having arbitrary couplings. • Famous No-Go Arguments • Not all are flat in 4D, but all of those having only conical singularities are flat. • Problems with Cosmology (Conical singularities correspond to absence of dilaton couplings to branes) • Constraints on Light Scalars Moriond 2007
The Worries • ‘Technical Naturalness’ • Quantum part of the argument: • Are these choices stable against • Runaway Behaviour renormalization? • Stabilizing the Extra Dimensions So far so good, but not yet complete • Brane loops cannot generate dilaton • Famous No-Go Arguments couplings if these are not initially present • Bulk loops can generate such couplings, but are suppressed by 6D supersymmetry • Problems with Cosmology • Constraints on Light Scalars Moriond 2007
The Plan • Motivation • Reading the Tea Leaves • The SLED Proposal • Changing how the vacuum energy gravitates • Worries • Naturalness; Runaways; Stabilizing dimensions; No-Go arguments; pre-BBN cosmology; Constraints on new forces,… • Observational Tests • Cosmology; Tests of Gravity; LHC; Particle Phenomenology; Neutrino Oscillations?… • Summary Moriond 2007
The Observational Tests • Quintessence cosmology Moriond 2007
The Observational Tests • Quintessence cosmology • Modifications to gravity Moriond 2007
The Observational Tests • Quintessence cosmology • Modifications to gravity • Collider physics Moriond 2007
The Observational Tests • Quintessence cosmology • Modifications to gravity • Collider physics SUSY broken at the TeV scale, but not the MSSM! Moriond 2007
The Observational Tests • Quintessence cosmology • Modifications to gravity • Collider physics • Neutrino physics? Moriond 2007
The Observational Tests • Quintessence cosmology • Modifications to gravity • Collider physics • Neutrino physics? • And more! Moriond 2007
The Plan • Motivation • Reading the Tea Leaves • The SLED Proposal • Changing how the vacuum energy gravitates • Worries • Naturalness; Runaways; Stabilizing dimensions; No-Go arguments; pre-BBN cosmology; Constraints on new forces,… • Observational Tests • Cosmology; Tests of Gravity; LHC; Particle Phenomenology; Neutrino Oscillations?… • Summary Moriond 2007
Summary • 6D braneworlds allow progress on the cosmological constant problem: • Vacuum energy not equivalent to curved 4D • ‘Flat’ choices stable against renormalization? Moriond 2007
Summary • 6D braneworlds allow progress on the cosmological constant problem: • Vacuum energy not equivalent to curved 4D • ‘Flat’ choices stable against renormalization? • Tuned initial conditions • Much like for the Hot Big Bang Model.. Moriond 2007
Summary • 6D braneworlds allow progress on the cosmological constant problem: • Vacuum energy not equivalent to curved 4D • ‘Flat’ choices stable against renormalization? • Tuned initial conditions • Much like for the Hot Big Bang Model.. • Enormously predictive, with many observational consequences. • Cosmology at Colliders! Tests of gravity… Moriond 2007
Detailed Worries and Observations • Quintessence cosmology • ‘Technical Naturalness’ • Runaway Behaviour • Modifications to gravity • Stabilizing the Extra Dimensions • Collider physics • Famous No-Go Arguments • Neutrino physics? • Problems with Cosmology • Constraints on Light Scalars Moriond 2007
Moriond 2007 Backup slides
The Worries • ‘Technical Naturalness’ • Runaway Behaviour • Stabilizing the Extra Dimensions • Famous No-Go Arguments • Problems with Cosmology • Constraints on Light Scalars Moriond 2007
The Worries Albrecht, CB, Ravndal, Skordis Tolley, CB, Hoover & Aghababaie Tolley, CB, de Rham & Hoover • ‘Technical Naturalness’ • Most brane properties and initial conditions do not lead to anything like • Runaway Behaviour the universe we see around us. • For many choices the extra dimensions • Stabilizing the Extra Dimensions implode or expand to infinite size. • Famous No-Go Arguments • Problems with Cosmology • Constraints on Light Scalars Moriond 2007
The Worries Albrecht, CB, Ravndal, Skordis Tolley, CB, Hoover & Aghababaie Tolley, CB, de Rham & Hoover • ‘Technical Naturalness’ • Most brane properties and initial conditions do not lead to anything like • Runaway Behaviour the universe we see around us. • For many choices the extra dimensions • Stabilizing the Extra Dimensions implode or expand to infinite size. • Initial condition problem: much like • Famous No-Go Arguments the Hot Big Bang, possibly understood by reference to earlier epochs of cosmology (eg: inflation) • Problems with Cosmology • Constraints on Light Scalars Moriond 2007
The Worries • ‘Technical Naturalness’ • Runaway Behaviour • Stabilizing the Extra Dimensions • Famous No-Go Arguments • Problems with Cosmology • Constraints on Light Scalars Moriond 2007
The Worries Salam & Sezgin • ‘Technical Naturalness’ • Classical flat direction corresponding to combination of radius and dilaton: • Runaway Behaviour e φ r 2 = constant . • Stabilizing the Extra Dimensions • Loops lift this flat direction, and in so doing give dynamics to φ and r . • Famous No-Go Arguments • Problems with Cosmology • Constraints on Light Scalars Moriond 2007
Kantowski & Milton The Worries Albrecht, CB, Ravndal, Skordis CB & Hoover Ghilencea, Hoover, CB & Quevedo ⎛ ⎞ 1 • ‘Technical Naturalness’ = + + ⎜ ⎟ 2 V [ a b log( rM ) c log ( rM )] ⎝ 4 ⎠ r • Runaway Behaviour Potential domination when: ≈ ≈ V ' 0 if r M exp( a / b ) • Stabilizing the Extra Dimensions Canonical Variables: • Famous No-Go Arguments ( ) ∂ 2 r = 2 L M • Problems with Cosmology kin p 2 r = + φ + φ − λφ 2 V ( a b c ) exp[ ] • Constraints on Light Scalars Moriond 2007
The Worries Albrecht, CB, Ravndal, Skordis ⎛ ⎞ 1 • ‘Technical Naturalness’ = + + ⎜ ⎟ 2 V [ a b log( rM ) c log ( rM )] ⎝ 4 ⎠ r • Runaway Behaviour Potential domination when: ≈ ≈ V ' 0 if r M exp( a / b ) • Stabilizing the Extra Dimensions Hubble damping can allow Canonical Variables: potential domination for • Famous No-Go Arguments exponentially large r, even ( ) ∂ 2 r though r is not stabilized. = 2 L M • Problems with Cosmology kin p 2 r = + φ + φ − λφ 2 V ( a b c ) exp[ ] • Constraints on Light Scalars Moriond 2007
The Worries • ‘Technical Naturalness’ • Runaway Behaviour • Stabilizing the Extra Dimensions • Famous No-Go Arguments • Problems with Cosmology • Constraints on Light Scalars Moriond 2007
The Worries • ‘Technical Naturalness’ • Weinberg’s No-Go Theorem : • Runaway Behaviour Steven Weinberg has a general objection to self-tuning mechanisms for solving the cosmological constant problem that are • Stabilizing the Extra Dimensions based on scale invariance • Famous No-Go Arguments • Problems with Cosmology • Constraints on Light Scalars Moriond 2007
The Worries • ‘Technical Naturalness’ • Weinberg’s No-Go Theorem : • Runaway Behaviour Steven Weinberg has a general objection to self-tuning mechanisms for solving the cosmological constant problem that are • Stabilizing the Extra Dimensions based on scale invariance • Famous No-Go Arguments • Problems with Cosmology • Constraints on Light Scalars Moriond 2007
The Worries • ‘Technical Naturalness’ • Weinberg’s No-Go Theorem : • Runaway Behaviour Steven Weinberg has a general objection to self-tuning mechanisms for solving the cosmological constant problem that are • Stabilizing the Extra Dimensions based on scale invariance • Famous No-Go Arguments ≈ λ φ • Problems with Cosmology 4 • Constraints on Light Scalars Moriond 2007
The Worries • ‘Technical Naturalness’ • Nima’s No-Go Argument : • Runaway Behaviour One can have a vacuum energy μ 4 with μ greater than the cutoff, provided it is turned on adiabatically. • Stabilizing the Extra Dimensions So having extra dimensions with r ~ 1/ μ • Famous No-Go Arguments does not release one from having to find an intrinsically 4D mechanism. • Problems with Cosmology • Constraints on Light Scalars Moriond 2007
The Worries • ‘Technical Naturalness’ • Nima’s No-Go Argument : • Runaway Behaviour One can have a vacuum energy μ 4 with μ greater than the cutoff, provided it is turned on adiabatically. • Stabilizing the Extra Dimensions • Scale invariance precludes obtaining \mu So having extra dimensions with r ~ 1/ μ • Famous No-Go Arguments greater than the cutoff in an adiabatic way: does not release one from having to find an intrinsically 4D mechanism. λφ = μ e & φ ≈ μ 4 • Problems with Cosmology 2 4 V eff implies • Constraints on Light Scalars Moriond 2007
The Worries • ‘Technical Naturalness’ • Runaway Behaviour • Stabilizing the Extra Dimensions • Famous No-Go Arguments • Problems with Cosmology • Constraints on Light Scalars Moriond 2007
The Worries • ‘Technical Naturalness’ • Post BBN : • Runaway Behaviour Since r controls Newton’s constant, its motion between BBN and now will cause unacceptably large changes to G . • Stabilizing the Extra Dimensions • Famous No-Go Arguments • Problems with Cosmology • Constraints on Light Scalars Moriond 2007
The Worries • ‘Technical Naturalness’ • Post BBN : • Runaway Behaviour Since r controls Newton’s constant, its motion between BBN and now will cause unacceptably large changes to G . • Stabilizing the Extra Dimensions Even if the kinetic energy associated with r • Famous No-Go Arguments were to be as large as possible at BBN, Hubble damping keeps it from rolling dangerously far between then and now. • Problems with Cosmology • Constraints on Light Scalars Moriond 2007
The Worries • ‘Technical Naturalness’ • Post BBN : • Runaway Behaviour Since r controls Newton’s constant, its motion between BBN and now will cause unacceptably large changes to G . • Stabilizing the Extra Dimensions Even if the kinetic energy associated with r • Famous No-Go Arguments were to be as large as possible at BBN, Hubble damping keeps it from rolling dangerously far between then and now. • Problems with Cosmology • Constraints on Light Scalars log r vs log a Moriond 2007
The Worries • ‘Technical Naturalness’ • Pre BBN : • Runaway Behaviour There are strong bounds on KK modes in models with large extra dimensions from: * their later decays into photons; • Stabilizing the Extra Dimensions * their over-closing the Universe; * their light decay products being too • Famous No-Go Arguments abundant at BBN • Problems with Cosmology • Constraints on Light Scalars Moriond 2007
The Worries • ‘Technical Naturalness’ • Pre BBN : • Runaway Behaviour There are strong bounds on KK modes in models with large extra dimensions from: * their later decays into photons; • Stabilizing the Extra Dimensions * their over-closing the Universe; * their light decay products being too • Famous No-Go Arguments abundant at BBN • Problems with Cosmology Photon bounds can be evaded by having invisible channels; others are model dependent, but eventually must be addressed • Constraints on Light Scalars Moriond 2007
The Worries • ‘Technical Naturalness’ • Runaway Behaviour • Stabilizing the Extra Dimensions • Famous No-Go Arguments • Problems with Cosmology • Constraints on Light Scalars Moriond 2007
The Worries • ‘Technical Naturalness’ • A light scalar with mass m ~ H has several generic difficulties : • Runaway Behaviour What protects such a small mass from large quantum corrections? • Stabilizing the Extra Dimensions • Famous No-Go Arguments • Problems with Cosmology • Constraints on Light Scalars Moriond 2007
The Worries • ‘Technical Naturalness’ • A light scalar with mass m ~ H has several generic difficulties : • Runaway Behaviour What protects such a small mass from large quantum corrections? • Stabilizing the Extra Dimensions • Famous No-Go Arguments Given a potential of the form V(r) = c 0 M 4 + c 1 M 2 /r 2 + c 2 /r 4 + … • Problems with Cosmology then c 0 = c 1 = 0 ensures both small mass and small dark energy. • Constraints on Light Scalars Moriond 2007
The Worries • ‘Technical Naturalness’ • A light scalar with mass m ~ H has several generic difficulties : • Runaway Behaviour Isn’t such a light scalar already ruled out by precision tests of GR in the solar system? • Stabilizing the Extra Dimensions • Famous No-Go Arguments • Problems with Cosmology • Constraints on Light Scalars Moriond 2007
The Worries • ‘Technical Naturalness’ • A light scalar with mass m ~ H has several generic difficulties : • Runaway Behaviour Isn’t such a light scalar already ruled out by precision tests of GR in the solar system? • Stabilizing the Extra Dimensions • Famous No-Go Arguments The same logarithmic corrections which enter the potential can also appear in its matter couplings, making them field dependent and so • Problems with Cosmology also time-dependent as φ rolls. Can arrange these to be small here & now. • Constraints on Light Scalars Moriond 2007
The Worries • ‘Technical Naturalness’ • A light scalar with mass m ~ H has several generic difficulties : • Runaway Behaviour Isn’t such a light scalar already ruled out by precision tests of GR in the solar system? • Stabilizing the Extra Dimensions α < 0 . 03 • Famous No-Go Arguments The same logarithmic corrections which enter the potential can also appear in its matter couplings, making them field dependent and so • Problems with Cosmology also time-dependent as φ rolls. Can arrange these to be small here & now. • Constraints on Light Scalars α vs log a Moriond 2007
The Worries • ‘Technical Naturalness’ • A light scalar with mass m ~ H has several generic difficulties : • Runaway Behaviour Shouldn’t there be strong bounds due to energy losses from red giant stars and • Stabilizing the Extra Dimensions supernovae? (Really a bound on LEDs and not on scalars.) • Famous No-Go Arguments • Problems with Cosmology • Constraints on Light Scalars Moriond 2007
The Worries • ‘Technical Naturalness’ • A light scalar with mass m ~ H has several generic difficulties : • Runaway Behaviour Shouldn’t there be strong bounds due to energy losses from red giant stars and • Stabilizing the Extra Dimensions supernovae? (Really a bound on LEDs and not on scalars.) • Famous No-Go Arguments Yes, and this is how the scale M ~ 10 TeV for gravity in the extra dimensions is obtained. • Problems with Cosmology • Constraints on Light Scalars Moriond 2007
Observational Consequences • Quintessence cosmology • Modifications to gravity • Collider physics • Neutrino physics • Astrophysics Moriond 2007
Observational Consequences Albrecht, CB, Ravndal & Skordis Kainulainen & Sunhede • Quintessence cosmology • Quantum vacuum energy lifts flat direction. • Specific types of scalar • Modifications to gravity interactions are predicted. • Collider physics • Includes the Albrecht- Skordis type of potential • Neutrino physics • Preliminary studies indicate it is possible to have viable cosmology: • Astrophysics • Changing G; BBN;… Moriond 2007
Observational Consequences Albrecht, CB, Ravndal & Skordis ⎛ ⎞ 1 = + + ⎜ ⎟ 2 V [ a b log( rM ) c log ( rM )] ⎝ 4 ⎠ • Quintessence cosmology • Quantum vacuum energy r lifts flat direction. Potential domination when: • Specific types of scalar • Modifications to gravity ≈ ≈ interactions are V ' 0 if r M exp( a / b ) predicted. • Collider physics • Includes the Albrecht- Canonical Variables: Skordis type of potential ( ) ∂ • Neutrino physics • Preliminary studies 2 r = 2 L M indicate it is possible to kin p 2 r have viable cosmology: • Astrophysics = + φ + φ − λφ • Changing G; BBN;… 2 V ( a b c ) exp[ ] Moriond 2007
Observational Consequences Albrecht, CB, Ravndal & Skordis Radiation • Quintessence cosmology • Quantum vacuum energy Matter lifts flat direction. Total Scalar • Specific types of scalar • Modifications to gravity interactions are predicted. • Collider physics • Includes the Albrecht- Skordis type of potential • Neutrino physics • Preliminary studies indicate it is possible to have viable cosmology: • Astrophysics • Changing G; BBN;… log ρ vs log a Moriond 2007
Observational Consequences Albrecht, CB, Ravndal & Skordis Ω Λ ~ 0.7 • Quintessence cosmology • Quantum vacuum energy lifts flat direction. Ω m ~ 0.25 • Specific types of scalar • Modifications to gravity interactions are Ω and w predicted. • Collider physics vs log a • Includes the Albrecht- Skordis type of potential Radiation • Neutrino physics • Preliminary studies Matter indicate it is possible to Total Scalar have viable cosmology: w Parameter: • Astrophysics w ~ – 0.9 • Changing G; BBN;… Moriond 2007
Observational Consequences Albrecht, CB, Ravndal & Skordis • Quintessence cosmology • Quantum vacuum energy lifts flat direction. • Specific types of scalar • Modifications to gravity interactions are predicted. • Collider physics α < • Includes the Albrecht- 0 . 03 Skordis type of potential • Neutrino physics • Preliminary studies indicate it is possible to have viable cosmology: • Astrophysics • Changing G; BBN;… α vs log a Moriond 2007
Observational Consequences Albrecht, CB, Ravndal & Skordis • Quintessence cosmology • Quantum vacuum energy lifts flat direction. • Specific types of scalar • Modifications to gravity interactions are predicted. • Collider physics • Includes the Albrecht- Skordis type of potential • Neutrino physics • Preliminary studies indicate it is possible to have viable cosmology: • Astrophysics • Changing G; BBN;… log r vs log a Moriond 2007
Observational Consequences • Quintessence cosmology • At small distances: • Changes Newton’s Law at range r/2 π ~ 1 μ m. • Modifications to gravity • At large distances • Scalar-tensor theory out • Collider physics to distances of order H 0 . • Neutrino physics • Astrophysics Moriond 2007
Observational Consequences • Quintessence cosmology • At small distances: • Changes Newton’s Law at range r/2 π ~ 1 μ m. • Modifications to gravity • At large distances • Scalar-tensor theory out • Collider physics to distances of order H 0 . • Neutrino physics • Astrophysics Moriond 2007
Observational Consequences • Quintessence cosmology • Not the MSSM! • No superpartners • Bulk scale bounded by • Modifications to gravity astrophysics • M g ~ 10 TeV • Collider physics • Many channels for losing energy to KK • Neutrino physics modes • Scalars, fermions, vectors live in the bulk • Astrophysics Moriond 2007
Observational Consequences • Quintessence cosmology • Can there be observable signals if M g ~ 10 TeV? M g • Modifications to gravity • Must hit new states before E ~ M g . Eg: string and KK M s states have M KK < M s < M g • Collider physics • Dimensionless couplings to bulk scalars are M KK • Neutrino physics unsuppressed by M g • Astrophysics Moriond 2007
Observational Consequences Azuelos, Beauchemin & CB ( ) ( = ∫ ) Φ 4 * • Quintessence cosmology S a d x H H x , y • Not the MSSM! b • No superpartners • Bulk scale bounded by • Modifications to gravity Dimensionless coupling! astrophysics O(0.1-0.001) from loops • M g ~ 10 TeV • Collider physics • Many channels for losing energy to KK • Neutrino physics modes • Scalars, fermions, vectors live in the bulk • Astrophysics Moriond 2007
Observational Consequences Azuelos, Beauchemin & CB ( ) ( = ∫ ) Φ 4 * • Quintessence cosmology S a d x H H x , y • Not the MSSM! b • No superpartners • Bulk scale bounded by • Modifications to gravity Dimensionless coupling! astrophysics O(0.1-0.001) from loops • M g ~ 10 TeV • Collider physics • Many channels for • Use H decay into γγ , losing energy to KK so search for two • Neutrino physics modes hard photons plus • Scalars, fermions, missing E T . vectors live in the bulk • Astrophysics Moriond 2007
Observational Consequences Azuelos, Beauchemin & CB • Quintessence cosmology • Not the MSSM! • No superpartners • Bulk scale bounded by • Modifications to gravity astrophysics • M g ~ 10 TeV • Collider physics • Many channels for losing energy to KK • Neutrino physics modes • Scalars, fermions, vectors live in the bulk • Astrophysics • Standard Model backgrounds Moriond 2007
Observational Consequences Azuelos, Beauchemin & CB • Quintessence cosmology • Not the MSSM! • No superpartners • Bulk scale bounded by • Modifications to gravity astrophysics • M g ~ 10 TeV • Collider physics • Many channels for losing energy to KK • Neutrino physics modes • Scalars, fermions, vectors live in the bulk • Astrophysics Moriond 2007
Observational Consequences Azuelos, Beauchemin & CB • Quintessence cosmology • Not the MSSM! • No superpartners • Bulk scale bounded by • Modifications to gravity astrophysics • M g ~ 10 TeV • Collider physics • Many channels for losing energy to KK • Neutrino physics modes • Scalars, fermions, vectors live in the bulk • Astrophysics • Significance of signal vs cut on missing E T Moriond 2007
Observational Consequences Azuelos, Beauchemin & CB • Quintessence cosmology • Not the MSSM! • No superpartners • Bulk scale bounded by • Modifications to gravity astrophysics • M g ~ 10 TeV • Collider physics • Many channels for losing energy to KK • Neutrino physics modes • Scalars, fermions, • Possibility of missing-E T cut improves the reach vectors live in the bulk • Astrophysics of the search for Higgs through its γγ channel Moriond 2007
Observational Consequences Matias, CB • Quintessence cosmology • SLED predicts there are 6D massless fermions in the bulk, as well as their • Modifications to gravity properties • Massless, chiral, etc. • Collider physics • Masses and mixings can be chosen to agree with oscillation data. • Neutrino physics • Most difficult: bounds on resonant SN oscillilations. • Astrophysics Moriond 2007
Observational Consequences Matias, CB • 6D supergravities have many bulk fermions: • Quintessence cosmology • SLED predicts there are • Gravity: (g mn , ψ m , B mn , χ , ϕ ) 6D massless fermions in • Gauge: (A m , λ ) the bulk, as well as their • Modifications to gravity properties • Hyper: ( Φ , ξ ) • Massless, chiral, etc. • Bulk couplings dictated by supersymmetry • Collider physics • Masses and mixings can • In particular: 6D fermion masses must vanish be naturally achieved • Back-reaction removes KK zero modes which agree with data! • Neutrino physics • Sterile bounds; • eg: boundary condition due to conical defect at oscillation experiments; brane position • Astrophysics Moriond 2007
Observational Consequences Matias, CB ( ) ( ) ∫ = λ 4 i • Quintessence cosmology S d x L H N x , y • SLED predicts there are u a i au b 6D massless fermions in the bulk, as well as their • Modifications to gravity Dimensionful coupling properties λ ~ 1/M g • Massless, chiral, etc. • Collider physics • Masses and mixings can be naturally achieved which agree with data! • Neutrino physics • Sterile bounds; oscillation experiments; • Astrophysics Moriond 2007
Observational Consequences Matias, CB ( ) ( ) ∫ = λ 4 i • Quintessence cosmology S d x L H N x , y • SLED predicts there are u a i au b 6D massless fermions in the bulk, as well as their SUSY keeps N massless in bulk; • Modifications to gravity Dimensionful coupling properties Natural mixing with Goldstino on branes; λ ~ 1/M g • Massless, chiral, etc. • Collider physics Chirality in extra dimensions provides natural L; • Masses and mixings can be naturally achieved which agree with data! • Neutrino physics • Sterile bounds; oscillation experiments; • Astrophysics Moriond 2007
Observational Consequences Matias, CB ( ) ( ) ∫ = λ 4 i • Quintessence cosmology S d x L H N x , y • SLED predicts there are u a i au b 6D massless fermions in the bulk, as well as their • Modifications to gravity Dimensionful coupling! properties ⎛ + − ⎞ λ λ L 0 0 0 v v λ ~ 1/M g ⎜ ⎟ e e • Massless, chiral, etc. λ + λ − ⎜ ⎟ L 0 0 0 v v • Collider physics μ μ • Masses and mixings can ⎜ ⎟ + − λ λ L 1 v v 0 0 0 ⎜ ⎟ be naturally achieved = τ τ M π λ + λ + λ + ⎜ ⎟ L 0 2 c r v v v which agree with data! • Neutrino physics μ τ 1 e ⎜ ⎟ π − − − λ λ λ L • Sterile bounds; 2 c 0 v v v ⎜ ⎟ μ τ 1 e ⎜ ⎟ oscillation experiments; M M O M M M • Astrophysics ⎝ ⎠ Moriond 2007
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