Shedding Light on the Hidden Sector

Transcription

1 Shedding Light on the Hidden Sector Particle Physics with Low-Energy Photons Andreas Ringwald DESY Theorieseminar, DESY, 25 June 2009, Zeuthen, D

2 Shedding Light on the Hidden Sector 1 1. Introduction Hints for new particles beyond standard model: Dark matter: WIMP or WISP? Dark energy: ultralight cosmon? Unification of forces: heavy superpartners? Strong CP problem: ultralight axion?

3 Shedding Light on the Hidden Sector 2 1. Introduction Hints for new particles beyond standard model: Dark matter: WIMP or WISP? Dark energy: ultralight cosmon? Unification of forces: heavy superpartners? Strong CP problem: ultralight axion? 1/α i Unification of the Coupling Constants in the SM and the minimal MSSM log Q 1/α i /α 1 1/α 2 1/α 3 MSSM [Amaldi, de Boer, Fürstenau 91] log Q

4 Shedding Light on the Hidden Sector 3 1. Introduction Hints for new particles beyond standard model: Dark matter: WIMP or WISP? Dark energy: ultralight cosmon? Unification of forces: heavy superpartners? Strong CP problem: ultralight axion? a g g

5 Shedding Light on the Hidden Sector 4 1. Introduction Hints for new particles beyond standard model: Dark matter: WIMP or WISP? Dark energy: ultralight cosmon? Unification of forces: heavy superpartners? Strong CP problem: ultralight axion? [Roszkowski]

6 Shedding Light on the Hidden Sector 5 Physics at the Terascale: The Large Hadron Collider (LHC) has a huge discovery potential for WIMPs Physics at the Milliscale: Experiments exploiting lowenergy photons and/or large electromagnetic fields have considerable discovery potential for WISPs

7 Shedding Light on the Hidden Sector 6 Physics at the Terascale: The Large Hadron Collider (LHC) has a huge discovery potential for WIMPs Physics at the Milliscale: Experiments exploiting lowenergy photons and/or large electromagnetic fields have considerable discovery potential for WISPs

8 Shedding Light on the Hidden Sector 7 Outline: 2. Axions and Axion-Like Particles 3. Ultralight Hidden-Sector Particles 4. Light Shining Through a Wall 5. Conclusions

9 Shedding Light on the Hidden Sector 8 2. Axions and Axion-Like Particles Strong CP problem: Due to non-abelian nature of QCD, additional CP-violating term in the Lagrangian, L CP viol. = α s 4π θ trg µν G µν α s 4π θ 1 2 ǫµναβ trg µν G αβ Effective CP-violating parameter in standard model, θ θ = θ + arg det M Upper bound on electric dipole moment of neutron θ Unnaturally small!

10 Shedding Light on the Hidden Sector 9 Peccei-Quinn solution to the strong CP problem: Introduce global anomalous chiral U(1) PQ symmetry, spontaneously broken by the vev of a complex scalar Φ = f a e ia/f a [Peccei,Quinn 77] Axion field a shifts under a U(1) PQ transformation, a a + const. Low-energy effective Lagrangian: L a = 1 2 µa µ a + L int a [ ] µ a ; ψ f a + rα s 4πf a atrg µν G µν + sα 8πf a a F µν F µν +... θ-term in L SM +L a can be eliminated by exploiting the shift symmetry, a a θf a /r Topological charge density trg µν Gµν 0 provides nontrivial potential for axion field axion is pseudo-nambu-goldstone boson [S.Weinberg 78; Wilczek 78]

11 Shedding Light on the Hidden Sector Mass obtained via chiral perturbation theory: [S.Weinberg 78] m a = r m πf π f a mu m d m u + m d 0.6 mev For large f a : axion is ultralight and invisible: e.g. coupling to photons, ( ) GeV f a /r [J.E. Kim 79; Shifman et al. 80; Dine et al. 81;...] L aγγ = 1 4 g a F µν F µν = g a E B, with [Bardeen,Tye 78; Kaplan 85; Srednicki 85] g = rα 2πf a ( 2 3 m u + 4m d s ) m u + m d r ( 13 GeV 1 ) GeV f a /r

12 Shedding Light on the Hidden Sector 11 Generic prediction for axion:

13 Shedding Light on the Hidden Sector 12 Axions in string theory: Axions with global anomalous PQ symmetries generic in string compactifications [Svrcek,Witten 06] Model-independent axion of weakly coupled heterotic string: dual of B µν, with µ and ν tangent to 4d Minkowski spacetime: f a = g 2 s 2πV6 M 2 s 16 GeV = α CM P 2π 2 Heterotic string: d low-energy Lagrangian: L d = 2πM8 s g 2 s gr M 6 s 2πg 2 s 1 4 trf F 2πM4 s g 2 s Compactify 6 extra dimensions: L 4d = M2 P 2 gr 1 4g 2 YM Read off coefficients: gtrf µνf µν 1 f 2 a 1 2 H H H H+... m a 9 ev MP 2 = 4π gs 2 Ms 8 V 6 ; g2 YM = 4πg2 s Ms 6V ; fa 2 = gs 2 6 2πMs 4V 6 Large M s = α YM /(4π) M P

14 Shedding Light on the Hidden Sector 13 Axions in string theory: Axions with global anomalous PQ symmetries generic in string compactifications [Svrcek,Witten 06] Axions in intersecting D-brane models in type II string theory come from zero modes of the RR gauge fields C Intersecting D-brane models: Gauge theory lives on D(3 + q)- branes, extending along the 4 noncompact dimensions and wrapping a q-cycle in the extra dimensions f a M s wider range of possibilities Plenitude of zero modes axion-like particles Stückelberg axions associated with anomalous U(1)s [Coriano,Irges,Kiritsis 06] SM Gravity lives in all dimensions Smaller string scale because of large volume, M s g s M P / V 6 M 6 s ; can be as low as TeV HS

15 Shedding Light on the Hidden Sector 14 Constraints on coupling of axion-like particles (ALPs) to photons: [Raffelt;...] HB stars Galactic dark matter Photon regeneration due to ALP-γ oscillations (light shining through a wall; CERN Axion Solar Telescope (CAST); galactic dark matter search); energy loss (lifetime of Helium Burning (HB) stars)

16 Shedding Light on the Hidden Sector Ultralight Hidden-Sector Particles Extensions of standard model based on supergravity or superstrings predict hidden sector of particles which are very weakly coupled to the visible sector standard model particles; cf. gravity mediation of SUSY breaking Sector hidden mediators heavy and/or very weakly coupled Possible WISPs: hidden sector U(1) gauge bosons ( hidden photons γ ) and hidden sector particles charged under the hidden U(1) ( mini-charged particles (MCPs)) More models with ultralight hidden U(1)s: mirror world or extreme, 32 copies of SM [Foot,...;Dvali,...]

17 Shedding Light on the Hidden Sector 16 U(1) factors in hidden sectors: generic prediction of realistic string compactifications E 8 E 8 heterotic closed string theory IIA/IIB open string theory with branes Orbifold compactifications of heterotic string theory: e.g. [Buchmüller et al. 07;... ] E 8 E 8 G SM U(1) 4 [SU(4) SU(2) U(1) 4] Some hidden U(1) gauge bosons and hidden charged fermions may remain massless or light Dominant interaction with standard model: gauge kinetic mixing and minicharge or [Lebedev et al. 07] E 8 E 8 G SM U(1) 4 [SO(8) SU(2) U(1) 3] and many more

18 Shedding Light on the Hidden Sector 17 U(1) factors in hidden sectors: generic prediction of realistic string compactifications E 8 E 8 heterotic closed string theory IIA/IIB open string theory with branes Some hidden U(1) gauge bosons and hidden charged fermions may remain massless or light Compactification of type II string theory: Hidden Sectors CY 3 M 4 Q L U(2) e L Dominant interaction with standard model: gauge kinetic mixing and minicharge U(3) Q R U(1) e R U(1) [..,Conlon,Quevedo,..] Visible Sector (SM)

19 Shedding Light on the Hidden Sector 18 U(1) factors in hidden sectors: generic prediction of realistic string compactifications E 8 E 8 heterotic closed string theory IIA/IIB open string theory with branes Some hidden U(1) gauge bosons and hidden charged fermions may remain massless or light Dominant interaction with standard model: gauge kinetic mixing and minicharge (for Chern-Simons like coupling: Low-energy effective Lagrangian: [Holdom 85] L = 1 4 Fµν Fµν 1 }{{} 4 Bµν Bµν + 1 }{{} 2 χ Fµν Bµν }{{} U(1) v U(1) h kin mix + v(i / + ea/)v + h(i / + e }{{} h B/)h +... }{{} v matter h matter Dimensionless kinetic mixing parameter χ: Kinetic mixing generically appears in theories with several U(1) factors (renormalizable term respecting gauge and Lorentz symmetry) Integrating out heavy messenger particles generically tends to generate χ 0: Diagonalization of kinetic term, B µ B µ +χa µ ; Hidden sector charged particle gets induced electric charge: e h hb/ h eh h B/ h + χeh ha/ h A. Ringwald [Antoniadis,Boyarski,Ruchayski]) (DESY) Zeuthen, June 2009 Q vis h ǫe = χe h

20 Shedding Light on the Hidden Sector 19 U(1) factors in hidden sectors: generic prediction of realistic string compactifications KM in heterotic string models: [Dienes,Kolda,March-Russell 97] E 8 E 8 heterotic closed string theory IIA/IIB open string theory with branes Some hidden U(1) gauge bosons and hidden charged fermions may remain massless or light µ Va χ ee h 16π 2 C m M P ν Vb Dominant interaction with standard model: gauge kinetic mixing and minicharge > 17, for C >, m> 0 TeV

21 Shedding Light on the Hidden Sector 20 U(1) factors in hidden sectors: generic prediction of realistic string compactifications E 8 E 8 heterotic closed string theory IIA/IIB open string theory with branes KM in IIA/IIB string models: [Lüst,Stieberger 03;Abel,Schofield 04;Berg,Haack,Körs 05] Some hidden U(1) gauge bosons and hidden charged fermions may remain massless or light Dominant interaction with standard model: gauge kinetic mixing and minicharge e.g. mixing with U(1) residing on D7 brane wrapping LARGE 4-cycle χ ee h 16π 2 g s 8π (V 6M 6 s) 1/3 > 12, for V 6 M 6 s < 30 (i.e. M s > TeV) [Goodsell,Jaeckel,Redondo,AR 09]

22 Shedding Light on the Hidden Sector 21 The rich phenomenology of hidden U(1)s: [Bartlett,.. 88; Kumar,.. 06; Ahlers,.. 07; Jaeckel,.. 07; Redondo,.. 08;Postma,Redondo 08;Bjorken,Essig,Schuster,Toro 09;...] Log Χ Jupiter Earth CMB Coulomb FIRAS hcmb LSW CAST Rydberg Solar Lifetime a e,μ 3 E774 E141 E137 EW HB Log m Γ' ev Deviations from 1/r 2 (Jupiter,Coulomb); γ γ oscillations (CMB,Light Shining through a Wall (LSW); stellar evolution (Sun,HB,dDM); fixed target; e + e (Υ,EW) 15

23 Shedding Light on the Hidden Sector 22 The rich phenomenology of hidden U(1)s: [Jaeckel,Redondo,AR 08;Arkani-Hamed,.. 08;Ibarra,AR,Weniger 08;...] Log Χ Jupiter Earth SUSY DM CMB Coulomb FIRAS hcmb LSW CAST N Ν CMB 3 Rydberg Solar Lifetime HB ddm a e,μ 3 E774 E141 E137 DAMA EW LHC Log m Γ' ev Deviations from 1/r 2 (Jupiter,Coulomb); γ γ oscillations (CMB,Light Shining through a Wall (LSW), stellar evolution (Sun,HB), ddm); Z γ mixing (EW) 15

24 Shedding Light on the Hidden Sector 23 The rich phenomenology of hidden U(1)s: [Ahlers,.. 07;Jaeckel,AR 07;Gninenko,Redondo 08;...] Log Χ Jupiter Earth SUSY DM CMB Coulomb FIRAS hcmb MW cavity LSW CAST LSW SHIPS Rydberg Solar Lifetime HB X ray SAT a e,μ 3 E774 E137 EW Fixed Target E141 LHC Log m Γ' ev Deviations from 1/r 2 (Jupiter,Coulomb); γ γ oscillations (CMB,Light Shining through a Wall (LSW), stellar evolution (Sun,HB), ddm); Z γ mixing (EW) 15

25 Shedding Light on the Hidden Sector 24 Expectations in LARGE volume string compactifications (D7 brane wrapping LARGE 4-cycle): [Goodsell,Jaeckel,Redondo,AR in prep.]

26 Shedding Light on the Hidden Sector 25 The rich phenomenology of minicharged particles: [Davidson,.. 90;Gies,.. 06;Ahlers,.. 07;Melchiorri,.. 07] Energy loss (Red Giants, RF Cavity); cosmic expansion rate (BBN); deviations of black body spectrum (CMB); γ γ oscillations (LSW);...

27 Shedding Light on the Hidden Sector Light Shining through a Wall Linearly polarized laser beam in vacuum or along a transverse magnetic field LSW via photon-alp oscillations: Place wall in beam pipe: laser beam will be absorbed neutral WISPs (ALP, γ ) fly through wall and reconvert on other side of wall into photons, which can be detected [Okun 82;Sikivie 83;Anselm 85;..] γ laser φ B γ-γ oscillations: γ γ γ γ B γ laser Pioneering experiment: BFRT Several ongoing experiments

28 Shedding Light on the Hidden Sector Light Shining through a Wall Linearly polarized laser beam in vacuum or along a transverse magnetic field Place wall in beam pipe: laser beam will be absorbed neutral WISPs (ALP, γ ) fly through wall and reconvert on other side of wall into photons, which can be detected [Okun 82;Sikivie 83;Anselm 85;..] Pioneering experiment: BFRT Several ongoing experiments Photon-WISP evolution along distance L: i d ( γ dl φ ) = 1 ( 0 δ 2ω δ m 2 φ 87;Ahlers,Gies,Jaeckel,Redondo,AR 07] ) ( γ φ ) [Okun 82;Stodolsky,Raffelt WISP δ δ m 2 φ ALP (0 ) g B ext ω 0 m 2 φ [ ALP (0 + ) 0 g + B ext ω m 2 φ + [ HP χm 2 γ χm 2 γ m 2 γ MCP+HP 2χω 2 N 2χω 2 N 2ω 2 N, [ Transition probability: P(γ φ) 4δ2 m 4 φ sin 2 m2 φ L 4ω

29 Shedding Light on the Hidden Sector Light Shining through a Wall Linearly polarized laser beam in vacuum or along a transverse magnetic field Place wall in beam pipe: laser beam will be absorbed neutral WISPs (ALP, γ ) fly through wall and reconvert on other side of wall into photons, which can be detected [Okun 82;Sikivie 83;Anselm 85;..] Pioneering experiment: BFRT Several ongoing experiments Experiment Laser < P > Magnets ALPS 532 nm; FP W BFRT 500 nm; DL 0 W BMV 64 nm; LULI 8 21 γ/pulse GammeV 532 nm; 3.2 W LIPSS 900 nm; FEL 300 W OSQAR 64 nm; FP > 1 kw B 1 = B 2 = 5 T l 1 = l 2 = 4.21 m B 1 = B 2 = 3.7 T l 1 = l 2 = 4.4 m B 1 = B 2 = 11 T l 1 = l 2 = 0.25 m B 1 = B 2 = 5 T l 1 = l 2 = 3 m B 1 = B 2 = 1.7 T l 1 = l 2 = 1 m B 1 = B 2 = 9.5 T l 1 = l 2 = 14 m

30 Shedding Light on the Hidden Sector Light Shining through a Wall Linearly polarized laser beam in vacuum or along a transverse magnetic field ALPS (Any-Light Particle Search): [AEI, DESY, Hamburger Sternwarte, Laser Zentrum Hannover] Place wall in beam pipe: laser beam will be absorbed neutral WISPs (ALP, γ ) fly through wall and reconvert on other side of wall into photons, which can be detected [Okun 82;Sikivie 83;Anselm 85;..] γ laser φ γ laser Pioneering experiment: BFRT Several ongoing experiments B B

31 Shedding Light on the Hidden Sector Light Shining through a Wall Linearly polarized laser beam in vacuum or along a transverse magnetic field Place wall in beam pipe: laser beam will be absorbed neutral WISPs (ALP, γ ) fly through wall and reconvert on other side of wall into photons, which can be detected [Okun 82;Sikivie 83;Anselm 85;..] Pioneering experiment: BFRT Several ongoing experiments ALPS (Any-Light Particle Search): [AEI, DESY, Hamburger Sternwarte, Laser Zentrum Hannover] Primary beam: enhanced LIGO laser (64 nm, 35 W cw) frequency doubled to 532 nm 0 fold power build up through resonant optical cavity (Fabry-Perot), µm focus CCD camera: expect regenerated photons in signal region of a few pixel

32 Shedding Light on the Hidden Sector Light Shining through a Wall Linearly polarized laser beam in vacuum or along a transverse magnetic field Limits from ALPS run in 12/2008 and prospects for 7/2009: Place wall in beam pipe: laser beam will be absorbed neutral WISPs (γ, ALP) fly through wall and reconvert on other side of wall into photons, which can be detected [Okun 82;Sikivie 83;Anselm 85;..] Pioneering experiment: BFRT Several ongoing experiments [ALPS Collaboration 09]

33 Shedding Light on the Hidden Sector Light Shining through a Wall Linearly polarized laser beam in vacuum or along a transverse magnetic field Limits from ALPS run in 12/2008 and prospects for 7/2009: Place wall in beam pipe: laser beam will be absorbed neutral WISPs (γ, ALP) fly through wall and reconvert on other side of wall into photons, which can be detected [Okun 82;Sikivie 83;Anselm 85;..] Pioneering experiment: BFRT Several ongoing experiments [ALPS Collaboration 09]

34 Shedding Light on the Hidden Sector Light Shining through a Wall Linearly polarized laser beam in vacuum or along a transverse magnetic field Limits from ALPS run in 12/2008 and prospects for 7/2009: Place wall in beam pipe: laser beam will be absorbed neutral WISPs (γ, ALP) fly through wall and reconvert on other side of wall into photons, which can be detected [Okun 82;Sikivie 83;Anselm 85;..] Pioneering experiment: BFRT Several ongoing experiments [ALPS Collaboration 09]

35 Shedding Light on the Hidden Sector Light Shining through a Wall Linearly polarized laser beam in vacuum or along a transverse magnetic field Limits from ALPS run in 12/2008 and prospects for 7/2009: Place wall in beam pipe: laser beam will be absorbed neutral WISPs (γ, ALP) fly through wall and reconvert on other side of wall into photons, which can be detected [Okun 82;Sikivie 83;Anselm 85;..] Pioneering experiment: BFRT Several ongoing experiments [ALPS Collaboration 09]

36 Shedding Light on the Hidden Sector Light Shining through a Wall Linearly polarized laser beam in vacuum or along a transverse magnetic field Place wall in beam pipe: laser beam will be absorbed neutral WISPs (γ, ALP) fly through wall and reconvert on other side of wall into photons, which can be detected [Okun 82;Sikivie 83;Anselm 85;..] Pioneering experiment: BFRT Roadmap of ALP search with LSW: ] -1 g [GeV state-of-the-art (ALPS) log (m [ev]) [A. Lindner 09] astrophysics QCD axion Several ongoing experiments

37 Shedding Light on the Hidden Sector Light Shining through a Wall Linearly polarized laser beam in vacuum or along a transverse magnetic field Place wall in beam pipe: laser beam will be absorbed neutral WISPs (γ, ALP) fly through wall and reconvert on other side of wall into photons, which can be detected [Okun 82;Sikivie 83;Anselm 85;..] Pioneering experiment: BFRT Roadmap of ALP search with LSW: ] -1 g [GeV state-of-the-art (ALPS) log (m [ev]) [A. Lindner 09] ALPS with 4+4 LHC dipoles astrophysics QCD axion Several ongoing experiments

38 Shedding Light on the Hidden Sector Light Shining through a Wall Linearly polarized laser beam in vacuum or along a transverse magnetic field Place wall in beam pipe: laser beam will be absorbed neutral WISPs (γ, ALP) fly through wall and reconvert on other side of wall into photons, which can be detected [Okun 82;Sikivie 83;Anselm 85;..] Pioneering experiment: BFRT Roadmap of ALP search with LSW: ] -1 g [GeV state-of-the-art (ALPS) log (m [ev]) [A. Lindner 09] ALPS with 4+4 LHC dipoles 4+4 LHC dipoles, new laser & detector astrophysics QCD axion Several ongoing experiments

39 Shedding Light on the Hidden Sector Light Shining through a Wall Linearly polarized laser beam in vacuum or along a transverse magnetic field Place wall in beam pipe: laser beam will be absorbed neutral WISPs (γ, ALP) fly through wall and reconvert on other side of wall into photons, which can be detected [Okun 82;Sikivie 83;Anselm 85;..] Pioneering experiment: BFRT Roadmap of ALP search with LSW: ] -1 g [GeV state-of-the-art (ALPS) log (m [ev]) [A. Lindner 09] ALPS with 4+4 LHC dipoles 4+4 LHC dipoles, new laser & detector 4+4 LHC dipoles, new laser & detector, 2nd cavity astrophysics QCD axion Several ongoing experiments

40 Shedding Light on the Hidden Sector Light Shining through a Wall Linearly polarized laser beam in vacuum or along a transverse magnetic field Second Fabry-Perot Cavity: [Hoogeveen,Ziegenhagen 91;Sikivie,Tanner,van Bibber 07] Place wall in beam pipe: laser beam will be absorbed neutral WISPs (ALP, γ ) fly through wall and reconvert on other side of wall into photons, which can be detected [Okun 82;Sikivie 83;Anselm 85;..] (a) Laser (b) IO Laser B 0 a Magnet L Wall B 0 Magnet L Photon Detector Photon Detectors Pioneering experiment: BFRT Several ongoing experiments Magnet Matched Fabry-Perots Magnet

41 Shedding Light on the Hidden Sector Light Shining through a Wall Linearly polarized laser beam in vacuum or along a transverse magnetic field XFEL or synchrotron light through wall suffers from low photon flux [Rabadan,AR,Sigurdson 06;Dias,Lugones 09] Place wall in beam pipe: laser beam will be absorbed neutral WISPs (ALP, γ ) fly through wall and reconvert on other side of wall into photons, which can be detected [Okun 82;Sikivie 83;Anselm 85;..] Pioneering experiment: BFRT Several ongoing experiments

42 Shedding Light on the Hidden Sector Light Shining through a Wall Linearly polarized laser beam in vacuum or along a transverse magnetic field Roadmap of HP search with LSW: Place wall in beam pipe: laser beam will be absorbed neutral WISPs (γ, ALP) fly through wall and reconvert on other side of wall into photons, which can be detected [Okun 82;Sikivie 83;Anselm 85;..] Pioneering experiment: BFRT Several ongoing experiments [Redondo 09]

43 Shedding Light on the Hidden Sector 42 Helioscope Search for Hidden Photons [Redondo 08; Gninenko,Redondo 08;...] Sun produces huge flux of hidden photons, SHIPS (Solar Hidden Photon Search) at Hamburger Sternwarte: ( 32 χ 2 m ) γ 4 1 ev cm 2 s ev Hidden photons oscillate into real optical photons inside light-tight and evacuated tube, mounted on astronomical telescope to follow the sun Photons are collected by mirror onto sensitive photo-detector [Wiedemann 09]

44 Shedding Light on the Hidden Sector 43 Helioscope Search for Hidden Photons [Redondo 08; Gninenko,Redondo 08;...] Sun produces huge flux of hidden photons, SHIPS (Solar Hidden Photon Search) at Hamburger Sternwarte: ( 32 χ 2 m ) γ 4 1 ev cm 2 s ev Hidden photons oscillate into real optical photons inside light-tight and evacuated tube, mounted on astronomical telescope to follow the sun Photons are collected by mirror onto sensitive photo-detector [AR 09]

45 Shedding Light on the Hidden Sector 44 Helioscope Search for Hidden Photons [Redondo 08; Gninenko,Redondo 08;...] Sun produces huge flux of hidden photons, SHIPS (Solar Hidden Photon Search) at Hamburger Sternwarte: ( 32 χ 2 m ) γ 4 1 ev cm 2 s ev Hidden photons oscillate into real optical photons inside light-tight and evacuated tube, mounted on astronomical telescope to follow the sun Photons are collected by mirror onto sensitive photo-detector [Redondo 09]

46 Shedding Light on the Hidden Sector 45 Microwave Cavity Experiments High quality cavities can be exploited to search for γ ALPs [Jaeckel,AR 07;Caspers,Jaeckel,AR in prep.] Discovery potential: substantial reach in parameter space for γ may reach CAST s ALPs sensitivity with presently available technology [Jaeckel,AR 07] Yale: Experiment in progress

47 Shedding Light on the Hidden Sector 46 Microwave Cavity Experiments High quality cavities can be exploited to search for [Jaeckel,AR 07;Caspers,Jaeckel,AR in prep.] γ ALPs [Hoogeveen 92] Discovery potential: substantial reach in parameter space for γ may reach CAST s ALPs sensitivity with presently available technology [Jaeckel,AR 07] Yale: Experiment in progress

48 Shedding Light on the Hidden Sector 47 Microwave Cavity Experiments High quality cavities can be exploited to search for γ ALPs [Jaeckel,AR 07;Caspers,Jaeckel,AR in prep.] Discovery potential: substantial reach in parameter space for γ may reach g GeV 1 with presently available technology [Jaeckel,AR 07] Yale: Experiment in progress

49 Shedding Light on the Hidden Sector Conclusions A low-energy frontier is forming worldwide: Fundamental physics with low energy photons and spare parts from high-energy frontier accelerators These laboratory experiments have considerable discovery potential for ultralight particles beyond the standard model, which appear quite naturally in realistic string compactifications: axion-like particles hidden-sector U(1) gauge bosons hidden-sector fermions charged under these extra U(1)s Theoretical predictions of masses and couplings very uncertain any experimental hint or constraint extremely welcome!

50 Shedding Light on the Hidden Sector 49 In contrast to a WIMP: If a WISP is found, it may have immediate applications Hidden Laser Communications! [Jaeckel,Redondo,AR 09]