Axion Dark matter and detection John Hopkins Workshop Heidelberg, June 2014 Javier Redondo (LMU/MPP Munich) outline - Axions and strong CP - Axion CDM - Isocurvature problems - Detecting Axion CDM - Cavities - Dish antenna The strong CP “hint” and axions - U(1)A is color anomalous, CP-violating phase θ = θQCD + δ is physical LSM mu e 0 ∈ −¯ qL 0 iδ 0 md eiδ 0 ... u αs � ... d − GG θQCD 8π ... R ... Neutron EDM dn ∼ θ × O(10−2 )[e fm] dexp < 3 × 10−13 [e fm] n g JAµ ∂µ J5µ q g θ < 10−10 !! - why is soooo small? is there any fundamental reason? massless q? P,CP symmetries? - (not in SM) - set tree level - loop problems - still ~ok Axion a - New axial U(1) c.a. symmetry - spontaneously broken (PGB!) - θ promoted to field θ → a/fa - QCD potential V (θ) θ→0 eff θ Axion mass and couplings (and model dependencies) - Peccei-Quinn symmetry, color anomalous, spontaneously broken at fa ¯ ¯ L QR Φ + h.c) − λ|Φ|4 + µ2 |Φ|2 L = LSM + iQDQ − (y Q Φ(x) = ρ(x)e i a(x) fa (KSVZ model) - At energies below fa 1 αs � a 2 L ∈ (∂a) + GG 2 8π fa - At energies below ΛQCD , axion mass a − η � − π 0 − η − ... mixing mπ fπ 109 GeV ma � ∼ 6meV fa fa axion couplings La,I = � N a α µ µν a ¯ � cN,a N γ γ5 N + caγ Fµν F + ... fa 2π fa nucleons ... photons ... mesons ... Parameter spaces: generic fa �GeV� 2.0 1014 1013 1012 1011 1010 109 108 107 106 105 104 103 102 101 Hot�DM � CMB � BBN 1.5 Cold DM predictions 1.0 PreInflation�PQ 0.5 PostInflation�PQ SK Burst Duration ? �gae � ? SN1987A Globular Clusters �gaΓ � White Dwarfs �gae � Solar Neutrino flux �gaΓ � �gae � 0.0 ADMX ADMX�II IAXO Beam Dump Telescope CAST �0.5 ma �eV� 10�7 10�6 10�5 10�4 10�3 10�2 10�1 1 10 102 103 104 105 106 - Axions (if existing) are very light and very weakly interacting! -> WISP! Axion cold dark matter: vacuum alignment - Axions: small mass, small interactions, thermal DM time, 1/T - non-thermal DM, Initial conditions Domains=horizon Cosmic strings Damped oscillations=CDM θ=0 SSB QCD D. Walls strings Axion cold dark matter: vacuum alignment - Axions: small mass, small interactions, thermal DM SCENARIO-I - non-thermal DM, Initial conditions time, 1/T realignment+CS+DWs Domains=horizon Cosmic strings SSB O(1) inhomogeneous DM θ=0 QCD-horizon scale QCD miniclusters D.Walls Damped oscillations=CDM strings Axion cold dark matter: vacuum alignment - Axions: small mass, small interactions, thermal DM time, 1/T - non-thermal DM, Initial conditions Damped oscillations=CDM INFLATION!! SSB θ=0 QCD D. Walls strings Axion cold dark matter: vacuum alignment - Axions: small mass, small interactions, thermal DM SCENARIO-II - non-thermal DM, Initial conditions realignment only INFLATION!! SSB θ=0 QCD D. Walls time, 1/T Damped oscillations=CDM strings Rough relic abundance of axion Dark matter - Energy density redshifts as matter, from the onset of oscillations ρa (t) ∼ 2 4 θI ΛQCD � R1 R0 �3 � ∼ - today... ρa (t0 ) ∝ R1 R(t) � T0 T1 �3 ∼ �3 � T √ 0 H1 mPl �3 ∼ � T0 √ ma mPl �3 ∝ m−3/2 a - doing it properly... (thermal axion mass) 2 −3/2 θ I ma ρa (t0 ) ∝ 2 −7/6 θ I ma Axion DM abundance fitting the observations fa �GeV� 2.0 1014 1013 1012 1011 1010 109 108 107 Cold DM predictions 104 103 PreInflation�PQ ? PostInflation�PQ Excluded (too much DM 0.5 ADMX�II �gae � ? 102 101 IAXO SN1987A Globular Clusters �gaΓ � White Dwarfs �gae � Solar Neutrino flux �gaΓ � �gae � SCENARIO-I ADMX SK Burst Duration SCENARIO-II 0.0 105 Hot�DM � CMB � BBN 1.5 1.0 106 Beam Dump Telescope CAST �0.5 ma �eV� 10�7 10�6 10�5 10�4 10�3 10�2 10�1 1 10 102 103 104 105 106 The isocurvature problem after BICEP2 SCENARIO-II - Axion fluctuates during inflation (entropy perturbations) Piso HI2 HI2 d�na � d�a2 � = 2 2 = 2 2 2 = ∼ na a2I π aI π f a θI insisting on axion DM θI = θI (fa ) Constraint fa (HI ) , BICEP2 would exclude SC-II in the simplest models... of course, there are plenty of ways out ... f a � HI EXCLUDED Laboratory Experiments to detect axion DM - Dish antenna DM a photon to detect! B-field - Cavity experiments DM a amplify and detect B-field - Light propagation B E x - Oscillating EDM DM around us ρCDM GeV 1 2 2 2 � 0.3 = ma na � ma fa θ 3 cm 2 velocities in the galaxy phase space density θ ∼ O(10−19 ) v � 300 km/s ∼ 10−3 c � �4 µeV na 29 ∼ 10 4πp3 ma 3 occupation number is HUGE! a(t) = a0 cos(ma t) Roughly ... Fourier-transform still can treat it like a classical (NR) field ma v 2 δω = 2 a(x) ω � ma (1 + v 2 /2 + ...) δω ∼ 10−6 ω ω ma E-fields from axion CDM in a B-field α a LI = −caγγ B·E 2π fa - In a static magnetic field, the oscillating axion field generates EM-fields α LI = −caγγ θ(t) Bext · E 2π B-field - Electric fields of order |E| ∼ O(10−12 V /m)|Bext | cγ cos(ma t) - oscillating at a frequency given by the axion mass Do not depend on mass or coupling strength! Detecting EM fields from Axion Dark Matter - Haloscope (Sikivie 83) “Amplify resonantly the EM fields created by axionDM in a B-field in a cavity” (on resonance) ν[GHz] 10�1 1 103 103 RBF - Past experiments Florida U., RBF, ADMX, CARRACK - Future endeavors: ADMX, ADMX-HF, YMCE, CAPP - Noise Pnoise = Tsys ∆νa ∝ m2a - Signal/noise in ∆νa of time, t, 1 m2a S Pout � = ∆νa t N Pnoise c4γ 1 d∆ma - Scanning rate ∝ 9 ma dt ma ADMX DFSZ Scenario I 10�1 10�7 10�6 10 CARRACK? Pout ∝ V ma ∼ 1 ADMX cγ KSVZ UF ADMX-HF 102 10 Cylindrical cavity (h/r=b) like ADMX but scaled (V ∝ m−3 a ) IAXO 102 - Parameters unexplored at low and high masses: WHY? - Signal 102 10 ADMX2 P ∼ Q|Ea |2 (V ma )Gκ II 10�4 10�5 1 10�1 10�3 ma [µeV] Very easy, but needs large magnet volume! Very complicated, needs new ideas... DM searches with future IAXO (International Axion Observatory) field map of transverse cut - Length = 20 m Magnetised radius ~ 1 m Peak value ~ 5.4 T Average in bore 2.5 T Available T ~ 4.5 K (but warm bores in design) 2 x[m 1 y[m] 0 �1 �2 - Sensitivity �2 Big cavity (realistic) �1 0 x[m] 1 Many flat (exploit the huge volume) (very speculative, R&D needed!) 2 Simplest experiment: Dish antenna 2 −26 P ∼ |E| Adish ∼ 10 spherical reflecting dish Horns at al JCAP04(2013)016 � B cγ 5T 2 �2 Adish Watt 2 1m Simplest experiment: Dish antenna Ν�GHz� 1 ρCDM cΓ 0.3GeV ∼ cm3 1 102 ADMX�HF O(10^6) channels 10 KSVZ 1 DFSZ HS CARRACK 10�1 �2 ADMX�II 10 A=10m2, T=QL, B=10T, t=1year, ADMX A=10m2,T=5K, B=5T, t=1year, BFRT ADMX 102 102 10 HKS Post�Inflation�PQ DS Pre�Inflation�PQ 10�2 10 10�6 ma �eV� :-) broadband! 10�5 10�1 measure 1/octave of a decade with the same detector at the same time 10�4 10�3 δω ∼ O(1) ω Possible improvement Enhance the emissivity by multilayers of dielectric |Ea | → |Ea | × N Ν �GHz� 102 Increases sensitivity but losses bandwidth boostΧeff�Χ factor + back production and all reflexions ... 102 10 102 4 layers tuned lambda/2 10 10 1 1 10�1 10�2 10�5 10�1 10�4 ma �eV� 10�2 10�3 Dish antenna and miniclusters - Typical Dish antenna experiments fall a bit short, 3 if the DM density is just ρCDM = 0.3GeV/cm - 0.1-1 meV range is most interesting in Scenario-II 1 103 103 8-Dish IAXOQL 102 102 8-Dish IAXOSYS 10 - S-II predicts miniclusters of axion CDM Mmc ∼ 10−12 M⊙ Ωmc /ΩaCDM ∼ O(1) Zurek et al 07, See also Kolb & Tkachev 94 - Encounter with the Earth (every 104 years) ρCDM × 106 , Qa ∼ 109 , t ∼ 3days 102 10 cγ Scenario II 1 10�1 10�6 10�4 10�5 ma [eV] - Even with a modest realistic experiment one can get a huge signal ! (if lucky...) 10 1 10�1 10�3 Conclusions - Axion DM - well motivated and testable - but underrepresented (gets better) - key targets not covered - plenty of new ideas uncovered here - Cavity experiments on the run - micro-eV range by ADMX, ADMX-HF - lower masses, IAXO? - higher masses, new ideas! - Dish antenna - a little short for axions - broadband/miniclusters! - boost with dielectric layers! - good for ALPs, hidden photons! Getting better - New IBS (Institute of Basic Science) Center for Axion and Precision Physics (CAPP) KAIST campus, Daejeon/Korea - + in US - Yale developing ADMX-HF - CASPER - Europe getting involved - CASPER, Budker@Mainz - DESY, CERN, Unizar - International AXion Observatory main goal: solar axions but also DM
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