Solar Axions Globular Cluster Supernova 1987A Dark Matter Long-Range Force. Axion Landscape. Georg G. Raffelt, Max-Planck-Institut für Physik, München

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1 Solar Axions Globular Cluster Supernova 1987A Dark Matter Long-Range Force Axion Landscape Georg G. Raffelt, Max-Planck-Institut für Physik, München

2 High- and Low-Energy Frontiers in Particle Physics Cosmological constant QCD scale Electroweak scale GUT scale Planck mass ev m D 2 M m D Heavy right-handed neutrinos (see-saw mechanism) M WIMP dark matter (related to EW scale, perhaps SUSY) Axion dark matter (related to Peccei-Quinn symmetry) m a m πf π f a m π, f π f a

3 Bestiarium of Low-Mass Bosons Weakly Interacting Sub-eV Particles (WISPs) Axions (1 parameter family m a f a m π f π ) Solves strong CP problem Could be dark matter String axions (almost massless pseudoscalars in string theory) One of them may solve CP problem Axion-like particles (ALPs) Generic two-photon vertex, could be dark matter (2 parameters m a and g aγ ) Hidden photons Low-mass gauge bosons from U (1) (kinetic mixing parameter χ and mass m γ ) Chameleons Scalars in certain models of scalar-tensor gravity Motivated by dark energy Environment-dependent properties

4 Plenitude of Axions Axiverse [Joerg Jaekel]

5 CP Violation in Particle Physics Discrete symmetries in particle physics C Charge conjugation, transforms particles to antiparticles violated by weak interactions P Parity, changes left-handedness to right-handedness violated by weak interactions T Time reversal, changes direction of motion (forward to backward) CPT exactly conserved in quantum field theory CP conserved by all gauge interactions violated by three-flavor quark mixing matrix M. Kobayashi T. Maskawa Physics Nobel Prize 2008 All measured CP-violating effects derive from a single phase in the quark mass matrix (Kobayashi-Maskawa phase), i.e. from complex Yukawa couplings Cosmic matter-antimatter asymmetry requires new ingredients

6 The CP Problem of Strong Interactions Real quark mass Phase from Yukawa coupling Angle variable CP-odd quantity E B L QCD = ψ q id m q e iθ q ψ q 1 4 q ψ q e iγ 5θ q /2 ψ q L QCD = ψ q id m q ψ q 1 4 GG q G μνa G a μν Θ α s 8π G μνag a μν Remove phase of mass term by chiral transformation of quark fields Θ can be traded between quark phases and GG term No physical impact if at least one m q = 0 Θ arg det M q π Θ +π Induces a large neutron electric dipole moment (a T-violating quantity) α s 8π GG Experimental limits: Θ < Why so small?

7 Strong CP Problem QCD vacuum energy V(Θ) 4 Λ QCD Equivalent Equivalent 2π π +π +2π Θ CP conserving vacuum has Θ = 0 (Vafa and Witten 1984) QCD could have any π Θ +π, is constant of nature Energy can not be minimized: Θ not dynamical Peccei-Quinn solution: Make Θ dynamical, let system relax to lowest energy

8 37 Years of Axions

9 The Cleansing Axion Frank Wilczek I named them after a laundry detergent, since they clean up a problem with an axial current. (Nobel lecture 2004)

10 Phenomenological Axion Properties Gluon coupling (generic), defines normalization of axion scale f a L ag = α s a GG 8π f a Mass (generic) depends on up/down quark masses m a = m um d m π 6 μev m u + m d f π f a f a GeV Axion-photon coupling (model dependent) L aγ = g aγ 4 FFa = g aγ E B a = α 2π γ a γ E N 1.92 Generic from a-π-η mixing a f a E B Model-dependent, E/N = 0 (KSVZ), 8/3 (DFSZ), many others Axion-nucleon coupling (model-dependent numerical factors C N ) L an = C N Ψ N γ μ μ a Axial-vector current γ 5 Ψ N a 2f a Spin-dependent int n Axion-electron coupling in non-hadronic models is analogous with C e f f

11 Axion Bounds and Searches Future EUCLID [GeV] f a m a kev ev mev mev nev Experiments Tele scope CAST Hadronic axions ADMX Search (Seattle & Yale) CASPEr Too much hot dark matter Helium-burning stars (a-g-coupling, hadronic axions) ARIADNE IAXO String DW Too much CDM cold dark matter (misalignment) (re-alignment with Q i = 1) Anthropic Range SN 1987A Too many events Too much energy loss Globular clusters (He ignition), WD cooling (a-e coupling)

12 Let there be light

13 Experimental Tests of Invisible Axions Primakoff effect: Axion-photon transition in external static E or B field (Originally discussed for π 0 by Henri Primakoff 1951) Pierre Sikivie: Macroscopic B-field can provide a large coherent transition rate over a big volume (low-mass axions) Axion helioscope: Look at the Sun through a dipole magnet Axion haloscope: Look for dark-matter axions with a microwave resonant cavity Two-photon vertex generic for π 0, η, axion-like particles (ALPs), gravitons

14 Search for Solar Axions g Primakoff production a Axion flux a Axion Helioscope (Sikivie 1983) Magnet N S g Sun Axion-Photon-Oscillation Tokyo Axion Helioscope ( Sumico ) (Results since 1998, up again 2008) CERN Axion Solar Telescope (CAST) (Data since 2003) Alternative technique: Bragg conversion in crystal Experimental limits on solar axion flux from dark-matter experiments (SOLAX, COSME, DAMA, CDMS...)

15 Pointing a Magnet to the Sun By CAST student Sebastian Baum

16 Parameter Space for Axion-Like Particles (ALPs) Two parameters: - ALP mass m a - ALP-γ coupling g aγ Weinberg Wilczek standard axion Model dependence (KSVZ, DFSZ, ) broadens the axion line Γ a γγ = g aγ 2 3 m a 64π

17 Parameter Space for Axion-Like Particles (ALPs) CAST exclusion range

18 Parameter Space for Axion-Like Particles (ALPs) CAST exclusion range End of solar spectrum Maximal mixing ( coherent, small m a ) Large m a, a-γ-oscillations suppressed a-γ-oscillations enhanced with He filling (m γ m a )

19 Parameter Space for Axion-Like Particles (ALPs) - Improvement by a factor of 30 - Leaping into uncharted territory

20 Parameter Space for Axion-Like Particles (ALPs) - Improvement by a factor of 30 - Leaping into uncharted territory Pushing generic ALP frontier

21 Any Light Particle Search II (ALPS-II) at DESY ALPS-I (finished) ALPS-IIa (2014) ALPS-IIb (2015) ALPS-IIc (2017) ALPS-II Technical Design Report, arxiv:

22 Shining TeV Gamma Rays through the Universe Figure from a talk by Manuel Meyer (Univ. Hamburg)

23 Shining TeV Gamma Rays through the Universe Figure from a talk by Manuel Meyer (Univ. Hamburg)

24 Parameter Space for Axion-Like Particles (ALPs) ALPS-II at DESY

25 Galactic Globular Clusters

26 New ALP Limit from Globular Clusters Helium abundance and energy loss rate from modern number counts HB/RGB in 39 globular clusters Planck Ayala, Dominguez, Giannotti, Mirizzi & Straniero, arxiv:

27 Axion and ALP Dark Matter

28 Creation of Cosmological Axions by Re-alignment T ~ f a (very early universe) U PQ (1) spontaneously broken Higgs field settles in Mexican hat Axion field sits fixed at a i = Θ i f a V(a) a T ~ 1 GeV (H ~ 10 9 ev) Axion mass turns on quickly by thermal instanton gas Field starts oscillating when m a 3H Classical field oscillations (axions at rest) V(a) Θ = 0 a Axions are born as nonrelativistic, classical field oscillations Very small mass, yet cold dark matter

29 Axion Cosmology in PLB 120 (1983)

30 WISPy Cold Dark Matter General ALPs produced by re-alignment as cold dark matter Arias, Cadamuro, Goodsell, Jaeckel, Redondo, Ringwald, arxiv:

31 Axion Dark Matter Driving Oscillators π 4 Λ QCD Θ = a/f a +π Oscillating axion field (DM) Oscillating Q term Drives oscillating neutron EDM Drives oscillating E-field in microwave cavity w/ B-field Assume axions are the galactic dark matter: ρ a ~ 300 MeV/cm 3 ρ a = m a 2 Φ a 2 = m a 2 Independently of f a expect Θ t Θf 2 a Θ 2 m π f 2 π Θ 2 4 Λ QCD = a t /f a cos m a t Expect time-varying neutron EDM, MHz frequency for f a ~ 1016 GeV d n e m q Θ e cm cos m 2m n m a t N 8 orders of magnitude below limit on static EDM, but oscillates! CASPEr Project

32 Cold Axion Populations Random Θ i values Θ i = 1.57 Cosmic axion string Scenario 1 Cosmic inflation first PQ symmetry breaking at T f a Every causal patch has different random Θ i Topological defects at interfaces Axion dark matter from - average re-alignment - cosmic-string (CS) & domain-wall (DW) decay Scenario 2 Cosmic inflation after PQ symmetry breaking All axions from re-alignment of one random Θ i in our patch of the universe Allows large f a if Θ i 1 ( anthropic case) Ω a h 2 = 0.20 Θ i 2 f a GeV = 0.11 Θ i 2 10 μev m a 1.184

33 Axion decay constant f a [GeV] Isocurvature Constraints B-modes in CMB would exclude anthropic regime of large f a Classic regime B-modes in CMB would suggest large m a for dark matter axions Hubble scale during inflation [GeV] Visinelli & Gondolo, arxiv:

34 Axion Production by Domain Wall and String Decay Recent numerical studies of collapse of string-domain wall system Ω a h 2 = 8.4 ± 3.0 f a GeV 1.19 g, Λ 400 MeV Implies a CDM axion mass of m a 300 μev Hiramatsu, Kawasaki, Saikawa & Sekiguchi, arxiv: (2012) More recently by the same group m a μev Kawasaki, Saikawa & Sekiguchi, arxiv: (PRD 2015)

35 Axion Dark Matter Density Partly excluded by cosmic HDM bounds & Euclid sensitivity [arxiv: ] Hot DM Cold DM Realignment Javier Redondo 2014

36 Axion Dark Matter from Topological Defects Editor s suggestion Diversity of scenarios for cosmic axion production depending on domain-wall index N DW and phase parameter δ of the bias term

37 Pie Chart of Dark Universe Dark Energy ~70% (Cosmological Constant) Ordinary Matter ~5% (of this only about 10% luminous) Dark Matter ~25% Neutrinos 0.1-2%

38 Historical Neutrino Dark Matter Lessons Early 1980s - If neutrinos have mass, probably they are dark matter (m ν ~10 ev) ( Neutrinos are known to exist, only SM candidate) - Detection of m νe 30 ev at ITEP, Moscow (PRL 58:2019, 1987) - Dedicated oscillation experiments (NOMAD and CHORUS ) Status % of gravitating mass is dark energy - Dark matter must be mostly cold (structure formation) - Neutrinos have sub-ev masses (oscillations, cosmo limits) - Sub-dominant dark matter component History does not always repeat itself, but - If axions (or similar) exist, MUST be ALL of dark matter?

39 Dennis the Menace

40 Landscape of Axion Searches

41 CP-Violating Forces g s N g s N g s N g p e g p e g p e bulk bulk bulk spin spin spin a a a Tests of Newton s law & equivalence principle: Scalar axion coupling g s N 2 Torsion balance using polarized electron spins Axion couplings g s N g p e T-violating force Spin-spin forces hard to measure Axion couplings g s e 2

42 NMR Experiment ARIADNE: Axion Resonant InterAction DetectioN Experiment A.Geraci, A.Arvanitaki, A.Kapitulnik, Chen-Yu Liu, J.Long, Y.Semertzidis, M.Snow (to be supported by NSF and/or DoE?)

43 New Ideas for Axion Detection IAXO [Arvanitaki 2015]

44 Axion and Axion-Like Particle Searches ARIADNE WISP DMX (DESY) Center for Axion & Precision Physics (KAIST, Korea) Axion Dark Matter Experiment (UW, Seattle) ADMX-HF (Yale) MAGIC H.E.S.S. IAXO Proposal (CERN) CASPEr, HIM (Mainz) CERN

45 Dow Jones Index of Axion Physics inspire: Citation of Peccei-Quinn papers or title axion (and similar)

46 Dow Jones Index of Axion Physics inspire: Citation of Peccei-Quinn papers or title axion (and similar)