ALP searches at IAXO, The International Axion Observatory Javier Redondo

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1 ALP searches at IAXO, The International Axion Observatory Javier Redondo

2 Outline - axion-like particles (ALPs) in PBSM - hints of the existence of ALPs - strong CP and axions - stellar evolution - TeV-gamma-ray transparency of the universe - Dark Matters - Solar heliosopes, IAXO

3 IAXO is an Axion-like particle detector Helioscope idea, Sikivie PRL 1986 Axion-like particle (small mass and small coupling to two photons) L 2 g 4 F µ e F µ Shielding N X-ray lens p +,e, 2+ S X-ray detector ALPs are produced inside the Sun via the two photon coupling (and others) and scape easily - B s of order 3 T, - L s of order 20 m - order Zero backgrounds

4 Theory provides us with ALP candidates pseudo Nambu Goldstone bosons Global continuous symmetry spontaneously broken at high energy scale M implies a low mass particle (Nambu-Goldstone boson) with weak couplings g 2 M Existing examples: 0,, 0,... Hypothetical fancies: axion, majoron, R-axion, familons, and a loooong etc. stringy axions & string Axiverse Arvanitaki, Dimopoulos Phys.Rev. D81 (2010) Scalars and pseudoscalars that govern the sizes and deformations of extra dimensions, gauge couplings,etc... (typically there are O(100) of these) g 2 M string Moduli, Radion, Dilatons

5 Phenomenology offers some hints - I Strong CP problem We expect P and T to be violated in a generic QCD-like theory, the size of the violation is set by : the theta angle, L = n s 8 tr G µ a e G aµ o However, NO neutron Electric Dipole Moment, nor any other sign of P, T or CP violation in the strong interactions has ever been measured!! < Peccei-Quinn-Weinberg-Wilczek showed that a pseudo Nambu-Goldstone boson, solves the problem L = n s 8 tr G µ a e G aµ o + a f a Peccei,Quinn 1977, Weinberg 1978, Wilzcek 1978 V e - Relevant AXION couplings to SM particles, always suppressed by 1/f a q, N, e a - Mixing with pseudoscalar mesons gives the AXION a mass hai f a m a ' m f i f a ' 6 mev 109 GeV f a

6 Phenomenology offers some hints - II White dwarf cooling e Z Axion emission can accelerate the WD cooling between neutrino and surface dominated cooling periods. a g ae C em e f a, a? Period decrease of G117 B15A Corsico et al. arxiv: WD luminosity function Miller Bertolami, Isern et al. arxiv: g ae =0, 1.4, 2.8 (10 13 ) period decrease rate g ae / Number of WDs/ Vol & Luminosity -log luminosity

7 Phenomenology offers some hints - II Tip of M5 s RGB e Z Axion emission delays the Helium flash makes Red giants grow brighter a g ae C em e f a Viaux, Redondo, Raffelt et al arxiv: , a? M5 color-magnitude diagram

8 Phenomenology offers some hints - II neutron star cooling Leinson, arxiv: CAS A neutron star observations for 10 years (Chandra) - Evidence for n cooper pairing + neutrino emission?... factor of 2 missing n + n! 3 P 2 + a (coupling to neutrons)

9 Phenomenology offers some hints - III Transparency of the universe to gamma rays Gamma rays pair-produce electron/positron pairs from the extragalactic background light... some cannot arrive to earth However, they do...(roncadelli et al PRD 84, Sanchez-Conde et al JCAP 1111, Horns and Meyer JCAP 1202) Excess persists at 2 4

10 Phenomenology offers some hints - III Transparency of the universe to gamma rays and ALPs Photons can convert into ALPs in galactic or extra galactic magnetic fields and reconvert back close to us Points to ALP couplings (Meyer 2012) g GeV 1 Requires ~nev ALP masses

11 Phenomenology offers some hints - IV Dark stuff Cosmology demands 2(3) new substances: (the 3 of them can be ALPs) - Dark Energy (very weakly coupled or chameleons) - Dark Radiation (only hints so far) - Dark Matter (cold or mildly warm; non-thermal) N e =3.90 ± 0.44(1 ) PDG 2012; Nollet and Holler arxiv: cdm =0.22(3) DE =0.73(3)

12 Axion/ALP hot/warm Dark Matter Cadamuro, Redondo arxiv: ALPs are thermally produced in the early universe by a number of processes q they can also decay and affect cosmology! They can explain the 3.5 kev line Jaeckel, Redondo, Ringwald arxiv: If light, they should be a subdominant component of DM hdm,a DM,obs < 0.03 Hannestad et al. JCAP 1008 Or Dark radiation N e 0.04 Cadamuro arxiv: Moduli decay into ALPs can be much more efficient N e O(4) Takahashi arxiv: , Conlon, arxiv: soft X-ray excess kev line!!

13 Axion/ALP cold Dark Matter Vacuum realignment mechanism (x) = (x)e i a(x) a fa V ( )= ( 2 f a ) cos 4 f a - Early times m a t<1, vacuum homogeneizes (modes kt<1 decay) - At m a t~1, a rolls to its minimum and oscillates cdm 4 Rosc R(t) 3 energy density redshifts as CDM! String-wall decay a = 3 2 a =0 a = a = 2 - Cosmic strings form - Scaling #/horizon~1 - Oscillations and loop decay -> axions (k~1/t ) a =0 - At m a t~1 walls collapse the strings -> more axions

14 ALP Cold dark matter 3 cdm 4 Rosc / [m 2 f 2 ] 2 m 3/2 / R(t) p m g 2 Arias, Redondo et al : arxiv: Standard Inflation singles out initial condition 9 CAST Sumico EBL HB 9 CAST Sumico EBL HB Log 10 g GeV 1 12 QCD Axions ALP DM Optical x ion Log 10 g GeV 1 EBL 12 Τ QCD Axions ALP DM Optical x ion EBL Τ 15 Axion DM X Rays 15 Axion DM X Rays Log 10 m Φ ev Log 10 m Φ ev 3.5 kev line; Jaeckel, Redondo, Ringwald arxiv:

15 The International Axion Observatory

16 IAXO is an Axion-like particle detector Helioscope idea, Sikivie PRL 1986 Axion-like particle (small mass and small coupling to two photons) L 2 g 4 F µ e F µ Shielding N X-ray lens p +,e, 2+ S X-ray detector ALPs are produced inside the Sun via the two photon coupling (and others) and scape easily - B s of order 3 T, - L s of order 20 m - order Zero backgrounds

17 Solar Axion-like particle flux well understood Redondo arxiv: Photon-ALP coupling L 2 g 4 F µ e F µ Electron-ALP coupling L 2 g e 2m e [ e µ 5 e ]@ µ g = GeV g e = 10 13

18 Detection: coherent Inverse Primakoff N S In a B-field, ALPs and photons are NOT propagation eigenstates apple 1 0 L 2 g + 4 F e µ F µ = g E B g a B! g a B! m 2 a A a = 0 0. Axion-Photon conversion probability after a length L P (! )= 2g B! m 2! 2! sin 2 m 2 L 4! Small mass (Energy and mass independent) P (! )! g BL 2 Photons expected... not many! N dad!dt 0.14 m 2 year kev N dad!dt 14 m 2 year kev g GeV B L 3T 20m 4 2 g B L GeV 1 3T 20m 2 g g e GeV B 3T 2 2 L 20m

19 Predecessors SUMICO (Tokyo U.) B-field ~ 4 T L ~ 2.3 m CAST (CERN) B-field ~ 9 T L ~ 10 m

20 Sensitivity Photon coupling arxiv: Electron (production) + Photon (det.) coupling arxiv:

21 How much better than CAST can we do? (2011) Towards a next generation axion helioscope, arxiv: New TOROIDAL magnet, AREA!, optics, detectors ATLAS toroid Magnet Dimensions Background NGAH Meas. time S/B improvement X-ray optics ultra-low back. MICROMEGAS detectors

22 IAXO, International Axion Observatory (2014) IAXO Conceptual design report arxiv: (LOI submitted to CERN, but location open) - 90 signatures, 38 Institutions (CAST + new collaborations), Europe, US, Japan, Korea - Next steps: Memorandum of understanding, apply for funding! - R&D already going on (magnet,optics,detectors) magnet design (CERN/Saclay) optics (LLNL,DTU) detectors (Zaragoza U./Saclay)

23 IAXO sensitivity Igor Irastorza (talk at Patras 2014) link g [GeV 1 ] m [ev]

24 Direct Axion/ALP DM searches in IAXO DM Axions convert into MW photons in a resonant cavity (mass oriented design) 2 TE101 L 1 h w 0 y[m] 1 Many such cavities can be fit in IAXO (Redondo, Patras 2014) 2 + Dish-Antenna experiments to search for transients - prediction on miniclusters of axion CDM x[m] M mc M mc / acdm O(1) Zurek et al 07, See also Kolb & Tkachev 94 (Horns et al JCAP , Jaeckel & JR JCAP , PRD 88, 2013)

25 Direct Axion/ALP DM searches in IAXO g a = c 2 f a

26 Can IAXO clarify the hints?... yes! Strong CP problem m a & 1 10meV IAXO can find the axion up to - Through the photon or electron couplings - In this range, IAXO can measure, coupling and mass WD,RG,NS cooling m a & 1 10meV If the axion is responsible, IAXO can find it If it is an ALP, it can strongly depend (photon coupling might be very small) Transparency of the universe due to ALPs IAXO will settle this issue (recall g GeV 1,m. nev ) Dark matter m a mev - In the strong CS&DW-contribution scenario,, IAXO is the only experiment proposed up-to-date that can find these axions. - Also if they are s sub-dominant contribution of DM - Direct DM search can reach sensitivities to detect axions and cover huge ALP parameter space Dark radiation - Discovering the axion or an ALP immediately implies a DM and DR candidate

Axion Cosmology. Axion cold dark matter, axions from string theory, and all that. Andreas Ringwald (DESY)

Axion Cosmology. Axion cold dark matter, axions from string theory, and all that Andreas Ringwald (DESY) Implications of the early LHC for cosmology, DESY, Hamburg, 18-20 April 2012 Cold Dark Matter Candidates