Igor G. Irastorza Lab. Física Nuclear y Astropartículas, Departamento de Física Teórica Universidad de Zaragoza Martes Cuánticos, 2-Diciembre-2014

Transcription

1 A la caza del axión Igor G. Irastorza Lab. Física Nuclear y Astropartículas, Departamento de Física Teórica Martes Cuánticos, 2-Diciembre-2014

2 Qué es el axión? Porqué se cree que existe? Qué impacto tiene? Cómo se puede detectar? Qué se está haciendo? Next slides in english, sorry 2

3 We start by The Strong-CP problem or Why strong interactions seem to NOT violate CP? while there is no reason why this should be the case according to quantum chromodynamics (QCD) An electric dipole moment of a neutron indicates CP violating underlying physics 3

4 In QCD, nothing prevents from adding a term like that to the lagrangian: This term is CP violating. 2 contributions of very different origin From non-observation of neutron electric dipole moment: Why so small? High fine-tunning required for this to work in the SM 4

5 Peccei-Quinn solution to the strong CP problem (in 1977) New U(1) symmetry introduced in the SM: Peccei Quinn symmetry of scale f a The AXION appears as the Nambu-Goldstone boson of the spontaneous breaking of the PQ symmetry Axion lagrangian absorbed in the definition of a a/f a relaxes to zero CP conservation is preserved dinamically 5

6 The PQ scenario solves the strong CPproblem. But as a side effect, a new particle appears, the axion. (Weinberg, Wilcek) Basic properties: Neutral Gets very small mass through mixing with pions Stable (for practical purposes). Phenomenology driven by the PQ scale f a. (couplings inversely proportional to f a ) 6

7 Axion photon coupling generically present in every axion model. Other couplings possible, but less generic (model dependent) Axion-photon conversion in the presence of an electromagnetic field (Primakoff effect) This is probably the most relevant of axion properties. Most axion detection strategies are based on the axion- photon coupling 7

8 Why don t we see axions in accelerators? too weak cross-sections if f a high enough. ( invisible axions ) we need to look elsewhere 8

9 Stellar bodies lose energy by axion emission, and this may modify their: lifetime luminosity function other properties Astrophysical observations have been used extensively to constraint axion properties White dwarfs Neutron star CAS A Red Giants However, anomalous cooling has been observed in a number of stars Hints for axions? 9

10 Diagram from arxiv: Gama ray telescopes like MAGIC or HESS observe HE photons from very distant sources Hints for axion-like particles? 10

11 CDM Cosmology Dark energy ~68.3% Baryonic < 5% Visible < 1% non baryonic Dark Matter ~26.8 % 11

12 Galaxy cluster dynamics Dark energy ~68.3% CDM Cosmology CMB anisotropies Structure formation in the Universe Baryonic < 5% Visible < 1% Galaxy rotation curves non baryonic Dark Matter ~26.8 % Gravitational ti llensing Primordial Nucleosysnthesis 12

13 Dark Matter must be composed by particles non-relativistic (cold DM) neutral with mass non-baryonic beyond the Standard Model What about axions? 13

14 Axion realignment When T > T QCD <a phys > is arbitrary V When T ~ T QCD <a phys > 0 V a a As the Universe cools down below T QCD, space is filled with low energy axion field fluctuations. Their density depends on the initial value of <a phys > ( misalignment( angle ) 14

15 Axion topological defects Axion strings Domain walls But inflation may wipe out topological defects Did inflation happen before or after the creation of defects (PQ transition)? pre-inflation or post-inflation scenarios Recent BICEP2 results would point to post-inflation (but then Planck ) 15

16 Process E a a Pre-inflation Post-inflation Axion realigment Decay of axion strings Decay of domain walls Thermal Cold DM Cold DM Cold DM (m a ) Axion strings Unbounded (anthropic) m a > ~10 ev a 0 m a > ~100 ev Domain walls production Hot DM (m a ) + m a < ~1eV Conclusion: AXIONS CAN BE THE DARK MATTER Sharp predictions on m a still not possible. Model dependencies, cosmological uncertainties, Are axions the only DM component? For more details ask this guy 16

17 Axion/ALP parameter space

18 Axions solve the Strong-CP problem The Low Energy Frontier puzzle 18

19 How to detect an axion? Axion source a Photon detector 19

20 How to detect an axion? Light-shining-through-wall through experiment a Photon source WALL Photon detector 20

21 How to detect an axion? Axion helioscopes a Photon detector Axions from the Sun 21

22 How to detect an axion? Axion haloscopes a Axions from DM halo Photon detector 22

23 Light shining through wall Standard configuration Enhanced resonant configuration (future) 23

24 * ALP II under preparation (resonant, magnets, ) Martes Cuánticos, 2/12/14 Universidad de Zaragoza 24

25 Also: CERN GammeV & Fermilab,, US Toulouse Ferrara 25

26 P. Sikivie, 1983 Haloscopes Primakoff conversion inside a tunable resonant cavity Energy of photon = m a c 2 +O( 2 ) Primakoff conversion of DM axions into microwave photons inside cavity Axion DM field Non-relativistic Frequency axion mass B 0 Cavity dimensions smaller than de Broglie wavelength of axions If cavity tuned to the axion frequency, conversion is boosted by resonant factor (Q quality factor) Universidad de Zaragoza 26

27 ADMX Leading experiment: U. Washington Many years of R&D high Q cavity (1 m x 60 cm Ø) 8 T superconducting solenoid Low noise receivers based on SQUIDs Sensitivity to few ev proven New program ADMX-HF to go to higher frequencies Martes Cuánticos, 2/12/14 Universidad de Zaragoza 27

28 Axion/ALP parameter space

29 Solar Axions Solar axions produced by photonto-axion conversion of the solar plasma photons in the solar core Solar axion flux at Earth 29

30 Helioscopes Axion helioscope concept P. Sikivie, 1983 Universidad de Zaragoza 30

31 Previous helioscopes: First implementation at Brookhaven (just few hours of data) [Lazarus et at. PRL 69 (92)] TOKYO Helioscope (SUMICO): 2.3 m long 4 T magnet Presently running: CERN Axion Solar Telescope (CAST) Universidad de Zaragoza 31

32 CAST CERN Using a decommissioned LHC test magnet (L=10m, B=9 T) LHC test magnet X-ray focussing optics 2 low background Micromegas 1 low background Micromegas 32

33 DE ETECT TORS R&D at UNIZAR T-REX project OPTIC S Focal length 33

34 CAST at work Movie credit: Cenk Yildiz 34

35 Axion/ALP parameter space

36 Enhanced axion helioscope JCAP 1106:013,2011 Universidad de Zaragoza 36

37 The future: IAXO- International Axion Observatory Large toroidal 8-coil magnet L = ~20 m 8 bores: 600 mm diameter each 8 x-ray optics + 8 detection systems Rotating platform with services 10 5 better SNR than CAST 37

38 IAXO Conceptual Design IAXO Magnet: IAXO optics: ~ 600 mm Ø X 8 Inspired by NuSTAR telescope ~400 mm Ø Martes Cuánticos, 2/12/14 Universidad de Zaragoza 38

39 Work at CAST this year by UNIZAR group X-ray optics specifically built for axions Low background Micromegas 8.5 cm Calibration photons (source 14 m away) focused onto the Micromegas 39

40 Detecting DM axions with IAXO? B 0 Haloscope-type setups inside the IAXO magnet Longthin cavities in dipole magnets Large spherical mirror New approches taking advantage of the IAXO magnet geometry? PRD85 (2012) Directional effect: JCAP 1210 (2012) 022 JCAP 1304 (2013) 016 Directional effect: 40 arxiv: Studies ongoing 40

41 Axion/ALP parameter space tentative

42 Additional IAXO physics cases Particle direct physics detection at a crossroad? or relic axions/alps Axions: Promising as further pathways for IAXO beyond Growing physics case the helioscope baseline Increasing experimental activity First indications that IAXO High potential impact: could improve or complement current limits at A discovery would 3 mean various axion/alp mass 2 A portal to new ranges? physics beyond SM A new 1 window to the Universe Caution: preliminary studies still going on. Important know how to be IAXO: large scale infrastructure for the low consolidated. energy frontier? Precise implementation in IAXO under study. Tentative future prospects p Universidad de Zaragoza Beyond current LoI scope 42

43 Additional IAXO physics cases Thank direct you! detection or relic axions/alps Many people acknowledged: Local UNIZAR group (T-REX) CAST & IAXO collaborators axion community Many more 1 2 3? Universidad de Zaragoza Promising as further pathways for IAXO beyond the helioscope baseline First indications that IAXO could improve or complement current limits at various axion/alp mass ranges Caution: preliminary studies still going on. Important know how to be consolidated. Precise implementation in IAXO under study. Tentative future prospects p Beyond current LoI scope 43

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