LOW ENERGY SOLAR AXIONS

Transcription

1 3rd Joint ILIAS-CERN CERN-DESY AXION-WIMPS TRAINING WORKSHOP Patras,, June 2007 LOW ENERGY SOLAR AXIONS ALESSANDRO MIRIZZI Max Planck Institut für Physik (Munich, Germany)

2 OUTILINE Primakoff axion production in the Sun CAST limit on ~ kev axion flux PVLAS inspired models and solar axion flux Low energy solar axion flux Production of solar axions in B-fields Conclusions

3 AXION PRODUCTION IN SUN In the Sun, axions are produced by Primakoff photon-axion conversions in the microscopic fluctuating E-fields of the charged particles of the plasma γ a L aγ = g E Ba aγ

4 PRIMAKOFF PROCESS IN THE SUN [G.Raffelt, PRD 33, 897 (1986)] Conversion rate g aγt ks k s 4ω Γ γ a = 1+ ln π 4ω ks Screening scale 2 4πα 2 ks = nb Ye + Z jyj T j Plasma frequency ω = παn 2 4 e pl me Axion luminosity a R 3 2 2dk ω = 4π Γ 3 ω/ T γ a (2 π) e 1 0 L dr r

5 SOLAR AXION FLUX CAST Collaboration: (hep-ex/ ) Axion-photon coupling g = ga γ / GeV Solar axion flux 1 φ a = 3.75 cm s g a Solar axion luminosity L g L 2 3 = 1.85

6 SOLAR AXION RADIAL DISTRIBUTION Most of the axion flux emerge from the inner 20% of the solar disk

7 SOLAR AXION SEARCHES Searches for solar axions: Axion helioscopes Primakoff process Axion-photon oscillation Sun Laboratory Tokyo axion helioscope Results since 1998 CERN Axion Solar Telescope (CAST) Data since 2003

8 Conversion probability axion-photon 2 2 ga γb ql g B Pa γ = L ql q aγ sin for BL 2 g 1.7 9T 9.26m q = m 2 a /2E X-rays flux at CAST φ γ L B = 0.51 cm day g 9.26 m 9.0 T

9 CAST EXCLUSION RANGE (2004 DATA) ) -1 (GeV aγ g -7-8 Lazarus et al. CAST Collaboration: (hep-ex/ ) SOLAX, COSME -9 DAMA Tokyo helioscope g aγ < 8.8 x -11 GeV -1 at 95% CL for m a < 0.02 ev - HB stars CAST phase I HDM It supersedes the limit from the Globular cluster stars Axion models -2 KSVZ [E/N = 0] -1 1 m axion (ev)

10 PVLAS AXION-LIKE PARTICLE (ALP) In 2006 the PVLAS collaboration has reported the observation of a rotation of a polarization plane of a laser propagating through a transverse magnetic field. This signal could be explained by the existence of a new axion-like particle (ALP) with ma ga γ 3 ev GeV [Zavattini et al., Phys.Rev.Lett. 96, 1406 (2006)] In serious conflict with astrophysical constraints and CAST result!

11 Solar axion luminosity by Primakoff process L = g L a For g aγ = GeV -1 L 6 a ( PVLAS ) L It can not be accomodated in a self-consistent solar model

12 [E. Zavattini et al., (hep-ex)] NEW PVLAS RESULTS

13 Different new models have been proposed to evade astrophysical constraints See, e.g., E. Masso, and J. Redondo, hep-ph/ , hep-ph/ R. Mohapatra, S. Nashri, hep-ph/06068 I. Antoniadis, A. Boyarsky, O. Ruchayskiy, hep-ph/ Beyond PVLAS, could these models have some possible signature?

14 DYNAMICAL SUPPRESSION FROM MACROSCOPIC ENVIROMENTAL PARAMETERS [Jaeckel, Masso, Redondo, Ringwald, Takahashi, hep-ph/06202] A possibility is to assume that axion-photon coupling can depend on an enviromental parameter η [E. Masso, and J. Redondo, hep-ph/ ; R. Mohapatra, S. Nashri, hep-ph/06068] g aγ ga γ( η) η = ω ρ 2 2 pl, T, ks,, q,... such that the production of ALPs is suppressed in stellar enviroment.

15 g αγ ( η) (0) g αγ η crit η

16 Saclay Solar Seismic model, Turck-Chieze et al., ApJ, 555:L69-L73, 2001

17 Referring to definiteness to PVLAS, if a flux of ALPs from a stellar plasma is suppressed by a factor S, to have a consistent scenario ( ) Sg g < g g PVLAS PVLAS CAST CAST S g CAST < gpvlas 4 20

18 In [Jaeckel, Masso, Redondo, Ringwald, Takahashi, hep-ph/06202] the suppression factor S has been evaluated as function of R crit Critical enviromental parameters are quite small, and R crit is in the region close to Sun surface.

19 LOW ENERGY SOLAR AXION FLUX If g aγ switches to the a larger value in outer regions of Sun, a low energy axion flux could result La 15 2 = 2 gl φ a 30 g cm s For g aγ = GeV -1 ~90-95 % ionization La L φ a = 1.8 cm s φ γ 190cm s CAST

20 La 18 2 = 7 gl φ a 0.17g cm s For g aγ = GeV -1 ~only H ionized L a 4 9 L φ a cm s φ γ cm s 2 CAST

21 SOLAR AXIONS FROM B-FIELD CONVERSION [Calculation by G.Raffelt] In addition to the Primakoff process, axion can be produced by photon conversions in large-scale coherent B-fields. Photon-axion conversion probability P ( ) a L = Δ a γ γ Δ = a γ g a γ 2 B ω m 2 pl a Δ osc = 4Δ aγ sin ( Δ oscl / 2) ( ) 2 Δ oscl /2 2ω 1/2

22 At resonance, m a ω pl the resonant oscillation length is L res 2π 2π 6.3 = = = Δ g B g B osc aγ 12 4 cm B B = G 4 4 which is greater than the photon mean free path in the Sun (cm): photons scatter before an oscillation cycle is complete Conversion rate Γ = γ a Pa γ L 1 L is the photon mean-path in Sun

23 SOLAR AXION FLUX Even slightly off resonance the transition rate is very much smaller than the on-resonance rate. For a given axion mass only a small fraction of solar volume is close to the resonance condition 2 gaγ B 2 5 a = 96ς 5 res e ma L R R T φ g B = 4 aγ 2 a res e ω / T ma e 2 R R 3 ω res res 1 where R e = d ln n e dr 1 res

24 For a simplified (exponential) solar axion model one obtains 4/3 ab, 4 2 a 2 a 5 B4 log ap, L m m = L 451 ev 451 ev After the integration over the entire Sun, the Primakoff effect dominates. However, in the region where the resonance condition is satisfied there could be a significant magnetic conversion effect.

25 SOLAR MAGNETIC FIELD B~30 T B~ 2-3 T [S.Couvidat, S. Turck-Chieze, A. Kosovichev, APJ 599, 1434 (2003)]

26 RESONANCE CONDITION (ω pl =m a ) r ~ 0.7 R sun, B ~ 30 T, T~ 150 ev r ~ 0.96 Rsun, B ~ 2 T, T~ 30 ev r ~ Rsun, B ~ -3 T, T~ ev

27 LB gl φ a 8 g cm s φ γ g cm s 2 ev/day vs. 8 ev/day Primakoff in CAST

28 LB gl φ a 1.2 g cm s φ γ = 2 g cm s For g aγ = -8 GeV -1 : 0.3 ev/s in CAST 4-2 1

29 LB 19 2 = 1.4 gl φ a = 3.2 g cm s φ γ = 5 g cm s For g aγ = GeV -1 : 3 ev/s in CAST

30 LOW ENERGY SOLAR AXIONS Primakoff r > 0.96 R sun B coversion Primakoff r > 0.98 R sun

31 CONCLUSIONS We presented a first estimation of low-energy solar axion flux, considering both Primakoff production and B-field photon-axion conversions. An observable axion flux could be produced below 0 ev, if some running of the axion-photon constant would happen in outer regions of the Sun. Looking at low energy axions could show signatures of some of the PVLAS-inspired models

32 We wait diligently for l.e.s. axions!