Axion in Large Extra Dimensions

Transcription

1 Axion in Large Extra Dimensions Talk at ASK2011 Sanghyeon Chang Konkuk Univ. April 11, 2011 Sanghyeon Chang (Konkuk Univ.) Axion in Large Extra Dimensions April 11, / 27

2 Table of Contents 1 Introduction 2 Axion in ADD bulk 3 Bulk axion phenomenology 4 Summary Sanghyeon Chang (Konkuk Univ.) Axion in Large Extra Dimensions April 11, / 27

3 Introduction Large extra-dimensions model: To solve gauge hierarchy problem. Unify two different scale M pl and M weak. axion model: To solve strong CP problem Need intermediate scale M pl > f PQ > M weak Sanghyeon Chang (Konkuk Univ.) Axion in Large Extra Dimensions April 11, / 27

4 Extra dimensions The world can have a small thickness where in the size smaller than R, the number of spatial dimensions are increased. Sanghyeon Chang (Konkuk Univ.) Axion in Large Extra Dimensions April 11, / 27

5 Arkani-Hamed, Dimopoulos and Dvali(ADD) model The standard model(sm) fields are confined on 3D boundary but gravity resides in the (3+n)D bulk. Planck scale in (3+n)D can be written M 2 pl V nm n+2 pl(3+n), (1) V n is the volume of the extra dimensional space R n Sanghyeon Chang (Konkuk Univ.) Axion in Large Extra Dimensions April 11, / 27

6 To unify the scales M pl(3+n) M weak 1 TeV, the size of the extra dimensions R should be R V 1/n n 32 n 6 M 2 n 1 TeV MeV 1 32 where M TeV M pl(3+n) /TeV. n 17 M 2 n 1 TeV cm, (2) We assume that the size of all extra dimensions are same, R Sanghyeon Chang (Konkuk Univ.) Axion in Large Extra Dimensions April 11, / 27

7 n 2 is allowed by gravity experiment (R 0.1 cm) N-th Kaluza-Klein(KK) graviton has mass N/R For n 4, Kaluza-Klein graviton mass 1 MeV: not favored by cosmology. Sanghyeon Chang (Konkuk Univ.) Axion in Large Extra Dimensions April 11, / 27

8 Extra dimensions are compactified within a finite scale R. Sanghyeon Chang (Konkuk Univ.) Axion in Large Extra Dimensions April 11, / 27

9 Gravity resides in the bulk and SM fields are confined on 3D Sanghyeon Chang (Konkuk Univ.) Axion in Large Extra Dimensions April 11, / 27

10 Axion in ADD model If an axion is confined on 3D, the Peccei-Quinn (PQ) scale f a is bounded by M pl(3+n) 1 TeV. If it lives in the (3+n)D bulk, f 2 a V n f n+2, Since there is no other scale, natural value is f M pl(3+n) and f a M pl. Both cases cannot match with current axion bounds. Sanghyeon Chang (Konkuk Univ.) Axion in Large Extra Dimensions April 11, 2011 / 27

11 axion mass is where z = m u /m d. axion-photon interaction is m a = z f π m π (3) 1 + z f a where L aγγ = g aγγ 4 af µν F µν (4) g aγγ = α 2π model dependent C aγ has value 0.1 to 1 C aγ f a Sanghyeon Chang (Konkuk Univ.) Axion in Large Extra Dimensions April 11, / 27

12 Bounds on f a and m a (Raffelt 06) f a GeV ev mev ev kev m a Laboratory Telescope CAST ADMX Excess radiation Hot DM Cold DM Globular cluster stars (photons) GC stars & White dwarf cooling (electrons) SN 1987A Too many events Burst duration Sanghyeon Chang (Konkuk Univ.) Axion in Large Extra Dimensions April 11, / 27

13 Bounds on g aγγ and m a (CAST 11) ) -1 (GeV aγ g Photon regeneration crystals Solar (CAST) HB stars Microwave cav. -5 Axion models -4-3 KSVZ -2 SN1987A -1 Hot DM 1 m axion (ev) Sanghyeon Chang (Konkuk Univ.) Axion in Large Extra Dimensions April 11, / 27

14 Sub-space axion Assume a complex scalar field χ which contains PQ axion in (4+m)D, ã. where m < n L χ = dx 4+m M χ M χ + dx 4 ã(x A = 0) F F (5) χ χ = f 1 TeV f 2 a V m f m+2, Sanghyeon Chang (Konkuk Univ.) Axion in Large Extra Dimensions April 11, / 27

15 For n > m and f M pl(3+n) f a ( ) ( ) Mpl m/n 1 m/n f f 3(1+5m/n) f GeV. (6) TeV To have 9 GeV < f PQ < 15 GeV, we need 2/5 < m/n < 4/5. The lightest axion mass eigenvalue is bounded because of axion and KK mode mixing m a 1 2 R 1. (7) Dienes, Dudas and Gherghetta, 99 Sanghyeon Chang (Konkuk Univ.) Axion in Large Extra Dimensions April 11, / 27

16 For n=2, the PQ mass can exceed 1 2 R 1 Then PQ scale f a decouples with m a while m a 1 2 R 1. Since SN1987A cooling bound gives f > ( m ) 1 m+2 GeV. (8) For m = 1, f > 300 TeV n = 2 case is not favored in this model. Sanghyeon Chang (Konkuk Univ.) Axion in Large Extra Dimensions April 11, / 27

17 Bulk axion phenomenology In LHC, KK mode of graviton production cross section is KK axion production is σ 1 Mpl 2 ( sr) n ( s M σ 1 ( ( s sr) m fa 2 They have different energy dependences. f ) n+2 1 s, (9) ) m+2 1 s. () Sanghyeon Chang (Konkuk Univ.) Axion in Large Extra Dimensions April 11, / 27

18 Cosmological issues KK modes by thermal production at early universe can be a problem. f a = 12 GeV, m KK = 1MeV axion has lifetime 17 s which is about the age of universe. It can overclose the universe. KK graviton has the same problem. Sanghyeon Chang (Konkuk Univ.) Axion in Large Extra Dimensions April 11, / 27

19 KK graviton (with mass m G ) decay into axion is enhanced by fat brane factor (m G R) m. Γ(g KK 2a) O( 3 ) m3 G M 2 pl (m G R) m. (11) KK graviton can decay into axions faster than decay into 3D matters. However, long-lived axion KK modes from graviton KK mode decay and thermal production can cause cosmological problems. Sanghyeon Chang (Konkuk Univ.) Axion in Large Extra Dimensions April 11, / 27

20 If the reheating temperature(t R ) is very low, cosmological problems can be avoided. For n < 5, T R should be less than 1 MeV conflicts with BBN. (n = 4, m = 3) for f = 1 TeV and (n = 3, m = 2) for f = TeV graviton KK mode has short lifetimes and can be escape from overclose bound. KK mode axion of mass MeV life time is as long as age of universe. Late decay of KK mode axion is restricted by cosmic background raditation data. Sanghyeon Chang (Konkuk Univ.) Axion in Large Extra Dimensions April 11, / 27

21 Even for the low T R, (n = 4, m = 3) for f = 1 TeV and (n = 3, m = 2) for f = TeV are allowed only if KK mode axions decay dominantly into some massless fields. The field should not interact with SM fields but couples to axion strongly. Axion photon branch ratio should be suppressed. Sanghyeon Chang (Konkuk Univ.) Axion in Large Extra Dimensions April 11, / 27

22 f a, lifetimes of axion and graviton KK modes for f = 1 TeV, where M m KK MeV (m, n) R 1 [MeV] f a[gev] τ g [sec] τ a[sec] (1, 2) M M 3 (2, 3) M M 3 (2, 4) M M 3 (3, 4) M M 3 (2, 5) M M 3 (3, 5) M 6 7 M 3 (4, 5) M M 3 (3, 6) M M 3 (4, 6) M M 3 Sanghyeon Chang (Konkuk Univ.) Axion in Large Extra Dimensions April 11, / 27

23 f a and lifetimes of axion and graviton KK modes for f = TeV. (m, n) R 1 [MeV] f a[gev] τ g [sec] τ a[sec] (1, 2) M M 3 (2, 3) M M 3 (2, 4) M M 3 (3, 4) M M 3 (2, 5) M M 3 (3, 5) M M 3 (4, 5) M M 3 (3, 6) M M 3 (4, 6) M M 3 Sanghyeon Chang (Konkuk Univ.) Axion in Large Extra Dimensions April 11, / 27

24 T R and branch ration to photon bound M = 1TeV, m = 3, n = Overclosure BBN CMBR DPBR Br 1 - T R [MeV] Sanghyeon Chang (Konkuk Univ.) Axion in Large Extra Dimensions April 11, / 27

25 T R and branch ration to photon bound M = TeV, m = 2, n = Overclosure BBN CMBR DPBR Br 1 - T R [MeV] Sanghyeon Chang (Konkuk Univ.) Axion in Large Extra Dimensions April 11, / 27

26 T R and branch ration to photon bound for M = 1TeV 0-2 m = 2, n = 3 m = 3, n = 4 m = 3, n = 5 m = 3, n = 6 m = 4, n = Br 1 - T R [MeV] Sanghyeon Chang (Konkuk Univ.) Axion in Large Extra Dimensions April 11, / 27

27 T R and branch ration to photon bound for M = TeV 0-2 m = 2, n = 3 m = 2, n = 4 m = 3, n = 4 m = 2, n = 5 m = 3, n = Br 1 - T R [MeV] Sanghyeon Chang (Konkuk Univ.) Axion in Large Extra Dimensions April 11, / 27

28 Summary Intermediate scale for PQ axion in ADD model can be introduced if axion resides in the sub-spacetime of whole bulk. ADD bulk axion can solve not only strong CP problem but also graviton KK mode abundance problem in the early universe. It requires specific conditions to avoid cosmological problems. Sanghyeon Chang (Konkuk Univ.) Axion in Large Extra Dimensions April 11, / 27