Baryogenesis in Higher Dimension Operators. Koji Ishiwata

Transcription

1 Baryogenesis in Higher Dimension Operators Koji Ishiwata Caltech In collaboration with Clifford Cheung (Caltech) Based on arxiv: BLV2013 Heidelberg, April 9, 2013

2 1. Introduction The origin of matter in the universe has been a mystery We know ~ 5% is baryon and ~ 27% is dark matter (DM) We don t know how baryon was generated and what DM is [ESA/Planck 13]

3 To generate baryon, we need to satisfy Sakharov s conditions: - B violation - C and CP violation - Departure from equilibrium [Sakharov 67]

4 Several candidates for baryogenesis have been proposed: - Leptogenesis [Fukugita, Yanagida 86] - Affleck-Dine mechanism - Electroweak baryogenesis [Affleck, Dine 85] And there re more baryogenesis scenarios: [Kuzmin, Rubakov, Shaposhnikov 85] - Asymmetric dark matter scenario - Gravitino decay [Cline, Raby 91] - etc. [Nussinov 85; Kaplan 92]

5 Gravitino decay is problematic because [Weinberg 82] - typically it is overproduced - its late decay may destroy successful big bang nucleosynthesis (BBN) They claimed that by assuming [Cline, Raby 91] - gravitino dominates the universe at its decay period R p - violation the gravitino decay generates baryon asymmetry (Axino/saxion decay can make similar scenario) [Mollerach, Roulet 92]

6 This idea can be extended to more generic but simpler context In our work, We propose a model comprised of the SM plus gauge singlet multiplet X Then it is possible that X interacts with the SM sector via higher dimension operators which violate B,C,CP O X-SM O X-SM Xuc d c d c Λ 2 Similar operator is considered in [Davoudiasl, Morrissey, Sigurdson, Tulin ʼ10]

7 We consider baryongenesis achieved by X decay This model has interesting experimental consequences: - X of can be TeV, and the model can be tested in the experiments n- n oscillation, flavor physics or proton decay - Lighter component can be DM

8 Contents 1. Introduction 2. The model 3. Numerical results 4. Conclusion

9 2. The model We introduce SM singlet Majorana fermions X I Then they couples to gauge singlet operators which violate B,C,CP : O X-SM = κ IJij Λ 2 (X Iu c i)( X J ū c j)+ λ Iijk Λ 2 (X Iu c i)(d c jd c k)+h.c. Hereafter I consider X 1,X 2 for simplicity, and X 1 is heavier component

10 The cosmology of the model We assume the universe starts at high reheating temperature Then we have four stages to baryogenesis:

11 i) ii) iii) iv) X 1 is thermalized with SM sector via X 1 decouples from SM while it s relativistic When temperature drops below its mass, X 1 redshifts as matter, then it evolves into a large fraction of the total energy decays via to generate baryon asymmetry X 1 O X-SM O X-SM

12 Baryon asymmetry - η B = n B s = Y X 1 Here - is asymmetric parameter Y X1 is yield variable defined as Y X1 = n X1 /s

13 Y X1 depends on when X 1 decays: 1) Before dominating the universe Y X1 n eq /s(t D1 ) 2) After dominating the universe There s large entropy production, which reheats the universe Y X1 3T 1 /4m 1 T 1 T D1 : decoupling temperature : secondary reheating temperature m 1 : mass of X 1 T D1 1) T 1 2)

14 Thus Y X1 is independent of initial reheating temperature - T D1 is determined by the scattering process: u i ū j X I X J,u i d j X I dk,d j d k X I ū i σvn eq H T D1 σv c 1T 2 Λ 4 - T 1 is determined by the decay process: X 1 u i d j d k, ū i dj dk,x 2 ū i u j Γ X1 H T 1 Γ X1 = λ2 1 m π 3 Λ 4 λ 2 1 = ijk λ 1ijk 2 + ij κ 12ij 2 /4

15 Finally the asymmetric parameter is given by difference between the branching ratios of X 1 u i d j d k and ū i dj dk = (Br X1 u i d j d k Br X1 ū i dj dk ) ijk = 1 20π δ 1 λ 2 1 m 2 1 Λ 2 u i d j d k X 1 u i d j d k ū l X 2 X 1 Γ X1 u i d j d k Γ X1 ū i dj dk = l Im(λ 1ijk κ 12liλ 2ljk ) m π 4 Λ 6 δ 1 = ijkl Im(λ 1ijkκ 12li λ 2ljk )

16 On the other hand, X 2 has an interesting possibility X 2 is produced - thermally at the initial reheating X 1 - by decay Y X2 = Y th X 2 + Y dec X 2 If X 2 is lighter than proton, then it can be DM Then, requiring that Ω X2 = m 2 Y X2 (s/ρ c ) 0 Ω DM m 2 is determined

17 Cosmological constraints: X 1 - should decouple relativistically X 1 - should decay before BBN X 2 - should be kept in out of equilibrium after decay X 1

18 3. Numerical results [Cheung, KI 13] BBN limits EFT invalid Successful baryogenesis in a wide parameter region: m 1 can be TeV (when Λ 10 6 GeV ) Baryon asymmetry and DM can be explained when m kev

19 Experimental consequences Since O X-SM violates B,C,CP, it may induce detectable experimental signatures Let s see possible experimental signatures of this model in more general higher dimension operators (with different contraction of Lorentz indices), O X-SM = λ Iijk Λ 2 (X Iu c i)(d c jd c k) + λ Iijk Λ 2 (X Id c j)(u c id c k)+

20 - Neutron-antineutron oscillation [Goity, Sher 95] [Abe et al. 11] n u d d X I ū d d n Λ 10 6 GeV λ I111 1/2 1TeV m I 1/4 The region m 1 TeV(Λ 10 6 GeV) may be tested - K 0 - K 0 mixing u X I [Beringer et al. 12] [Buras, Guadagnoli 08; Buras, Guadagnoli, Isidori 10; Laiho, Lunghi,Van de Water ʼ09; Mescia, Vitro ʼ12] Λ 10 4 GeV Im(λ I111λ I122) 1/4 m 1/2 I 1TeV d K 0 K 0 s d s

21 - Proton decay p u u u d π + [Beringer et al. 12] [Aoki et al. 08] d X 2 Λ GeV λ 1/2 2 ΛQCD 250 MeV We must assume hierarchical flavor structure in λ 2ijk (e.g. minimal flavor violation)

22 Therefore, based on the experimental constraints, we can have two possible scenarios in this model; Baryogenesis with 1) unstable (no DM candidate) 2) stable X 2 X 2 (which is DM candidate) Then, for each case, the model may be testable in 1) n- n oscillation or 2) Proton decay K 0 - K 0 mixing

23 4. Conclusion We have considered a model which consists of SM and additional singlet Majorana fermions X In this framework, X are produced and decay via higher dimension operators which violate B,C,CP As a result, The observed baryon asymmetry is generated by X Light components ( O(keV) ) can be DM The model may be tested in the experiments of n- n oscillation, flavor physics or proton decay decay

24 - Neutron-antineutron oscillation Tree diagram induces oscillation operator as n- n n u d d X I ū d d n (ud)(dd)(ud)/m 5 n- n where M 5 n- n Λ 4 m I /λ 2 I111 Then τ n- n s gives [Goity, Sher 95] [Abe et al. 11] Λ GeV λ I111 1/2 1TeV m I 1/4

25 - K 0 - K 0 mixing One-loop diagram indices (dd)( s s)/m 2 K 0 - K 0 where M 2 K 0 - K 0 16π 2 Λ 4 /λ I111λ I122m 2 I d K 0 u X K 0 I s d s Then Im M 12 =1.7 ± GeV gives [Beringer et al. 12] [Buras, Guadagnoli 08; Buras, Guadagnoli, Isidori 10; Laiho, Lunghi,Van de Water ʼ09; Mescia, Vitro ʼ12] Λ GeV Im(λ I111λ I122) 1/4 m 1/2 I 1TeV

26 - Proton decay Γ(p π + X 2 ) λ2 2m p Λ 4 QCD 16πΛ 4 p u u d u d X 2 π + Then τ p π+ ν yr gives [Beringer et al. 12] [Aoki et al. 08] Λ GeV λ 1/2 2 ΛQCD 250 MeV We must assume hierarchical flavor structure in λ 2ijk (e.g. minimal flavor violation)