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Solving cosmological problems in Universal Extra Dimension models by introducing Dirac neutrino

Solving cosmological problems in Universal Extra Dimension models by introducing Dirac neutrino. Masato Yamanaka (Saitama University). collaborators. Shigeki Matsumoto Joe Sato Masato Senami. hep-ph/0607331. Introduction. CMB, rotating curve, and so on.

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Solving cosmological problems in Universal Extra Dimension models by introducing Dirac neutrino

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  1. Solving cosmological problems in Universal Extra Dimension models by introducing Dirac neutrino Masato Yamanaka (Saitama University) collaborators Shigeki Matsumoto Joe Sato Masato Senami hep-ph/0607331

  2. Introduction CMB, rotating curve, and so on There is a dark matter in our universe ! http://map.gsfc.nasa.gov candidate:Weakly Interacting Massive Particles(WIMPs) Universal Extra Dimension model provides a good candidate for WIMPs However this model has two shortcomings Introducing right-handed neutrino These two problems can be solved simultaneously !

  3. Today’s story What is Universal Extra Dimension model ? Radiative correction Cosmological problems Solving cosmological problemsby introducing Dirac neutrino Summary and discussion

  4. What is Universal Extra Dimension (UED) model ? 1 Universal Extra Dimension Appelquist, Cheng, Dobrescu PRD67 (2000) characteristics of UED model (time 1 + space 4) 5-dimensions compactified on an S /Z orbifold 1 2 all SM particles propagate spatial extra dimension and has the excitation mode called KK particle typical scale : 1/R = order[100 GeV] R : compactification scale 1 (S radius)

  5. What is Universal Extra Dimension (UED) model ? 2 5th dimension momentum conservation compactification ＆ orbifolding KK parity conservation at each vertex Lightest Kaluza-Klein Particle(LKP) is stable (c.f. R-parity and the LSP in SUSY) If LKP is neutral and massive, LKP can be the dark matter candidate

  6. radiative correction 1 [ Cheng, Matchev, Schmaltz PRD66 (2002) ] Radiative corrections are crucial for determining the LKP in extra dimension models Why ? 1/2 (n) 2 2 Tree level KK particle mass : m = ( n /R + m ) 2 SM 2 m : corresponding SM particle mass SM Since 1/R >> m , all KK particle masses are highly degenerated around n/R SM Mass differences among KK particles dominantly come from radiative corrections

  7. radiative correction 2 Important thing : The masses of gauge singlet particles ( U(1) gauge boson B, N , etc ) still remain ～1/R R The candidate for the neutral LKP (1) KK B boson B Dark mattercandidate (1) KK graviton G ～ 2 0 due to 1/R >> (EW scale) in the sin q ～ W mass matrix g (1) (1) B ～ ～

  8. Dark matter candidate (1) LKP : G g (1) LKP : g (1) (1) G ? Which is the LKP, or m m = d m － (1) (1) g G g (1) (1) G LKP : NLKP : For 1/R < 800 GeV ～ g (1) (1) G For 1/R > 800 GeV LKP : LKP : NLKP : ～ NLKP : Next Lightest Kaluza-Klein Particle

  9. Cosmological problems (1) For the case of G LKP Gravitational coupling is extremely weak g (1) (1) g decays into and Gin the recombination era g The emitted distorts the Cosmic Microwave Background ( CMB ) spectrum ! Hu, Silk PRL70(1993) , Feng, Rajaraman, Takayama PRL91(2003) (1) Even if G is the NLKP, these problems are replaced with the problems caused by the G late time decay (1) In this case, we can avoid the problems

  10. photon The cause of the problem Cosmological problems ( For the Big-Bang Nucleosynthesis ) decouple （1） G g （1） decay Thermal bath g nuclei early universe destroy ! Emitted photon destroys nuclei ! Present observation Big Bang Nucleosynthesis prediction Inconsistent !

  11. (1) NO ! NLKP : G 1/R > 800 GeV Constraining the reheating temperature Excluded Allowed We can avoid the cosmological problems [ Feng, Rajaraman, Takayama PRD68(2003) ] [ Kakizaki, Matsumoto, Senami PRD74(2006) ] As shown in above figure, allowed region is narrow‥ Really ? If the light (～150 GeV) Higgs is discovered, does the UED model entirely be excluded ?

  12. Solving cosmological problemsby introducing Dirac neutrino Key point Careful treatment of the neutrino mass in the UED model In the UED model, the SM neutrino is regarded as massless particle From measurements, we know that neutrino is massive In order to introduce the neutrino mass, we introduce the Dirac type neutrino (1) Mass of the KK right-handed neutrino N m 2 1 n ～ m + order (1) N R 1/R

  13. Solving cosmological problemsby introducing Dirac neutrino For excluded region ( 1/R < 800 GeV ) Before introducing Dirac neutrino m > m g (1) (1) G g g (1) Problematic is always emitted from decay After introducing Dirac neutrino m > m > m g (1) (1) (1) G N g There is no emission !!

  14. Dominant decay mode from N (1) (1) g (1) (1) Dominant photon emission decay mode from G (1) (1) g Solving cosmological problemsby introducing Dirac neutrino g We investigated some decay mode (1) g (1) h (1) N (1) g g l W l n g n g g g etc.

  15. Solving cosmological problemsby introducing Dirac neutrino g n （1） Decay rate for （1） N N (1) g (1) n 3 2 2 500GeV m d m －9 G －1 n 2×10 [sec ] = m 10 eV －2 1 GeV g （1） d m m m － = : SM neutrino mass m g （1） n N （1）

  16. Solving cosmological problemsby introducing Dirac neutrino g g （1） （1） Decay rate for G g g (1) G (1) 3 d m ´ －15 G 10 [sec ] －1 = 1 GeV [ Feng, Rajaraman, Takayama PRD68(2003) ] d m = m － m ´ g (1) G (1)

  17. Solving cosmological problemsby introducing Dirac neutrino g （1） Branching ratio of the decay g g (1) ( G ) G (1) g （1） Br( ) = g n (1) (1) ( N ) G 3 2 0.1 eV d m 1 / R －7 = 5 × 10 m 500GeV 1 GeV n g decay associated with a photon is very suppressed !! （1）

  18. g (1) Total injection photon energy from decay －18 g e (1) Y < 3 × 10 Br( ) g GeV (1) 2 2 2 W 0.1 eV h 2 m d 1 / R DM × m 500GeV 1 GeV 0.10 n e : typical energy of emitted photon Y g : number density of the KK photon normalized by that of background photons (1) The successful BBN and CMB scenarios are not disturbed unless this value exceeds 10 - 10 GeV －9 －13 [ Feng, Rajaraman, Takayama (2003) ]

  19. Summary and discussion

  20. Summary Excluded Allowed Allowed There is no excluded region in our model ! We have introduced the Dirac neutrino into the UED model, and solved cosmological problems by satisfying the necessary condition, i.e. no emission g [ Kakizaki, Matsumoto, Senami PRD74(2006) ] Our idea is applicable to extended UED model

  21. Future work 1 m 2 ～ Mass of the KK right-handed neutrino m n + order (1) N R 1/R N (0) N (1) (1) N decay is impossible ! G (1) stable, neutral, massive, weakly interaction KK right handed neutrino can be dark matter ! We are calculating the dark matter relic abundance in UED model including right-handed neutrino

  22. Appendix

  23. What is Universal Extra Dimension (UED) model ? 1 Extra dimension model Candidate for the theory beyond the standard model Hierarchy problem Large extra dimensions [ Arkani-hamed, Dimopoulos, Dvali PLB429(1998) ] Warped extra dimensions [ Randall, Sundrum PRL83(1999) ] Existence of dark matter LKP dark matter due to KK parity [ Servant, Tait NPB650(2003) ] etc.

  24. What is Universal Extra Dimension (UED) model ? 3 5th dimension momentum conservation 1 For S compactification P = n/R 5 1 R : S radius n : 0,1,2,…. KK number (= n) conservation at each vertex / P = P S 1 orbifolding － Z 5 5 2 KK-parity conservation y (0) (1) y n = 0,2,4,… y ＋1 (1) y (3) n = 1,3,5,… －1 (2) (0) At each vertex the product of the KK parity is conserved φ φ

  25. radiative correction 3 1 m = Mass of the KK graviton (1) R G Mass matrix of the U(1) and SU(2) gauge boson g g v /4 2 d 2 1/R + 2 m 2 + g v /4 2 ´ ´ (1) B g g v /4 2 + g v /4 2 1/R + 2 m 2 2 d ´ (1) W z 2 2 (3) g g ´ 39 ´ 1 d － 2 2 2 m = － ln( R ) L (1) 4 2 B 2 6 16π R 2 2 16π R z 2 g (3) g 2 5 d 2 15 m 2 2 ＋ = － (1) L ln( R ) W 2 2 4 2 2 2 16π R 16π R L : cut off scale v : vev of the Higgs field

  26. Dependence of the ‘‘Weinberg’’ angle [ Cheng, Matchev, Schmaltz (2002) ] ～ 2 sin q 0 due to 1/R >> (EW scale) in the ～ W mass matrix g (1) (1) B ～ ～

  27. Connection between collider experiment and determination of the neutrino mass type In the case of UED model There will be no evidence of the extra dimension existence for 1/R < 800 GeV In the case of UED model with right-handed neutrino KK particles can be discovered at lower energy (≦ 800 GeV) Neutrino mass type can be indirectly determined as Dirac at collider experiment !!

  28. radiative correction 2 Important things : Colored KK particles are heavier than other KK particles The masses of U(1) gauge boson and right-handed leptons still remain ～n/R The candidate for the neutral LKP (1) KK B boson B Dark mattercandidate (1) KK graviton G

  29. Excluded Allowed Cosmological problems has been solved by introducing the Dirac type mass neutrino As a result‥‥ [ Kakizaki, Matsumoto, Senami PRD74(2006) ]

  30. What is Universal Extra Dimension (UED) model ? S : 1 compactification on circle ψ(x , y) = ψ(x , y+2πR) μ μ Z : reflection symmetry under y y － 2 y : extra dimension coordinate / S 1 compactification produces Z 2 chiral theory corresponding to the SM

  31. Solving cosmological problemsby introducing Dirac neutrino + UED model small Dirac mass type neutrino We can extend the allowed region !! N : KK right handed neutrino (1) Mass of the KK right-handed neutrino m 2 1 n ～ m + order (1) N R 1/R

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