1. Masato Yamanaka (Tokyo university, ICRR) Collaborators Shigeki Matsumoto Joe Sato Masato Senami PHYSICAL REVIEW D 80, 056006 (2009)

2. Introduction Universal Extra Dimension (UED) model Model discrimination at LHC Motivation

3. Minimal Universal Extra Dimension (MUED) model [ Appelquist, Cheng, Dobrescu PRD67 (2000) ] 5-dimensions All SM particles propagate in spatial extra dimension (time 1 + space 4) R 4D spacetime S 1 New parameters in UED models R : compactification scale of extra dimension  cutoff scale of UED model S /Z orbifolding 2 1

4. Minimal Universal Extra Dimension (MUED) model [ Appelquist, Cheng, Dobrescu PRD67 (2000) ] 5-dimensions All SM particles propagate in spatial extra dimension (time 1 + space 4) R 4D spacetime S 1 S /Z orbifolding 2 1 Many Kaluza-Klein (KK) particles for one SM particle  SM particle  KK particle (1)(2),, ……, (n) Mass spectrum 1/R, 2/R, …..…, n/R (0)

5. Model discrimination at LHC proton g (1) q q Z l l  Missing energy q l MUED collider event

6. Model discrimination at LHC proton g q q Zl l  Missing energy q l proton g (1) q q Z l l  Missing energy q l ~ ~ ~~~ MUED collider event SUSY collider event Quite similar and difficult to discriminate !

7. Model discrimination at LHC  Supersymmetric particleSM particle SUSY MUED  SM particle  KK particle (1)(2),, ……, (n) ～

8. Model discrimination at LHC  Supersymmetric particleSM particle SUSY MUED  SM particle  KK particle (1)(2),, ……, (n) ～ (2) (0) f f V Second KK particle can couple with SM particles directly [ Datta, Kong, Matchev PRD72 (2005) ] [ Cheng, Matchev, Schmaltz PRD66 (2002) ] Mass reconstruction from dilepton clean signal Second KK photon (Z boson) decay into dilepton

9. Motivation Precise calculation of production rate of and  (2) Z Connecting our prediction to LHC data Discrimination between models and confirmation UED

10. and production KK number violating operator Production process  (2) Z

11. (0) f f V KK number violating operator All loop diagrams KK number violating vertices (gauge interaction) KK number violating vertices (Yukawa interaction)

12. KK number violating operator (2) (0) f f V

13. KK number violating operator (2) (0) f f V Significant advantages of the operator Production of, Z without kinematic suppression  (2) Clean mass reconstruction of and Z  (2)

14. Production through the KK number conserving processes Advantage ・ No loop suppression Disadvantage ・ Kinematic suppression due to pair production of second KK particles

15. Production through the KK number violating processes Advantage ・ Evading the phase space suppression Disadvantage ・ Loop factor suppression

16. Numerical result

17. Total production rate For integrated luminosity 100 fb 1 production  (2) 10 62 ( For 400 GeV – 2000 GeV )

18. Discussion : significance of each process (1) Without kinematic suppression (2) and are directly produced  (2) Z Large contribution to the total cross section, particularly for large 1/R

19. Dilepton signal For integrated luminosity 100 fb 1

20. Summary and are the key ingredients for the discrimination  (2) Z (0) f f V It can be difficult to discriminate MUED model from other models We calculated the KK number violating operator We calculated the production rate of and  (2) Z Our prediction make it possible to the model discrimination and confirmation of the MUED model

21. Appendix

22. Universal Extra Dimension (UED) model 3 families from anomaly cancellation [ Dobrescu, Poppitz PRL 68 (2001) ] Preventing rapid proton decay from non-renormalizable operators [ Appelquist, Dobrescu, Ponton, Yee PRL 87 (2001) ] [ Servant, Tait NPB 650 (2003) ] Existence of dark matter Explaining cosmic ray excess anomaly [ Appelquist, Cheng, Dobrescu PRD67 (2000) ] [ J. Chang et al. Nature 456 (2008) ]

23. [ Datta, Kong, Matchev PRD72 (2005) ] Example of mass spectrum

27. Discussion : significance of each process (1) Dominant component of Parton distribution function of proton u-quark, d-quark, gluon Reason why these processes have large cross section (2) Logarithm factor prevents the drastic decreasing of cross section

28. Summary Observation of first KK particles Speculation of the value of 1/R Observation of second KK particles through di-lepton Determination of the mass of  (2) ( Z ) Mass of ( ) = Calculated mass from speculated 1/R  (2) Z Confirmation of the second KK particles ! Confirmation of the MUED model !!  (2) ( Z )