1. Low scale supergravity mediation in brane world scenario and hidden sector phenomenology Phys.Rev.D74:055005,2006 （ arXiv: hep-ph/0606156 ） ACFA07 in Beijing: 2007.2.5 Hideo Itoh (KEK) in collaboration with Nobuchika Okada (KEK) and Toshifumi Yamashita (SISSA)

2. 1.Introduction Standard Model We have fine-tuning prob. SM vacuum is not stable under quantum corrections since Higgs self energy is UV sensitive: Supersymmetry A possibility to solve above prob. New physics without quadratic div. in quantum corrections Minimal Supersymmetric SM (MSSM) Minimal supersymmetric extension of the Standard Model

3. But… Sparticles have not been observed yet SUSY must be broken at low energy MSSM We introduce soft breaking terms to break SUSY by hand SUSY should be spontaneously broken

4. What is the origin of SUSY breaking? SUSY is broken by hidden sector X : super field of hidden sector F X : F-term of hidden sector SUSY breaking is caused by F-term of hidden sector Basic scenario Simplest hidden sector model

5. Next we consider SUSY breaking mediation Image of SUSY breaking mediation Hidden sector MSSM sector gravity gauge anomaly gaugino… at Λ which is a mediation scale Mediated by SUSY breaking effect is mediated at mediation scale Λ ・ gauge mediation ・ gravity mediation (mSUGRA) Ex.)

6. Sfermion mass: Gaugino mass: Sparticle mass Our work We propose a new scenario of the low scale SUGRA mediation ・ Brane world scenario in warped extra dimensions ・ Mediation scale becomes low:Λ ～ 1–10TeV ・ Interesting collider phenomena as will be shown

7. 2.New low scale SUSY breaking model Λ 0 >0 Λ π <0 Extra-dim Λ Bulk <0 We conpactified 5 th dim. as S 1 /Z 2 orbifolding Solution of Einstein eq. ・ r : radius of 5 th dim. ・ y : angle of S 1 ・ k : curvature of bulk Brane setup in warped extra dimensions (Randall-Sundrum setup)

8. UV brane IR brane Extra-dim On the IR brane In effective 4-dim. theory Cutoff on the IR brane (Λ IR ) is effectively “warped down” Warp factor

9. In this setup, SUSY breaking mediation is the same as mSUGRA on the IR brane. Our new field setup on branes V H gravity IR braneUV brane Both of the hidden and visible sectors on the same IR brane

10. Warp factor is a free parameter of our model → Λ IR is a free parameter! Sparticle masses on this set up Generate from higher dimensional operators Suppressed by effective mass scale Λ IR = ω M Pl not by 4D Planck scale! 4D mSUGRA case

11. Interaction between hidden and visible sectors If Λ IR << M Pl Contact int. between hidden and visible sectors become strong! In the following, we investigate hidden sector pheno.

12. 3.Hidden sector phenomenology If the hidden sector scalar X is light enough (M X < 1TeV), it can be produced at LHC and ILC! ILC LHC Production processes are similar to Higgs productions If Λ IR is order TeV scale Can produce hidden sector at collider experiments

13. But, the decay processes are quite different as will be discussed in the following ・ Higgs production ・ X-production At LHC ・ m X ～ m h ～ 120GeV ・ Λ IR ～ 10TeV

14. X to SM fermion pair coupling Partial decay width into light fermion pairs is very much suppressed This feature is quite different in comparison with Higgs case. X to gauge boson pair coupling Decay processes (c,c 1,c 2 and c 3 are order one parameters)

15. Br M h [GeV] Branching ratio gg γγ WW ZZ tt bb Br M X [GeV] 1000 1 10 -1 10 -2 10 -3 100200 X decaysh decays

16. 10 3 10 2 10 1 10 0 10 -1 Event number ratio 5 10 100 Event number ratio is very much enhanced up to Λ IR ～ 100TeV. So we may probe hidden sector to use this signal at LHC. M h =M X =120GeV

17. Higgs production Angular distribution is quite different as you will see next. At ILC X production Higgs production

18. Angular distribution Longitudinal mode dominates Higgs case X case Transverse mode dominates

19. 6 8 4 010.20.40.60.8-0.2-0.4-0.6-0.8 2 0 [fb] Angular distribution

20. Other interesting process No SM background! We are doing simulation studies H. Itoh, K. Fujii, N. Okada & T. Yoshioka, work in progress

21. 4.Summary We have proposed a new setup of the mSUGRA in warped extra dimensions. ・ Visible and hidden sectors on the same IR brane ・ Cutoff scale can be low Enhanced contact interactions between hidden and visible fields Cutoff scale is low The hidden sector field may be produced at LHC or ILC!

22. Production cross sections become comparable with Higgs case Br(X → γγ) is enhanced event number very much in comparison with h → γγ. This signal is large and clean at LHC!! Cutoff scale ~ TeV Decay processes are quite different We may detect hidden sector at LHC and ILC! But Production processes are similar to Higgs

23. Back up slide

24. Another interesting feature In our model c1,c2,c3 = 1 Gaugino masses relation Decay width of X to VV induce

25. Every original mass scale is warped down on the IR brane. 4. 4. Λ IR ～ 10TeV is natural Ex.) In the RS brane setup, it is natural that Λ IR ～ 10TeV. From a view point of naturalness, everything looks like going well… at LHC We may probe the hidden sector. (Suppose mild hierarchy)

26. ・ Backup slide Gravitino mass 4D effective theory → should reproduce 4D gravity correctly Gravitino becomes LSP by warping down