Search for the 2nd KK states of the mUED model at the LHC

1. Search for the 2nd KK statesof the mUED model at the LHC Kang Young Lee Konkuk U. Seoul YongPyong 2012@ Greenpia, Yong Pyong 2012. 2. 20-23

2. Based on • Sanghyeon Chang, Kang Young Lee, Jeonghyeon Song • Phys. Lett. B708, 144 (2012). • Phys. Rev. D, to appear • In preparation

3. Outlines • Introduction • mUED model • Search for the 2nd KK Higgs bosons • Search for the 2nd KK W boson • Search for the 2nd KK Gluon (preliminary) • Summary

4. Introduction : mUED at the LHC • The phenomenology of the mUED model is definitely fixed with only one model parameter, 1/R. • The 2nd KK states are comparable to (or better than?) the 1st KK states to be studied at colliders. • Only the 2nd KK CP-odd Higgs can be found at the LHC. • The 2nd KK W boson is a good candidate to be found at the early LHC. • The ttbar resonance can give a (first) direct bound on the mUED at the Tevatron via the 2nd KK gluon.

5. The universal extra dimension model (UED)

6. Virtues and drawbacks

7. The first vs. the second KK states • m(2) ~ 2 m(1) (m(n) ~ ) • The first KK states are KK parity-odd, while the second KK states are KK parity-even. • The first KK states are produced in pairs, while the second KK states are singly produced due to the KK parity. • The first KK states decay into the LKP + soft SM particles. • The second KK states can decay into SM particles via loops. • Comparable masses, less productions (loops), better detections (resonances).

8. KK expansions

9. Particle Spectra 1/R = 500 GeV, mh = 120 GeV, ΛR = 20

10. Search for the 2nd KK Higgs bosons Higgs masses where

11. Top quark masses diagonalized by where

12. In 4D, the effective lagrangian is given by CP-odd KK state is produced via gluon fusion, while CP-even state canNOT.

14. The peak is very sharp compared with the SM Higgs.

15. Productions Assuming ∫L~ 100 fb-1, about 10,000 will be produced for 1/R = 400 GeV. About hundred events of are expected.

16. Background study Irreducible background is small. (e.g. ) Reducible background is huge from QCD events. ( of order mb)

18. Search for the 2nd KK W boson W(2) masses where Direct production

19. indirect production

20. pp → W’ → eν / μν at the early LHC Selection criteria ET > 30 GeV Isolation radius MT distribution CMS collab., PLB 698, 20 (2011)

22. Soft SM particles We expect that the direct bound of the mUED will be obtained from the search for the W’ boson at the early LHC.

23. Soft SM particles It is difficult to probe the mUED through this channel at the Tevatron.

24. Search for the 2nd KK Gluon (preliminary) pp → G(2) → ttbar (resonance) Preliminary Preliminary

25. Summary • The loop-induced decays of the 2nd KK states can be substantial in the mUED model. • The CP-odd 2nd neutral KK Higgs can be observed at the LHC in the future. • The 2nd KK W bosons will provide a direct bound on the mUED model at the early LHC (2012?). • The 2nd KK gluon provide a direct bound on the mUED model at the Tevatron through the resonant ttbar channel when Λ=50/R.

26. t1 – t2 mixing angle