1. Xinyu Miao Department of Physics Univ. of Arizona 03/30/07
Heavy top LHC
Xinyu Miao
Department of Physics
Univ. of Arizona
03/30/07
Work in progress with Shufang Su

2. Outline Large Hadron Collider
Hierarchy Problem and Little Hierarchy Problem
Left-Right Twin Higgs Model
Study of the Heavy Top at the LHC
Conclusion

3. Large Hadron Collider
LHC, pp, Ecm=14 TeV

4. Large Hadron Collider
LEP
~.2 TeV
Tevtron
~2 TeV
LHC
~14TeV

5. Standard Model
Where is the Higgs? 

6. The Hierarchy Problem Plank Scale ~1034GeV2 t SM Higgs mass~
EW Scale~100GeV

7. The Little Hierarchy Electroweak Precision Measurement

8. Twin Higgs model Heavy Top SM Top yL=yR SM Gauge Boson
tSM
yL=yR
tHeavy
~(100GeV)2
SM Gauge Boson
Heavy Gauge Boson
WHeavy
WSM
yL=yR
Reference: Z. Chacko, Hock-Seng Goh , Roni Harnik
JHEP 0601:108,2006

9. Heavy Particles WH
~3TeV tH
~1TeV 
~300GeV
SM Particles

10. Heavy top tH production

11. Heavy top tH decay j W tH  b t l 
3 b + 1 j + 1 lepton + missing ET

12. tH → b ϕ± Dominant background tt (one W → lν, one W→ qq), Wjjbb Cuts-
Dominant background tt (one W → lν, one W→ qq), Wjjbb
Cuts
lepton (e or μ) with pT > 30 GeV, |η|<2.5
at least three jets with pT > 50 GeV
one jet with pT > 550 GeV
cos(θbW)>0.95
f=1000 GeV f
S (fb)
S/B
S/√B
600 GeV
8.3
41.5
18.5√L
1000 GeV
6.54
32.7
14.6√L
1500 GeV
0.74
3.7
1.65√L
σ (fb) / 20 GeV
Bg: blue
F->m_TH
MtH

13. Conclusion and Outlook
LHC opens the door for the new physics beyond SM
Left-Right Twin Higgs model has rich collider phenomenology
Study the heavy top partner at LHC
Future works:
Identify Twin Higgs mechanism
Distinguish various new physics models,
e.g. little Higgs
Determine the spin of the heavy top partner