1. Potential for measuring the vertex at colliders E.A., Kanemura Phys. Lett. B626, 111(2005) E.A., Kanemura, Kanzaki hep-ph/0612271 Eri Asakawa (KEK) 1.Introduction 2.The vertex 3.Measuring the vertex at LHC 4.Measuring the vertex at ILC 5.Summary

2. Exploring Higgs sector What members are included? (mass? charge? parity? CP property?) What is the mass relation among the members like? What kind of couplings do Higgs bosons have? gives us a clue to understand physics beyond SM. 2 neutral Higgs bosons (H and A) a pair of charged Higgs bosons ex.) MSSM : + one doublet Littlest Higgs model : + one triplet ・・・・・・ If Higgs sector is extended by adding a doublet, for an additional doublet will be observed. 1. Introduction  Many models beyond SM predict extended Higgs sector as a low energy effective theory.

3.  The extended Higgs sector is strongly constrained from experiments (ρparameter, FCNC, ‥‥‥ ) additional doublet : at tree level additional triplet : for each Higgs representation  vertex depends on models. additional doublet : zero at tree level additional triplet : non-zero

4. We discuss predictions of the vertex in 4 types of models: 1. models with additional doublet (more constrained) ⇒ MSSM 2. models with additional doublet (less constrained) ⇒ THDM 3. models with additional triplet with ⇒ Littlest Higgs model (+ 1 complex triplet) 4. models with additional triplet with ⇒ “Triplet model” (+ 1 complex triplet + 1 real triplet) Galison (84), Georgi, Machacek(85) Chivukula, Georgi(86) Arkani-Hamed, Cohen, Katz, Nelson (02) Han, Logan, McElrath, Wang (03)

5. 2. The vertex dim. 5 dim. 3 dominant

6. THDM Kanemura(99) MSSM Logan & Su(02) models with additional doublet

7. Littlest Higgs model Triplet model the bound from the ρparameter etc. puts upper limit forthe bound from the Zbb results puts upper limit for models with additional triplet Chen, Dawson(03) (+ 1 complex triplet) (+ 1 complex triplet + 1 real triplet)

8. Prediction for upper limits of the vertex is hierarchical for models. How small F values can be observed at LHC and ILC? E.A., Kanemura (2005)

9. Charged Higgs production at LHC 3. Measuring the vertex at LHC H  t b g W Z → ｊ ｊ → l l → b l v ⇒ It may be possible to measure the vertex for MSSM and THDM. But need Htb coupling, then useless for Triplet Higgs.

10. production via W Z fusion Partonic process proton Forward region Forward region Central region Small hadronic activity except for jets from produced Higgs bosons ⇒ possible to reach THDM case??? Pure electroweak process with no color flow in the central region. For no-Htb-vertex models like Triplet Higgs model,

11. Event generation : PYTHIA, MadGraph Simulation : under the expected detector performance at LHC Tools S/B is extremely huge!! We perform the simulation study for the WZ fusion. So, effective event selection is indispensable. E.A., Kanemura, Kanzaki (2006)

12. ,, Event selection cuts which we impose for Before cuts After cuts Signal: 100% BG W+4j: 100% (130 pb) BG ttbar: 100% (490 pb) Signal: 0.2% BG W+4j: 0.003% (3.5 fb) BG ttbar: 0.0001% (0.5 fb) BG: W+4j, ttbar, ‥‥‥

13. 800 GeV Before cutsAfter cuts Signal: 100% BG W+4j: 100% (130 pb) BG ttbar: 100% (490 pb) Signal: 0.4% BG W+4j: 0.0016% (2.1 fb) BG ttbar: 0.0001% (0.5 fb) Before cuts After cuts Signal: 0.1% BG W+4j: 0.04% (56 fb) BG ttbar: 0.0008% (3.9 fb) Signal: 100% BG W+4j: 100% (130 pb) BG ttbar: 100% (490 pb) 200 GeV 500 GeV Before cuts After cuts Signal: 100% BG W+4j: 100% (130 pb) BG ttbar: 100% (490 pb) Signal: 0.2% BG W+4j: 0.003% (3.5 fb) BG ttbar: 0.0001% (0.5 fb) Then, We estimate the required |F| values to satisfy S/√B > 3 for L=600 fb-1.

14. Predictions for each model NG OK NG

15. 4. Measuring the vertex at ILC Charged Higgs production at ILC γ, include the vertex!!

16. THDM MSSM Logan & Su(02) Kanemura(99) ⇒ possible to reach even in MSSM case !!

17. 5. Summary The vertex is important because it directly depends on the global symmetry structure of the models. Prediction for the vertex is hierarchical for models. Therefore, measuring the vertex is useful to test the models. We performed the simulation study for the production process via WZ fusion. Z fusion at LHC. NG OK NG Results: If go to ILC, possible to measure. ⇒ may be too heavy at ILC ⇒ possible to measure at ILC as well.

19. 800 GeV Before cutsAfter cuts Signal: 100% BG WZjj: 100% (560 fb) BG WZ: 100% (26 pb) Signal: 0.09% BG WZjj: 0.036% (0.1 fb) BG WZ: (< 0.003 fb) Before cuts After cuts Signal: 0.02% BG WZjj: 0.008% (0.02 fb) BG WZ: (< 0.003 fb) Signal: 100% BG WZjj: 100% (560 fb) BG WZ: 100% (26 pb) 200 GeV 500 GeV Before cuts After cuts Signal: 100% BG WZjj: 100% (560 fb) BG WZ: 100% (26 pb) Signal: 0.03% BG WZjj: 0.004% (0.02 fb) BG WZ: (< 0.003 fb) BG: WZ j j, WZ, ‥‥‥

20. 200 GeV 500 GeV 800 GeV

21. 200 GeV 700 GeV Before cuts After cuts Signal: 0.3% BG WZjj: 0.004% (18 fb) Signal: 100% BG ttbar: 100% (490 pb) Before cuts After cuts Signal: 1.1% BG WZjj: 0.0008% (4 fb) Signal: 100% BG ttbar: 100% (490 pb) BG: ttbar, ‥‥‥

22. 200 GeV 700 GeV