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Potential for measuring the vertex at colliders

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

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Potential for measuring the vertex at colliders

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

  2. 1. Introduction • Many models beyond SM predict extended Higgs sector as a low energy effective theory. ex.) MSSM : + one doublet Littlest Higgs model : + one triplet ・ ・ ・ If Higgs sector is extended by adding a doublet, 2 neutral Higgs bosons (H and A) a pair of charged Higgs bosons for an additional doublet will be observed. 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.

  3. It is necessary that Higgs mechanism should give the gauge bosons their masses. Source of the gauge boson masses = Source of the Higgs-gauge couplings <Φ> <Φ> W W <Φ> <Φ> Z Z Already measured

  4. Source of the gauge boson masses = Source of the Higgs-gauge couplings h <Φ> W W <Φ> h Z Z should be measured after Higgs detection In SM,

  5. For the models with extended Higgs sector the gauge boson masses + + ‥‥ W W W W + ‥‥ + Z Z Z Z Higgs-gauge couplings observable after Higgs detection ↓ observable after Higgs detection ↓ W W W W Z Z Z Z

  6. So, the measurements of the couplings ghWW and ghZZ can be used to explore the structure of the Higgs sector. Diaz-Cruz, Lopez-Falcon (03) • The coupling gH±WZ can also be used. <Φ> H± W Z In models extended by doublet(s), H± H± + + ‥‥ = 0 W Z Z W because the rotation of the Higgs fields below is always possible: H± H± + + ‥‥ W W Z Z ω± H± H± + + ‥‥ W Z W W Z Z

  7. However, in models extended by greater representations than doublet, H± H± + + ‥‥ W Z Z W • vertex depends on models. additional doublet : zero at tree level (loop induced) additional triplet : non-zero

  8. We discuss predictions of the vertex in 4 types of models. 1. models with additional doublet (more constrained) ⇒ MSSM 2. modelswith additional doublet (less constrained) ⇒ THDM 3. models with additional triplet without custodial symm. ⇒ Littlest Higgs model (+ 1 complex triplet) 4. models with additional triplet with cutodial symm. ⇒ “Triplet model” (+ 1 complex triplet + 1 real triplet) Arkani-Hamed, Cohen, Katz, Nelson (02) Han, Logan, McElrath, Wang (03) Galison (84), Georgi, Machacek(85) Chivukula, Georgi(86) And, Potential for measuring the vertex in these models are studied.

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

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

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

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

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

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

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

  16. BG: W+4j, ttbar, ‥‥‥ Event selection cuts which we impose for VBF b-tag lepton , 500 GeV , 90 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)

  17. 200 GeV Before cuts After cuts Signal: 100% BG W+4j: 100% (130 pb) BG ttbar: 100% (490 pb) Signal: 0.1% BG W+4j: 0.04% (56 fb) BG ttbar: 0.0008% (3.9 fb) 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) 800 GeV Before cuts After 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)

  18. Then, We estimate the required |F|2 values to satisfy S/√B > 3 for L=600 fb-1. Predictions for each model ← OK Predictions for each model

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

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

  21. 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. • Weperformed the simulation study for the production process via WZ fusion at LHC. NG Results: may be possible to measure in decay (bg→H±ｔ) and ILC NG NG OK

  22. BG: WZ j j, WZ, ‥‥‥ 200 GeV Before cuts After cuts Signal: 100% BG WZjj: 100% (560 fb) BG WZ: 100% (26 pb) Signal: 0.02% BG WZjj: 0.008% (0.02 fb) BG WZ: (< 0.003 fb) 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) 800 GeV Before cuts After 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)

  23. 200 GeV 500 GeV 800 GeV

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

  25. 200 GeV 700 GeV

  26. 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

  27. Triplet Higgs Littlest Higgs THDM Higgsless

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