1 / 14

Higgs pair production at photon collider

Higgs pair production at photon collider. Hiroshima University Nozomi Maeda 13. July 2009. PLC in ILC. Photon Linear Collider (PLC) is gamma-gamma collision option in ILC. Measurement of basic physical quantity of Higgs at PLC has been studied. e.g.)the two photon decay width of Higgs.

vidal
Download Presentation

Higgs pair production at photon collider

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Higgs pair production at photon collider HiroshimaUniversity Nozomi Maeda 13.July 2009

  2. PLC in ILC Photon Linear Collider (PLC) is gamma-gamma collision option in ILC. Measurement of basic physical quantity of Higgs at PLC has been studied. e.g.)the two photon decay width of Higgs. We study feasibility of mesurement of rare process at PLC.

  3. gg->HH Measurement of Higgs self-coupling constant l=lSM(1+dk) by gg->HH final state is 2particles include loop diagram 1. This process occurs at low energy(than e+e-). 2. l contribution to cross section is different. →Can PLC measure Higgs self-coupling constant l?

  4. Energy optimization dk=+1 L:Luminosityh:detection efficiency s:cross section hB:background suppression dk=-1 Higgs mass=120GeV

  5. Background (+,+), (-,-) main background is   gg->WW (sB~90pb)   cf.) Signal:s = 0.044fb 0.044fb/90pb = 4.9×10-7 10-7background suppression is necessary. gg->tT does not occur. Optimum energy is below tT threshold.

  6. Simulation Framework CAIN (Luminosity) Signal : gg->HH BG : gg->WW theoretical calc. program (helicity amplitude) Helas (helicity amplitude) BASES/SPRING (Integration, Generation) Quick Detector Simulator pythia (parton shower,hadronization) Analysis

  7. Luminosity spectrum total luminosity of photon collision = 1.26×1035cm-2s-1 effective cross section(Signal) = 0.013fb → 16event/year effective cross section(BG) = 11,600fb → 1.467×107event/year hB<10-6 is required.

  8. Signal : gg->HH  H -> bB or WW* or gg … • Background : gg->WW   W -> ud or cs or en… Analysis choose HH->4b(Branching ratio = 0.43). background:WW->4quark →reconstruct particles, and try to distinguish them.

  9. Event reconstruction choose 2jets from 4jets, and reconstruct Higgs(or W-boson) from this 2jets. → 3 combinations for 1event. → choose a combination that has the smallest c2. M1,M2 = reconstructed particle mass M = MH or MW  s2j = 2jets mass resolution

  10. mass distribution black:HH->Allred:WW->All c2 distribution s(gg->HH)×105 choose this region Selection by c2 isnot enough to suppress background. →b-tagging is necessary.

  11. b-tagging by simulation b-tag requirement : nsig = 3.5, noffv = 2 # of b-tagged jets = 4 cutting line

  12. Event selection Background : 45,000,000event -> 0event Signal : 50,000event -> 5,483event (hSignal=0.110) If PLC runs for 5 years... 16events/year×5years×0.110 ≒ 9events → 2.96s

  13. Summary • We study feasibility of measurement of Higgs self-coupling constant l at PLC. • If Higgs mass = 120GeV, optimized photon collision energy is 270GeV. • # of Signal event is expected 16events/year with PLC parameter(TESLA optimistic). • Selection by b-tagging and kinematics parameters can suppress almost gg->WW. • gg->HH can be observed with 2.96s in 5years.

  14. Next plan • consider HH->bBWW*(B.R.=0.18). • consider gg->4b • use FlavourGetter in order to study remaining events.

More Related