Higgs branching ratios study

Oct. 13 2012Hiroaki Ono (NDU)

Oct. 13 2012 ILC Physics WG general meeting

Current status of Higgs BR study

• Higgs branching ratios analysis publication– Ecm=250 and 350 GeV Hbb, cc, gg channel– Submitted to EPJ, now under review…

• Detailed Baseline Document (DBD) study– Detector benchmarking study for ILD• e+e-ννh @ 1 TeV branching ratio study

– Physics chapter• Update results with Higgs mass of 125 GeV

Oct. 13 2012 ILC Physics WG general meeting

vvh detector benchmarking study

Oct. 13 2012 ILC Physics WG general meeting

e+e-vvh is one of the DBD detector benchmarking processObservable: cross section times branching ratios (σ×BRs)Decay channels: hbb, cc, gg, WW*, μμ

• Jet energy resolution (Reconstructed Higgs mass)• Jet clustering and reconstruction (with γγ BG overlay)• Flavor tagging performance (b/c tagging)• Tracking performance, momentum resolution (Hμμ)

Evaluate ILD detector performance at Ecm=1 TeV

We perform the full detector simulation with latest reconstruction packages in ILD

Higgs physics at ILC 1 TeV

Oct. 13 2012 ILC Physics WG general meeting

Higgs mainly produced via e+e- νeνeh (WW-fusion)

Final state only comes from Higgs decay• Hbb, cc, gg (two jets)• HWW* (four jets via fully hadronic decay)• Hμμ (dilepton)γγhadron BG is also overlaid as same as CLIC study

Simulation condition

Oct. 13 2012 ILC Physics WG general meeting

Higgs mass: Mh=125 GeVCM energy: Ecm=1 TeV Beam polarization: P(+-0.8, -+0.2)L=500 fb-1 for both pol.

Channel BRsbb 57.8%cc 2.7%gg 8.6%WW 21.6%μμ 0.02%

Detector model: ILD_o1_v05Simulation: Mokka v01-14-01-p00Reconstruction: Marlin v01-16-00• Detector mass simulation was finished• Mass reconstruction is still on-going

Higgs signal sample

Softwares

Higgs BRs @Mh=125 GeV

Hbb, cc, gg channel

Oct. 13 2012 ILC Physics WG general meeting

Hbb, cc, gg hadronic

• Simply final state forms two jets• γγhadron background is also overlaid on signal

• Apply forced two jet clustering at firstTry different jet clustering algorithm• Durham (LOI)• kt algorithm (used in CLIC CDR for hadron collider)• R parameter(jet-radius) should be tuned

Only check signal samples at this moment…

Invariant mass distribution

Oct. 13 2012 ILC Physics WG general meeting

Without γγhadron overlay

Invariant mass (GeV) Invariant mass (GeV)

w/o BG overlay w/ BG overlay

• Cut on the angler distribution• Different jet clustering

DurhamkT jet algorithm (as same as CLIC CDR)

kT jet clustering

Oct. 13 2012 ILC Physics WG general meeting

Invariant mass (GeV)

Dijet reconstruction with γγhadron BGUse Durham w/o BG overlay

Optimize R parameter forkT algorithm

R=1.0~1.3 looks suitable

Check with forward particlebefore jet reconstruction

Jet reconstruction with PFO cut

Oct. 13 2012 ILC Physics WG general meeting

Dijet reconstruction with γγhadron BG

w/o BG w/ BG kT w/ BG kT (cosθ<0.98) W/ BG inv. M (cosθ<0.98)

Check with small statisticsSlightly improve the PFO cosθ cut

Set R=1.1 for kT algorithm

HWW* channel

Oct. 13 2012 ILC Physics WG general meeting

HWW* (one on-shell W) from Higgs decayHWW*qqqq fully hadronic decay channel is considered

h

W1

W21. Apply forced four jet clusteringEmploy kT algorithm with R=1.0

2. Jet paring for W1, W2 (W1 is on-shell with J1, J2)Select best candidate with minimizing χ2

Reconstructed masses

Oct. 13 2012 ILC Physics WG general meeting

MH Mw1 Mw

Conclusion

• We concentrate the studies for DBD– vvH @ 1TeV– Detector simulation has been finalized– Reconstruction is now still on-going

– Schedule is quite tight but need to finalize by LCWS12

Oct. 13 2012 ILC Physics WG general meeting