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Higgs self coupling at e + e - Linear Collider

Higgs self coupling at e + e - Linear Collider. P. Gay & Ph. Gris LPC Univ. B. Pascal -IN2P3. Introduction. Standard Model Higgs doublet ( f ) Higgs potential behaves as. the direct measurement of l hhh and indirect measurement from m h  sign of NP.

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Higgs self coupling at e + e - Linear Collider

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  1. Higgs self coupling at e+e- Linear Collider P. Gay & Ph. Gris LPC Univ. B. Pascal -IN2P3 Higgs self coupling

  2. Introduction Standard Model • Higgs doublet (f) • Higgs potential behaves as the direct measurement oflhhh and indirect measurement from mh  sign of NP Deviation between • Goal • Reconstruction of the Higgs potential • Experimental establishment of the Higgs mechanism • Benchmark for detector optimisation Higgs self coupling

  3. Standard Model Higgs self coupling

  4. Detector simulation Higgs self coupling

  5. Processes @ 800 GeV Impact of the beamstrahlung Generated w/ WHIZARD Mh=120 GeV/c2 CIRCE/ TESLA No beamstrahlung Beamstrahlung and GZ=0 complete Expected signal for 500fb-1 is ~92 events Higgs self coupling

  6. Selections Preselection signal background Selection in two branches Evis < 500 GeV Evis > 500 GeV 4 jets 6 jets Higgs self coupling

  7. “hhZ”-Selection Background signal ghhh contribution Higgs self coupling

  8. B-tagging For each event a b-tagging per jet is performed Impact parameters and jet multiplicity are combined in a multivariable estimator Not sensible to the boost (only transverse information used) Calibration has been done at 500GEV No beamstrahlung Beamstrahlung and GZ=0 Based on impact parameter information per track, combined per jet, to form a probability complete Calibration is performed with the integral of the negative part of the distribution and yields the probability that the track is coming from a light quark NB: better estimator may be achieved with 3D view Higgs self coupling

  9. “hhZ”-Selection signal Background ghhh contribution No b-like jet 4 b-like jet Higgs self coupling

  10. “hhZ”-Selection signal Background ghhh contribution Higgs self coupling

  11. “hhZ”-Selection Background+signal signal ghhh contribution Higgs self coupling

  12. “nnhh”-Selection Higgs self coupling

  13. angle measured in the cme of the pair between the higgs direction and the boost axis Background+signal signal ghhh contribution “nnhh”-Selection Higgs self coupling

  14. Numbers for 500 fb-1 Higgs self coupling

  15. ‘hhZ’ ‘nnhh’ Interpretation for 2 ab-1 Counting event only hhZ channel (6jets) nnhh channel (4jets) Combination and likelihood l=ghhh/g0 Higgs self coupling

  16. hhZ @ 500 GeV Main steps (similar to 800 GeV) 3 selections Higgs self coupling

  17. hhZ @ 500 GeV HHZ Cme=500Gev Mh=120 Gev/C2 Full polarised beams NN>0.5 for 2 ab-1 NN>0.5 likelihood Higgs self coupling

  18. Higgs self coupling: a benchmark for detector Impact of the Pflow resolution (fast simulation) Any improvements done on the the detector will save data taking 40%->30% move from 4.5 to 2 years data taking Higgs self coupling

  19. Full simulation LDC concept framework MOKKA w/ HCAL sensitive material scintillator Particle Flow Algorithm : Wolf in MARLIN RECO Events clustered in 4 jets Beamstrahlung included Higgs self coupling

  20. Event Display LDC hhZ @ 500 GeV Higgs self coupling

  21. Full simulation Signal Background Background Background M34 (masse du Higgs) 20 Nbins entre 80 et 150 pour le background PLOT Higgs self coupling

  22. Full simulation and Reconstruction Reconstruction ofp°is of importance Photons are ~20% of jet energy Motsly coming from p° Challenge for calorimeters Low energy photons Example of improvement with constraint on p° mass Higgs self coupling

  23. Full vs Fast simulation “fast simulation” “full simulation” 25 ab-1 simulated Signal “full simulation” Background Plots given for 10fb-1 Higgs self coupling

  24. Summary • @ 500 GeV, selection of the events 6 jets have been performed to hhZ final state. • @ 800 GeV, selections of the events with 4 and 6 jets have been performed to respectively cover nnhh and hhZ final states • Beamstralhung & ISR has been taken in account Realistic Fast simulation of the detector has been used • At center of mass energy of 500 GeV, hhZ process leads to • combination of hhZ and vvhh channel, at center of mass energy of 800 GeV, leads to With 2 ab-1 Full simulation is on the way Higgs self coupling

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