ACFA 7th Nov.9-12 2004 Taipei Taiwan Towards Higgs Precision Measurement at ILC What we have done ? & What we have to do? JAPAN LC Physics study group Higgs subgroup and KEK Minamitateya Collaboration Yoshiaki Yasui (Tokyo Management Collage)

Why Precision Measurement? What we can do after Higgs discovery @ LHC?  Higgs Precision Measurement EW SSB, mass generation Direct measurement of self coupling e+e- →hh X  luminosity upgraded LHC (SLHC)  (e+e- → hh X ) >> (e+e- → hhh X)　　　Diouadi et.al   SM New Physics!! Higgs coupling may be a probe of BSM

MSSM at ILC? But ..... Decoupling limit MH0 ≈ MH ≈ MA0 >> MZ hhh = (3gMZ/Cw)cos2sin()  3gMh02/2MW = hhhSM (MhSM=Mh0) hhhh = (3g2/Cw2)cos22   3g2Mh02/4MW2 =SMhhhh(MhSM=Mh0) Top Yukawa corrections are small Hollik et.al. Higgs self coupling = gauge coupling? We need more idea!!

Non SUSY THD at ILC? Higgs self coupling as a probe of THD Kanemura et.al LCWS’04 Paris Baryogenesis  talk by Senaha-san

Radion(graviscalar)-Higgs mixing Extra-dim at ILC? Radion(graviscalar)-Higgs mixing Ex:Warped Extra Dim model Randall Sundrum m > 2mh ⇒ hh bbbb m < mh, >> 1 ⇒ gg 0 Dominici et.al. Nucl.Phys. B671 (2003) zzh hhh =5GeV =5GeV radion mass mPlanck-warped scale

Towards Higgs Precision Measurement Machine design parameters (CM energy, Luminosity,etc.) Detailed study of SM Higgs (Simulation, RC, etc.)　　 feedback this talk New Physics at ILC (SUSY,THD,LH,Extra-Dim,etc.)

What we have done? Priority ⇒ Higgs Physics at TeV LC Higgs self coupling⇒ We started (from 2002) Top Yukawa Heavy Higgs, etc. etc..

@LCWS '02 Jeju Korea Assumption No bkg effects 100% signal efficiency dominant for ECM > 1TeV by Yasui et.al. 　LCWS’04 Paris France 　Quick Simulation (includes bkg.) study!!

Our Strategy for simulation studies Parton level Generator (tree level ⇔ GRACE-loop) LCGrace talk by Yasui, ACFA 6th India 2003 package for LC Higgs physics study: Mh ≤ 140 GeV e+e-  6f based on the GRACE System Bases ⇒ Monte Carlo integration ⇒ Cross section Spring ⇒ Events generator Hadronizer Pythia (interface from Spring to Pythia6) Simulator (Quick Simulation → Full Simulation) Analysis

Simulation Study Ecm = 1 TeV main mode  W-fusion Higgs mass = 120 GeV 　　　　　SM decay Br ISR/BSR included Signal & bkg event generator LCGrace (BASES+SPRING) Signal MC: X + hh /SM from 0.0 to 2.0 with 0.2 step Smearing simulation at parton level Jet energy resolution ~ 30%/√E (GeV) (detector R&D target value) ννhh quick analyses only for hh decaying to 4b Br(hh4b) ~ 47 % for 120 GeV SM Higgs Signal characteristics Large missing energy, missing Pt Only 4 b jets M1 jj ~ Mh M2 jj ~ Mh No isolated lepton

Signal and Background processes By LCGrace Main bkg processes 4b + missing ννbbbb (~ ννZZ, ννZγ*) ννbbh (~ ννZh) Signal (for SM)

ννhh Analysis Flow bkg further reduction 2. Separate Zhh & fusion Reconstructed ‘Higgs’ mass ννhh Analysis Flow ννbbbb = 1. Likelihood selection bkg further reduction 2. Separate Zhh & fusion different dependence (positive/negative interferences) 3. Combine with Zhh analyses for s-channel process 4. Check hh invariant mass 5. hhh measurements ννbbh =SM L = 1 ab-1 dep. of cross-section Zhh eehh /SM

ννhh ννhh selection Separate Zhh & fusion ννhh channel = =SM L = 1 ab-1 ννbbbb = counts counts ννhh ‘fusion’ =SM ννbbh ‘Zhh’ Likelihood Missing mass [GeV] (~ OPAL Higgs scheme)

HH invariant mass distributions ‘Zhh-channel’ ‘fusion-channel’ counts counts =2  SM = Zhh ννhh =SM =SM hh invariant mass [GeV] hh invariant mass [GeV] (= visible mass)

hhh Measurement sensitivity By Yamashita et.al. LCWS 2004 Mh=120 GeV Measured /SM True /SM 95%CL upper bound 95%CL lower bound 67%CL range Ilumi=1 ab-1 Pol beam= -80% @1TeV (SM Higgs Br) Use only hh4b (Br(hh4b)~47%) Eff.(4b) 80% Precise study  Radiative corrections are also important!!  Systematic study of the RC for Higgs physics at LC with GRACE

Radiative correction for e+e-ZHH GRACE Phys.Lett.B576(2003)152 Zhang et al. Phys.Lett.B578(2004)349

Radiative correction for e+e-ee HH =(O())/(tree)-1 Yasui et.al. ECFA2004 Durham UK W WG=W- 4r r=2.267% QED for Mh=120 GeV W for Mh=120GeV

Recent progress on the loop calculations Single Higgs production e+e-ZH (full number of graphs = 341) e+e-H (1350) Phys.Lett. B559 (2003) 252-262 A.Denner et.al. PLB 560(2003)196, NPB 660(2003)289 e+e-e+e- H (4470) Phys.Lett.B600(2004)65-76 top Yukawa e+e-t t H (2327) Phys.Lett. B571 (2003) 163-172 Y.You et.al.PLB 571(2003)85 A.Denner et.al. PLB 575(2003)290, NPB 68(2004)85 Multi Higgs production e+e-ZHH (5417) Phys.Lett. B576 (2003) 152-164 R.Zhang et.al.PLB(2004)349 e+e-ee　HH (19638)  New results!! of 2 to 4 Weak corrections are sizable O(5-10)%

Summary What we have done? What we have to do? A quick simulation study has been performed for Ecm=1 TeV For Mh=120 GeV: measurement sensitivity (only hhbbbb only) for =SM /SM=1.0 +0.13 -0.11 (1) 0.78 - 1.32 (95%CL) /SM=0.6 0.6 +0.10 -0.07 (1) 0.45 - 0.77 (95%CL) /SM=1.4 1.4 +0.14 -0.18 (1) 1.08 - 1.70 (95%CL) What we have to do? Non-b decay of the Higgs  increase sensitivity Mh>140GeV  W-par decay of the Higgs ννhh 8f, 10f New version of Grace system Radiative corrections (systematic study have been done) sizable  include in the event generator New Physics study