Status of LC Physics Study in Japan (II) Higgs/GRACE /Simulation study towards Higgs precision Measurement JAPAN LC Physics study group and KEK Minamitateya Yoshiaki Yasui (Tokyo Management Collage) LC Physics Study Meeting 3/6/2005 KEK

Higgs  SM  New Physics!! Higgs coupling may be a probe of BSM origin of EW SSB, mass generation ⇒ essential role in particle physics phenomena What we can do after Higgs LHC? ⇒ Higgs Precision Measurement

Direct measurement of self coupling e + e - →HH X  luminosity upgraded LHC (SLHC)   ( e + e - → hh X ) »  ( e + e - → hhh X ) Diouadi et.al MSSM at ILC  hhh = (3gM Z /C w )cos2   sin(   )  hhhh = (3g 2 /C w 2 )cos 2 2  THDM model at ILC Kanemura et.al LCWS’04 Paris Loop induced huge correction

What we have done? Priority ⇒ Higgs Physics at TeV LC 1.Higgs self coupling ⇒ We started (from 2002) 2.Top Yukawa 3.Heavy Higgs, etc. etc..

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

1) Parton level Generator (tree level ) ➢ LCGrace talk by Yasui, ACFA 6th India 2003 package for LC Higgs physics study : M h ≤ 140 GeV e + e -  6 fermion based on the GRACE System Bases ⇒ Monte Carlo integration ⇒ Cross section Spring ⇒ Events generator 2) Hadronizer Pythia (interface from Spring to Pythia6) 3) Simulator (Quick Simulation → Full Simulation) 4) Analysis Our Strategy for simulation studies

E cm = 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) Simulation Study  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 M 1 jj ~ M h M 2 jj ~ M h No isolated lepton

Signal and Background processes Signal (for SM) Main bkg processes 4b + missing ννbbbb (~ νν ZZ, νν Z γ *) ννbbh (~ νν Zh) By LCGrace Select typical diagrams (  full calculation )  Reconstruction of intermediate resonances

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  Analysis Flow

νν bbbb Likelihood νν bbh  =  = SM counts L = 1 ab -1  selection (~ OPAL Higgs scheme) L = 1 ab -1 ννbbbb ννbbh = SM =  Reconstructed ‘Higgs’ mass

Missing mass [GeV] ‘Zhh’ ‘fusion’ νν hh channel counts Separate  & fusion  dep. of cross-section e e hh Zhh / SM

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

M h =120 GeV Measured / SM True / SM 95%CL upper bound 95%CL lower bound 67%CL range I lumi =1 ab -1 Pol beam = M h =120 GeV (SM Higgs Br) Use only hh  4b (Br(hh  4b)~47%) Eff.(4b) 80% By Yamashita et.al. LCWS 2004 hhh Measurement sensitivity

A quick simulation study has been performed for E cm =1 TeV For M h =120 GeV:  measurement sensitivity (only hh  bbbb only) for = SM / SM = (1  ) (95%CL) / SM =0.6  (1  ) (95%CL) / SM =1.4  (1  ) (95%CL) Summary What we have done? What we have to do? Non-b decay of the Higgs  increase sensitivity Full 6f calculation M h >140GeV  W-par decay of the Higgs  8f, 10f New version of Grace system Radiative corrections are sizable!! systematic study have been done by Grace

GRACE ● GRACE is the Computer code – automatic calculation of tree level Feynman amplitudes ● e + e - → 6 fermions #Feynman Diagrams  O(10000) – e+e- → Zh → ZW+W- → ffffff (Mh ≧ 140GeV) – e+e- → tt-bar → bbW+W- → bbffff – e+e- → Zhh → ffbbbb (Mh ≦ 140 GeV) ● Many packages in the world – AMEGIC++, EFTT6F, LUSIFER, PHEGAS, SIXFAP, WHIZARD,.. – No useful tool in Asia!! LCGrace ≠ Full calculation, HELAS is unsupported now ● Tool development is essential for ILC physics – GRACE ver.2 → GRACE ver.3 (upgrade for multi-legs)

GRACE-loop Code for the full one-loop EW corrections Two packages in the world  FeynArt/FeynCalc e + e -  4 fermion  GRACE-loop e + e -  HH full O(a) for 2 to 4 processes GRACE for gg collider is now ready with CAIN (photon structure function) GRACE/SUSY is under construction  Non linear gauge fixing  upgrade reduce  form (by Vermaseren)

 Single Higgs production ● e + e -  ZH (full number of graphs = 341) ● e + e -  H (1350) Phys.Lett. B559 (2003) 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) 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) 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)% Recent progress on the loop calculations

e+e-   e  e HH

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

ACPP International Research Group Russia (MSU,RAS,RFBR) France (LAPTH,LAPP,LPC,LPMT,LPT) Japan (KEK)  GRACE ⇋ CompHEP Tree level multi-parton Loop calculation (GRACE-loop) MSSM (GRACE/SUSY, micrOMEHAs)

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