14-18 November, PrahaECFA/DESY Linear Collider Workshop 1 TRILINEAR GAUGE COUPLINGS AT PHOTON COLLIDER - e  mode DESY - Zeuthen Klaus Mönig and Jadranka Sekaric

ECFA/DESY Linear Collider Workshop November, Praha INTRODUCTION 1. signal to background separation study (e   W, hadronic decay channel) (e   W, hadronic decay channel) 2. observables sensitive to trilinear gauge couplings - higher order radiative corrections : g W /16  2 ~ 10 -3, (3-6) - same order deviations of the TGCs might arise if the SM is the low energy limit of a larger theory  test of EW theory, probe of some possible extensions  new physics beyond the SM manifest itself : - new particles produced at a collider - precision measurements of deviations from its SM values (anomalous TGC) 3. preliminary fitting results of parameters   and  (two methods)

ECFA/DESY Linear Collider Workshop November, Praha EVENT SELECTION TOOLS: PYTHIA event generator SIMDET V3 detector simulation  sample of 10 5 mixed signal and background events, generated with PYTHIA at E CM = 450 GeV, variable photon energy spectrum, without beam polarization and anomalous couplings  response of a detector simulated with SIMDET V3 (acceptance effects)  W reconstructed from hadronic decays (W  qq (2jets))

ECFA/DESY Linear Collider Workshop November, Praha e e  e Z°Z° W e e  W  ee q q    qq breamstrahlung q e   W t-channel Channel’s contribution: e   eZ 0 s-channel t-channel exchange dominates (for the signal) t-channel exchange dominates (for the signal) e  e e W s-channel

ECFA/DESY Linear Collider Workshop November, Praha high W production cross-section (~ pb) allows us to efficiently separate signal from background ( e   e W eZ 0  eqq  (QED)  qq ) Applied cuts: acc. detector angle - 7° acc. detector angle - 7° number of energy flow objects* number of energy flow objects* W energy W energy W mass W mass NEFO EWEW * electrons, photons, muons, charged and neutral hadrons and unresolved clusters that deposited energy in the calorimeters

ECFA/DESY Linear Collider Workshop November, Praha e   e W  e qq e   eZ 0  eqq   qq High efficiency with low background MWMW θ°θ°

ECFA/DESY Linear Collider Workshop November, Praha SENSITIVE OBSERVABLES total and differential production cross-section  sensitive to anomalous coupling  W production angle (polar angle - cosθ)  W decay angle (between the quark and the total momentum of quark pair – cosθ 1 ) e  z x y q q e W 11  

ECFA/DESY Linear Collider Workshop November, Praha TOOLS  analytic formula for total (differential) cross- section (A. Denner, A.Dittmaier, Nucl.Phys. B398 (1993)239  helicity amplitudes for different initial photon and final W states (E.Yehudai, Phys.Rev. D11(44)1991))  differential cross-section distribution over the decay angle (Bilenky at al.,Nuc.Phys. B(409) (1993)22  WHIZARD Monte Carlo tree–level generator (W.Kilian,University of Karlsruhe)

ECFA/DESY Linear Collider Workshop November, Praha 1.Analytic formula DCS in presence of anomalous coupling for J  = ± 1 state normalized to its SM value DCS for J  = ±1 state in SM

ECFA/DESY Linear Collider Workshop November, Praha W’s polarization fraction as a function of coupling parameter deviation W’s polarization fraction as a function of coupling parameter deviation - production of longitudinal Ws for J  = -1 suppressed in SM

ECFA/DESY Linear Collider Workshop November, Praha Deviation effects of W L ’s in presence of anomalous coupling

ECFA/DESY Linear Collider Workshop November, Praha 2D acceptance function

ECFA/DESY Linear Collider Workshop November, Praha Fitting results of the fit of   and  for ± 1 photon polarization state – single and two parameter fit for real (e  ) mode  Fitting results of the fit of   and  for ± 1 photon polarization state – single and two parameter fit for real (e  ) mode REAL MODE 1 par. fit E CM = 450 GeV, L = 110 fb -1 J  = +1J  = -1 LL 1%0.1%accur.1%0.1%accur.   ·   · par. fit   ·   ·  REAL MODE - pure e  -mode, known beam directions

ECFA/DESY Linear Collider Workshop November, Praha Fitting results of the fit of   and  for ± 1 photon polarization state – single and two parameter fit for parasitic (e  ) mode  Fitting results of the fit of   and  for ± 1 photon polarization state – single and two parameter fit for parasitic (e  ) mode 2 par. fit   ·   · PARASITIC MODE 1 par. fit E CM = 450 GeV, L = 110 fb -1 J  = +1J  = -1 LL 1%0.1%accur.1%0.1%accur.   ·   ·  PARASITIC MODE - running in  -mode, could be considered as a background, unknown beam directions

ECFA/DESY Linear Collider Workshop November, Praha 2.Reweighted events  WHIZARD Monte Carlo generator for 10 5 (ūd) pairs at E CM = 450 GeV, fixed photon beam energy, polarized beams, anomalous couplings - N ev normalized to previous one  matrix elements for different   and  values generated  Monte Carlo events reweighted with function R(     ) = 1 + A·   + B·   + C·(   ) 2 + D·(   ) 2 + E ·      2D cross-section distributions over cosθ and cosθ1 are fitted

ECFA/DESY Linear Collider Workshop November, Praha - single parameter fit - two parameter fit REAL MODE E CM = 450 GeV, L = 110 fb -1 J  = +1J  = -1 LL 1%0.1%accur.1%0.1%accur.   ·   ·   ·   · agreement within 10% with previous results for   and more sensitive in   determination – differs for a factor ~3 (‘better’) – still not understood - single and two parameter fit in a good agreement

ECFA/DESY Linear Collider Workshop November, Praha comparison of the single parameter fit for e ,  comparison of the single parameter fit for e ,  -, and e - e + - colliders E e  = 450 GeV L=110 fb -1 E  = 400 GeV L=110 fb -1 E ee = 500 GeV L=500 fb -1 LL 0.1%   · /   · /

ECFA/DESY Linear Collider Workshop November, Praha SUMMARY e  W production in e  collider at high energies is sensitive process to the possible scenario of EWSB  efficient signal to background separation  sensitivity to  WW only! -  ,   ~  agreement in   determination for two different fitting procedures FUTURE PLANS  low energy   qq background not included yet  signal to bck by WHIZARD (implantation of variable energy spectrum for photon beam)  fitting procedure with variable energy spectrum