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TRILINEAR GAUGE COUPLINGS AT PHOTON COLLIDER - e  mode

Klaus Mönig and Jadranka Sekaric. TRILINEAR GAUGE COUPLINGS AT PHOTON COLLIDER - e  mode. DESY - Zeuthen. INTRODUCTION. signal to background separation study ( e  W , hadronic decay channel) observables sensitive to trilinear gauge couplings

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TRILINEAR GAUGE COUPLINGS AT PHOTON COLLIDER - e  mode

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  1. Klaus Mönig and Jadranka Sekaric TRILINEAR GAUGE COUPLINGS AT PHOTON COLLIDER - e mode DESY - Zeuthen ECFA/DESY Linear Collider Workshop

  2. INTRODUCTION signal to background separation study (e W , hadronic decay channel) observables sensitive to trilinear gauge couplings - higher order radiative corrections : gW/162~ 10-3, (3-6) - same order deviationsof 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 SMmanifest itself : - new particles produced at a collider - precision measurements of deviations from its SM values (anomalous TGC) preliminary fitting results of parameters and  (two methods) ECFA/DESY Linear Collider Workshop

  3. EVENTSELECTION TOOLS: PYTHIA event generator SIMDETV3 detector simulation sample of 105 mixed signal and background events, generated with PYTHIA at ECM = 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

  4. Channel’s contribution: e e e e e e  q e W q   q W Z°  e W t-channel e  eZ0 s-channel  qq breamstrahlung e e e  W s-channel t-channel exchange dominates (for the signal) ECFA/DESY Linear Collider Workshop

  5. high W production cross-section (~ pb) allows us to efficiently separate signal from background( e eWeZ0eqq(QED)qq ) • Applied cuts: • acc. detector angle - 7° • number of energy flow objects* • W energy • W mass NEFO EW *electrons, photons, muons, charged and neutral hadrons and unresolved clusters that deposited energy in the calorimeters ECFA/DESY Linear Collider Workshop

  6. e eW eqq e  eZ0eqq  qq MW θ° High efficiency with low background ECFA/DESY Linear Collider Workshop

  7. 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 – cosθ1) q y e  x  1 e z W  q ECFA/DESY Linear Collider Workshop

  8. 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 (Bilenkyat al.,Nuc.Phys. B(409) (1993)22 • WHIZARD Monte Carlo tree–level generator (W.Kilian,University of Karlsruhe) ECFA/DESY Linear Collider Workshop

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

  10. 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

  11. Deviation effects of WL’s in presence of anomalous coupling ECFA/DESY Linear Collider Workshop

  12. 2D acceptance function ECFA/DESY Linear Collider Workshop

  13. Fitting results of the fit of andfor ± 1 photon polarization state – single and two parameter fit for real (e ) mode • REAL MODE - pure e-mode, known beam directions ECFA/DESY Linear Collider Workshop

  14. Fitting results of the fit of andfor ± 1 photon polarization state – single and two parameter fit for parasitic (e ) mode • PARASITIC MODE - running in -mode, could be considered as a background, unknown beam directions ECFA/DESY Linear Collider Workshop

  15. Reweighted events • WHIZARD Monte Carlo generator for 105 (ūd) pairs at ECM = 450 GeV, fixed photon beam energy, polarized beams, anomalous couplings - Nev 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

  16. 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 - single parameter fit - two parameter fit ECFA/DESY Linear Collider Workshop

  17. comparison of the single parameter fit for e ,  -, and e-e+ - colliders ECFA/DESY Linear Collider Workshop

  18. SUMMARY 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! -  ,~ 10-3 • 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 ECFA/DESY Linear Collider Workshop

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