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Status report on γ WW Couplings at a γγ – collider at TESLA

Status report on γ WW Couplings at a γγ – collider at TESLA. K.M önig, J.Sekaric DESY-Zeuthen. Introduction. Dominating diagram for γγ  W + W -. Ambiguities : ( cos θ 1,2 , φ 1,2 ) ↔ (- cos θ 1,2 , φ 1,2 + π ). q. . y. W BACKWARD.  1. x.  2. x.  1. z.  2. z. . y.

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Status report on γ WW Couplings at a γγ – collider at TESLA

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  1. Status report on γWW Couplings at a γγ– collider at TESLA K.Mönig, J.Sekaric DESY-Zeuthen

  2. Introduction Dominating diagram for γγ W+W- Ambiguities : (cosθ1,2,φ1,2) ↔ (-cosθ1,2,φ1,2+π) q  y WBACKWARD 1 x 2 x 1 z 2 z  y WFORWARD q 

  3. Total Cross-Section - Whizard

  4. Differential Cross-Section - Whizard Deviation effects of WLL’s in presence of anomalous coupling Δκγ, ~ ‰ for LL Deviation effects of WLT’s in presence of anomalous coupling Δλγ, , ~% for LT

  5. Analysis • Signal (γγ→WW) sample (background, pile-up), Jz=0,2 (WHIZARD – W. Kilian & CIRCE2 – T. Ohl, variable energy spectra, polarized beams) - background : γγ qq (without top, separately) 4 jets (QCD g-emission) - pileup : low-energy γγ qq (1.8 ev/BX) • Response of a detector simulated withSIMDET V4 • Ws are reconstructed fromhadronic final states • Estimated errorsof measurement ofand  parameters,obtained by fit (binned Likelihood )

  6. Pileup rejection …track selection via impact parameter I (xy, z) pileup pileup clean clean good tracks bad tracks true vertex true - reconstructed abs (IXY/σXY) < 2 abs (IZ/σZ) < 2 Beam spot (simulated) ~ 300 μm (along z-axis) Mass distribution of W boson Separation efficiency … and no more pileup rejection !

  7. Selection After -> EFF= 93% Jz = 2 Accepted events NENFLO>40, NCT>20 After -> EFF= 47% Background After -> EFF= 97% clean Signal pileup

  8. After -> EFF= 84% J1,J2  WFORWARD Jz = 2 J3,J4  WBACKWARD 40º < accepted events < 140º After -> EFF= 11% After -> EFF= 88% Background clean Signal θ(J3-J4) [deg] pileup θ(J1-J2) [deg]

  9. Jz = 2 After -> EFF= 84% After -> EFF= 5% MWF MWB MTOT MTOT=MWF+MWB After -> EFF= 53% After -> EFF= 1.8% P = 80% cosθ

  10. After -> EFF= 46% Jz = 0 After -> EFF= 97% Accepted events NENFLO>40, NCT>20 40º < accepted events < 140º θ(J3-J4) [deg] After -> EFF= 88% After -> EFF= 10% θ(J1-J2) [deg]

  11. After -> EFF= 84% Jz = 0 After -> EFF= 4% MWB MWF MTOT=MWF+MWB After -> EFF= 52% After -> EFF= 1.6% P = 83% cosθ

  12. Monte Carlo Fit Each event described with 5 kinematical variables (sensitive to TGC) : • - W production angle, cosθof W-boson • - W polar decay angles, cosθ1,2 (sensitive to the different W helicity states) of higher energetic jet • azimuthal decay angles,1,2(sensitive to the interference between different W helicity states) of higher energetic jet Matrix element calculations (WHIZARD-O’Mega)  weights to reweight SM events (Δκγ=0, Δλγ=0) as functions of anomalous TGC by Weight/event: R(,) = 1 + A· + B·()2 + C· + D·()2 + E · 

  13. + 6-th dimension center-of-mass energy ND=NSM- data sample (SM), NMC- Monte Carlo sample [NSM·R(,)],L– error on luminosity measurement

  14. Error Estimations Estimated errors for and - two-parameter 6D fit for Jz=0,2 at DETECTOR level, events in whole energy region

  15. Error Estimations Estimated errors for and - two-parameter 6D fit for Jz=0,2 at DETECTOR level, events in whole energy region

  16. Conclusions • Pileup rejection is not sufficient (still large contribution) • Good signal/background separation • Δλγsensitive to the variable energy • Anyway, error estimations Δκγ, Δλγ ~ 10-4 • …and background will be included soonin error estimation

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