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Using transversely polarised beams in W pair production for TGC measurements? A very first look

Using transversely polarised beams in W pair production for TGC measurements? A very first look. Filip Franco-Sollova Wolfgang Menges Klaus Desch ECFA/DESY Workshop Polarisation Session Amsterdam, 01/04/03. Motivation First Plots Next Steps. Motivation.

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Using transversely polarised beams in W pair production for TGC measurements? A very first look

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  1. Using transversely polarised beams in W pair production for TGC measurements? A very first look Filip Franco-Sollova Wolfgang Menges Klaus Desch ECFA/DESY Workshop Polarisation Session Amsterdam, 01/04/03 • Motivation • First Plots • Next Steps F.Franco-Sollova,W.Menges,K.Desch - Transverse Beam Polarisation for WW Production

  2. Motivation • If both beams can be polarised longitudinally, also transverse polarisation can become useful (insert spin rotators before IP) • One possible application might be the study of anomalous Triple Gauge Couplings in e+e-gW+W- • Transverse polarisation leads to an azimuthal asymmetry of the cross section: • Especially interesting for CP-violating anomalous couplings (they introduce a phase shift in the phi asymmetry = new observable not present for LPOL) F.Franco-Sollova,W.Menges,K.Desch - Transverse Beam Polarisation for WW Production

  3. Transverse Polarisation Thoery worked out in Fleischer,Jegerlehner,Kolodziej PRD49(1994!!)2174. Probe longitudinal W bosons at Measure azimuthal asymmetry F.Franco-Sollova,W.Menges,K.Desch - Transverse Beam Polarisation for WW Production

  4. Transverse Polarisation Both, transverse polarisation and anomalous TGC’s (including CP violating couplings) are built into the WHIZARD generator. T. Ohl, W. Kilian - thanks! F.Franco-Sollova,W.Menges,K.Desch - Transverse Beam Polarisation for WW Production

  5. Transverse Polarisation The Observable: How big is the asymmetry? Depends strongly on cosθ cut (only s-channel exhibits cos2Φ modulation) F.Franco-Sollova,W.Menges,K.Desch - Transverse Beam Polarisation for WW Production

  6. Transverse Polarisation WWgmnqq events √s = 500 GeV, 500 fb-1 generator level P(e-) = 0.8, P(e+) = -0.6 only events with cosθ<0.4 all events F.Franco-Sollova,W.Menges,K.Desch - Transverse Beam Polarisation for WW Production

  7. Transverse Polarisation statistical significance of the assymetry (for 500 fb-1) azimuthal asymmetry as a function of the cosθ cut: F.Franco-Sollova,W.Menges,K.Desch - Transverse Beam Polarisation for WW Production

  8. Transverse Polarisation Switch on anomalous coupling lg quite dramatic… F.Franco-Sollova,W.Menges,K.Desch - Transverse Beam Polarisation for WW Production

  9. Summary&Next Steps • Tools to perform an experimental study of WW production with transversely polarized beams are now available (built into • WHIZARD) seems to work • Azimuthal asymmetry is significant in the SM • Can be much larger if anomalous TGC’s are present • Check effect of CPV couplings -> phase shift in phi-distribution? • Become quantitative (estimate sensitivity to TGC’s) • If there is increased sensitivity (compared to LPOL), study detector effects + possible systematics F.Franco-Sollova,W.Menges,K.Desch - Transverse Beam Polarisation for WW Production

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