The role of W-pair production at future linear colliders

1. The role of W-pair production at future linear colliders The W-pair production cross-section is an order more then one for fermion pair creation or any other reactions.This reaction is not only a big background but has to be used as main information channel replacing fermion pairs. The reaction is sensitive to new physics, connected with neutral gauge boson Z', and any modifications of gauge group structure. The analysis of decay product of W may even give us possibilities to make some kind of polarization measurement without polarized initial leptons. V. V. Gilewsky [Valentin.Gilewsky@gmail.com]

2. V.Gilewsky - Role WW on FLC

3. V.Gilewsky - Role WW on FLC LHC vs CLIC or -- JLC

4. V.Gilewsky - Role WW on FLC Standard fermion pair production

5. V.Gilewsky - Role WW on FLC Up to 160 GeV =>main discovery was made in ff-channel [PDG]

6. V.Gilewsky - Role WW on FLC H production in lowest order – e+ e- ­--> H +Z

7. V.Gilewsky - Role WW on FLC e+e-­--> H + 2*X

8. V.Gilewsky - Role WW on FLC e+e- --> W+W -

9. V.Gilewsky - Role WW on FLC Let’s compare different channels

10. V.Gilewsky - Role WW on FLC 1) Modified 3-bosons interaction

11. V.Gilewsky - Role WW on FLC Modified 3-bosons interaction

12. V.Gilewsky - Role WW on FLC Differential cross-section

13. V.Gilewsky - Role WW on FLC Total cross-section

14. V.Gilewsky - Role WW on FLC The total cross-section sensitivity to modified 3-bos interaction (G3 and G5)

15. V.Gilewsky - Role WW on FLC The differential cross-section sensitivity to modified 3-bos interaction (G3 and G5)

16. V.Gilewsky - Role WW on FLC SM fine-tuning – gauge cancellation The σ has to fall with energy • Gauge principles demand Giγ=GiZ=Gi • G3 ~ y -3/2 • G5 ~ y -1 To keep σ =const we have to have G1+G2 +1=0; To have falling σ => G1=1, G2 =-2 (SM value) For CP-non-invariant form-factors • G4 ~ y -1 • G7 ~ y -1/2 • G6 ~ const So, only SM value survive = fine tuning

17. V.Gilewsky - Role WW on FLC How rad. corrections change the situation? • We know the increasing role of corrections • Radiation corrections to angular distrib [T.Riemann at al.]

18. V.Gilewsky - Role WW on FLC 2) Z’ boson and lepton polarization

19. V.Gilewsky - Role WW on FLC Z’ boson and polarization (diff cross-sect) The case λ+=λ- gives un-polarized cross-section with overall coefficient (1-λ2). For λ- =-1 and λ+=1 cross-section is defined by only s-channels. Partial polarization gives all in the middle.

20. V.Gilewsky - Role WW on FLC Conclusion • The cross-section of WW production an order more then over ones • Form-factors by unitary consideration have to be set on SM values • Control over polarization allows to decries (cancel) the part of diagrams • The Z’ produces the similar to ff-channel peak • Even the case of un-polarized initial beams gives us possibility to analyze the polarization of final W by their decay product (vary complicated).

21. V.Gilewsky - Role WW on FLC BackUP

22. V.Gilewsky - Role WW on FLC 4-bosons interactions in SM

23. V.Gilewsky - Role WW on FLC Modification of 4-bos interactions • V. Gilevsky, Universality of additional neutral currents, Physics Letters B, 1990, vol. 249, No. 2, p. 243 - 248. • V.V.Gilewsky, I.S.Satsunkevich, General parameterization of the γγ W+W- interactions and its impact on physics at future colliders, ATL-PHYS-98-121 ; 9 March 1998, (10 p). • V.V. Gilewsky, I. S. Satsunkevich, On multiboson interactions in 1/Λ2 order, Physics Letters B, 358 (1995) p. 95 - 100. • V.V. Gilewsky, A.A. Pankov, I.S. Satsunkevich, Z' boson in e+e-→ W+W- , in book ``Physics of Elementary Interactions'', World Scientific 1991, p. 262 - 267.