The role of w pair production at future linear colliders
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The role of W-pair production at future linear colliders.

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The role of W-pair production at future linear colliders

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The role of w pair production at future linear colliders

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 [[email protected]]


The role of w pair production at future linear colliders

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Lhc vs clic or jlc

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LHC vs CLIC or -- JLC


Standard fermion pair production

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Standard fermion pair production


Up to 160 gev main discovery was made in ff channel pdg

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Up to 160 GeV =>main discovery was made in ff-channel [PDG]


H production in lowest order e e h z

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H production in lowest order – e+ e- ­--> H +Z


E e h 2 x

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e+e-­--> H + 2*X


E e w w

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e+e- --> W+W -


Let s compare different channels

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Let’s compare different channels


1 modified 3 bosons interaction

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1) Modified 3-bosons interaction


Modified 3 bosons interaction

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Modified 3-bosons interaction


Differential cross section

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Differential cross-section


Total cross section

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Total cross-section


The total cross section sensitivity to modified 3 bos interaction g3 and g5

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The total cross-section sensitivity to modified 3-bos interaction (G3 and G5)


The differential cross section sensitivity to modified 3 bos interaction g3 and g5

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The differential cross-section sensitivity to modified 3-bos interaction (G3 and G5)


Sm fine tuning gauge cancellation

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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


How rad corrections change the situation

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How rad. corrections change the situation?

  • We know the increasing role of corrections

  • Radiation corrections to angular distrib [T.Riemann at al.]


2 z boson and lepton polarization

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2) Z’ boson and lepton polarization


Z boson and polarization diff cross sect

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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.


Conclusion

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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).


Backup

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BackUP


4 bosons interactions in sm

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4-bosons interactions in SM


Modification of 4 bos interactions

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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.


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