Probing the weak boson sector in e+e−→W+W−

Measurement of trilinear gauge boson couplings WWV, (V≡Z,γ) in e+e− collisions at 189 GeV

“…This study uses data from the final states jj ν, jjjj, X, jjX and γX (where j represents a quark jet, an identified lepton and X missing four-momentum) taken by the DELPHI detector at LEP in 1998 at a centre-of-mass energy of 189 GeV. The data are used to determine values of three coupling parameters at the W W V vertex (with V ≡ γ, Z): ∆g Z 1 , the difference between the value of the overall W W Z coupling strength and its Standard Model prediction; ∆κ γ , the difference between the value of the dipole coupling, κ γ , and its Standard Model value; and λ γ , the W W γ quadrupole coupling parameter [3].…”

$\mathrm{W^+W^-}$ production and triple gauge boson couplings at LEP energies up to 183 GeV

“…For the leptonically decaying W, the full information about the W decay angles is accessible and the matrix elements can be directly extracted according to (2). For hadronic decays of the W boson where the quark cannot be distinguished from the antiquark, only the folded angular distributions of cos θ * and φ * are directly available.…”

“…The semi-analytic program Gentle [16] is used to calculate the W + W − cross-section for the 2 The OPAL right-handed coordinate system is defined such that the origin is at the geometric centre of the detector, the z-axis is parallel to, and has positive sense, along the e − beam direction, θ is the polar angle with respect to z and φ is the azimuthal angle around z. 3 The axes of the right-handed coordinate system in the W rest-frame are defined such that z is along the parent W flight direction and y is in the direction − → e − × − → W where − → e − is the electron beam direction and − → W is the parent W flight direction.…”

“…This parameter space is very large, and it is not currently possible to measure all fourteen couplings independently. Assuming that the Lagrangian satisfies electromagnetic gauge invariance and charge conjugation as well as parity invariance, the number of parameters reduces to five, which can be taken as g z 1 , κ z , κ γ , λ z and λ γ [1,2]. In the Standard Model g z 1 =κ z =κ γ =1 and λ z =λ γ =0.…”

“…The most general Lorentz invariant Lagrangian [1][2][3][4] which describes the triple gauge boson interaction involving W bosons has fourteen independent terms, seven describing the WWγ vertex and seven describing the WWZ vertex. This parameter space is very large, and it is not currently possible to measure all fourteen couplings independently.…”