Set of sum rules for anomalous gauge boson couplings

Abstract

The dependence of the differential cross section for on-shell W-pair production on the anomalous trilinear gauge couplings invariant under C and P is examined. It is shown that the contributions of the anomalous magnetic moments of the W boson due to the photon and the Z can be individually projected out by means of two appropriately constructed polynomials. The remaining four anomalous couplings are shown to satisfy a set of model-independent sum rules. Specific models which predict special relations among the anomalous couplings are then studied, in particular, the composite model of Brodsky and Hiller and linear and non-linear effective Lagrangian approaches. The relations predicted by these models, when combined with the aforementioned sum rules, give rise to definite predictions, particular to each model. These predictions can be used, at least in principle, in order to exclude or constrain such models. Finally, we present an elementary discussion of the statistical properties of the proposed observables.

Probing theWWγvertex at hadron colliders

“…It is important to observe that the polynomials P i (x) andP i (x) are independent of the (sub)process energy s. This is to be contrasted to the equivalent set of polynomials obtained in the context of the process e + e − → W + W − [3], which depend explicitly on the (fixed) s. As we will explain in section 5 the s-independence of the polynomialsP i (x) is crucial for the applicability of the proposed method to the realistic case of pp and pp scattering, where the structure functions must be included. By means of the polynomialsP i (x) one may then invert Eq.…”

“…In this paper we extend to hadron collider experiments a model-independent method proposed for the extraction of bounds on the anomalous couplings at LEP2 [3]. This method is based on constructing appropriate projections of the differential cross section [4], which lead to a set of novel observables; the latter are related to the anomalous couplings by means of simple algebraic equations.…”

Method for determining anomalous gauge boson couplings frome+e−experiments

“…Recently a model-independent method has been proposed for extracting values or bounds for the anomalous gauge boson couplings from e + e − → W + W − experiments [12]. The basic idea is to study projections of the differential cross-section which arise when the latter is convoluted with a set of appropriately constructed polynomials in cos θ, where θ is the center-of-mass scattering angle.…”

“…In addition, the trilinear gauge self-couplings have also been probed through direct W γ and W Z production at the Tevatron [9,10]. The study of such couplings is expected to continue at the CERN Large Hadron Collider (LHC), as well as the Next Linear Collider (NLC) [11].Recently a model-independent method has been proposed for extracting values or bounds for the anomalous gauge boson couplings from e + e − → W + W − experiments [12]. The basic idea is to study projections of the differential cross-section which arise when the latter is convoluted with a set of appropriately constructed polynomials in cos θ, where θ is the center-of-mass scattering angle.…”

“…This method has also been generalized to the case of hadron colliders [13], and its compatibility with the inclusion of structure function effects has been established. In what follows we will refer to this method as the "Projective Method" (PM).The PM as presented in [12] only includes terms linear in the unknown anomalous couplings (form-factors) which are individually invariant under the discrete C, P , and T symmetries. However, the inclusion of the quadratic terms as well as the C, P , and T non-invariant couplings is necessary for a complete experimental analysis.…”