Electric dipole and magnetic quadrupole moments of theWboson via aCP-violatingHWWvertex in effective Lagrangians

Abstract

The possibility of nonnegligible W electric dipole ( W ) and magnetic quadrupole (Q W ) moments induced by the most general HWW vertex is examined via the effective Lagrangian technique. It is assumed that new heavy fermions induce an anomalous CP-odd component of the HWW vertex, which can be parametrized by an SU L 2 U Y 1-invariant dimension-six operator. This anomalous contribution, when combined with the standard model CP-even contribution, leads to CP-odd electromagnetic properties of the W boson, which are characterized by the form factors and Q. It is found that is divergent, whereas Q is finite, which reflects the fact that the latter cannot be generated at the one-loop level in any renormalizable theory. Assuming reasonable values for the unknown parameters, we found that W 3 ÿ 6 10 ÿ21 e cm, which is 8 orders of magnitude larger than the SM prediction and close to the upper bound derived from the neutron electric dipole moment. The estimated size of the somewhat less-studiedQ W moment is of the order of ÿ10 ÿ36 e cm 2 , which is 15 orders of magnitude above the SM contribution.

CP-odd static electromagnetic properties of theWgauge boson and thetquark via the anomaloustHernández-Sanchez1, Honorato2, Procopio3 et al. 2007Phys. Rev. DSelf Cite9180View full textAdd to dashboardCite

“…It was shown that the most general HW W coupling, which includes both CP-even and CP-odd components, can give rise to both CP-odd W W γ form factorsκ andQ. The numerical estimates obtained for appropriate values of the unknown parameters are µ W ∼ 3 − 6 × 10 −20 e· cm and Q W ∼ −10 −36 e· cm 2 [28]. We thus can conclude that the values for µ W and Q W induced by the anomalous tbW coupling, which are about 7 and 17 orders of magnitude above their respective SM predictions, are one order of magnitude smaller that those generated by an anomalous HW W coupling.…”

“…Beyond the SM, most of the studies have focused on µ W , with the exception of Ref. [28], in which both µ W and Q W were estimated. In sharp contrast with the negligibly small SM predictions, some of its extensions predict values several orders of magnitude larger.…”

“…For instance, in Ref. [28] a general HW W coupling involving both CP-even and CP-odd components was considered, which gives rise to both µ W and Q W . Our results, obtained in the Higgsless EWCL scenario, are about one order of magnitude smaller than those induced in the scenario where at least one relatively light Higgs boson is present.…”

“…[28] within the context of the linear electroweak effective Lagrangian (LEWEL), which do assume the existence of the Higgs boson, in contrast with the EWCL. It was shown that the most general HW W coupling, which includes both CP-even and CP-odd components, can give rise to both CP-odd W W γ form factorsκ andQ.…”

Bilepton effects on theWWV*vertex in the 331 model with right-handed neutrinos via aSUL(2)×Ramírez–Zavaleta1, Tavares‐Velasco2, Toscano3 2007Phys. Rev. DSelf Cite23090View full textAdd to dashboardCite

“…Along these lines, in Ref. [1] we calculated the one-loop contributions to the W W V * vertex from the gauge sector of the so called minimal 331 model [15,16]. In order to construct a well-behaved gauge independent Green function, rather than using the PT, we invoked an alternative method inspired in the BFM and BRST symmetry [17], which is well suited to study the sensitivity of the W W V * vertex to the virtual effects of the new gauge bosons predicted by 331 models.…”