Resolving the A_{FB}^b puzzle in an extra dimensional model with an extended gauge structure

Abstract

It is notorious that, contrary to all other precision electroweak data, the forward-backward asymmetry for b quarks $A_{FB}^b$ measured in Z decays at LEP1 is nearly three standard deviations away from the predicted value in the Standard Model; significant deviations also occur in measurements of the asymmetry off the Z pole. We show that these discrepancies can be resolved in a variant of the Randall-Sundrum extra-dimensional model in which the gauge structure is extended to $SU(2{)}_L\times SU(2{)}_R\times U(1{)}_X$ to allow for relatively light Kaluza-Klein excitations of the gauge bosons. In this scenario, the fermions are localized differently along the extra dimension, in order to generate the fermion mass hierarchies, so that the electroweak interactions for the heavy third generation fermions are naturally different from the light fermion ones. We show that the mixing between the Z boson with the Kaluza-Klein excitations allows to explain the $A_{FB}^b$ anomaly without affecting (and even improving) the agreement of the other precision observables, including the $Z\to bb$ partial decay width, with experimental data. Some implications of this scenario for the ILC are summarized.

23 pages, 5 figures

References in corpus (5)

• A custodial symmetry for Zbb
• Probing the Randall-Sundrum geometric origin of flavor with lepton flavor violation
• Flavour physics of the RS model with KK masses reachable at LHC
• Two-Parton Contribution to the Heavy-Quark Forward-Backward Asymmetry in NNLO QCD
• Top Pair Production in Randall-Sundrum Models

Cited by in corpus (14)

• Flavor Physics in the Randall-Sundrum Model: I. Theoretical Setup and Electroweak Precision Tests
• Delta F=2 Observables and Fine-Tuning in a Warped Extra Dimension with Custodial Protection
• Minimal Flavor Protection: A New Flavor Paradigm in Warped Models
• Kaluza--Klein excitations of gauge bosons at the LHC
• Kaluza-Klein Gluons as a Diagnostic of Warped Models
• Searching for t-bar t Resonances at the Large Hadron Collider
• Higgs production at the LHC in warped extra-dimensional models
• Associated production of a Kaluza-Klein excitation of a gluon with a t t(bar) pair at the LHC
• Tests of non-standard electroweak couplings of right-handed quarks
• Probing RS scenarios of flavour at LHC via leptonic channels
• Multi-W Events at LHC from a Warped Extra Dimension with Custodial Symmetry
• Chiral-logarithmic Corrections to the S and T Parameters in Higgsless Models
• Unparticle Physics and A_{FB}^b on the Z pole
• K and B meson mixing in warped extra dimensions with custodial protection