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Top-quark forward-backward asymmetry in Randall-Sundrum models beyond the leading order

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Abstract

We calculate the \( t\overline t \) forward-backward asymmetry, A t FB, in Randall-Sundrum (RS) models taking into account the dominant next-to-leading order (NLO) corrections in QCD. At Born level we include the exchange of Kaluza-Klein (KK) gluons and photons, the Z boson and its KK excitations, as well as the Higgs boson, whereas beyond the leading order (LO) we consider the interference of tree-level KK-gluon exchange with one-loop QCD box diagrams and the corresponding bremsstrahlungs corrections. We find that the strong suppression of LO effects, that arises due to the elementary nature and the mostly vector-like couplings of light quarks, is lifted at NLO after paying the price of an additional factor of α s /(4π). In spite of this enhancement, the resulting RS corrections in A t FB remain marginal, leaving the predicted asymmetry SM-like. As our arguments are solely based on the smallness of the axial-vector couplings of light quarks to the strong sector, our findings are model-independent and apply to many scenarios of new physics that address the flavor problem via geometrical sequestering.

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  1. Institut für Physik (THEP), Johannes Gutenberg-Universität, D-55099, Mainz, Germany

    M. Bauer, F. Goertz, U. Haisch, T. Pfoh & S. Westhoff

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Bauer, M., Goertz, F., Haisch, U. et al. Top-quark forward-backward asymmetry in Randall-Sundrum models beyond the leading order. J. High Energ. Phys. 2010, 39 (2010). https://doi.org/10.1007/JHEP11(2010)039

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