Top quark forward-backward asymmetry from new<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>t</mml:mi></mml:math>-channel physics

Abstract

Motivated by recent measurements of the top quark forward-backward asymmetry\nat the Tevatron, we study how t-channel new physics can contribute to a large\nvalue. We concentrate on a theory with an abelian gauge boson possessing flavor\nchanging couplings between up and top quarks, but satisfies flavor physics\nconstraints. Collider constraints are strong, but can be consistent with the\naid of small flavor diagonal couplings. We find that M_Z' ~ 160 GeV can yield a\ntotal lab-frame asymmetry of ~18% without being in conflict with other\nobservables. There are implications for future collider searches, including\nexotic top quark decays, like-sign top quark production, and detailed\nmeasurements of the top production cross section. An alternate model with a\ngauged non-Abelian flavor symmetry would have similar phenomenology, but lacks\nthe like-sign top signal.\n