Search for Maximal Flavor Violating Scalars in Same-Charge Lepton Pairs in $p\bar{p}$ Collisions at $\sqrt{s} = 1.96$ TeV

Abstract

Models of Maximal Flavor Violation (MxFV) in elementary particle physics may contain at least one new scalar SU$(2)$ doublet field $Φ_{FV} = (η^0,η^+)$ that couples the first and third generation quarks ($q_1,q_3$) via a Lagrangian term $\mathcal{L}_{FV} = ξ_{13} Φ_{FV} q_1 q_3$. These models have a distinctive signature of same-charge top-quark pairs and evade flavor-changing limits from meson mixing measurements. Data corresponding to 2 fb$^{-1}$ collected by the CDF II detector in $p\bar{p}$ collisions at $\sqrt{s} = 1.96$ TeV are analyzed for evidence of the MxFV signature. For a neutral scalar $η^0$ with $m_{η^0} = 200$ GeV/$c^2$ and coupling $ξ_{13}=1$, $\sim$ 11 signal events are expected over a background of $2.1 \pm 1.8$ events. Three events are observed in the data, consistent with background expectations, and limits are set on the coupling $ξ_{13}$ for $m_{η^0} = 180-300$ GeV/$c^2$.