Collider Signals of Maximal Flavor Violation: Same-Sign Leptons from Same-Sign Tops at the Tevatron

Abstract

In models of maximal flavor violation (MxFV) there is at least one new scalar $Φ_{FV}$ which couples to the quarks via $Φ_{FV} q_i q_j \propto ξ_{ij}$ where $ξ_{i3},ξ_{3i} \sim V_{tb}$ for $i = 1,2$ and $ξ_{33} \sim V_{td}$ and $V$ is the CKM matrix. In this article, we explore the potential phenomenological implications of MxFV for collider experiments. We study MxFV signals of same-sign leptons from same-sign top-quark pair production at the Tevatron and at the LHC. We show that the current Tevatron dataset has strong sensitivity to this signature, for which there are no current limits. For example, if $m_{Φ_{FV}} \sim 200$ GeV and the MxFV coupling $ξ$ has a natural value of $\sim 1$, we expect $\sim 12$ MxFV events to survive a selection requiring a pair of same-sign leptons, a tagged $b$-jet and missing transverse energy, over a background of approximately 4-5 events.

Figures (3)

• Figure 1: Top: distribution in reconstructed jets with $E_T>15$ GeV for the signal process (each process is shown with unit area) with $m_{\eta^0}=200$ GeV/c$^2$ and after requiring same-sign leptons, 20 GeV of ${\not\!\! E_T}$ and at least one $b$-tagged jet. Bottom: expected number of reconstructed jets in 2 fb$^{-1}$ of data, for the signal processes with $\xi=1$ and backgrounds.
• Figure 2: Horizontal bands in fitted (measured) $\xi$ which include 95% of the results of Monte Carlo experiments, for varying values of true $\xi$, with $m_{\eta^0}=200$ GeV/c$^2$, following the prescription in feldcous. A 95% CL band in true $\xi$ for a given fit $\xi$ is a vertical band at the measured value (see text).
• Figure 3: Expected 95% CL allowed regions in the $\xi - m_{\eta^0}$ plane for 2 fb$^{-1}$ data. Top: for background-only hypothesis using $\xi=0$ in the Monte Carlo experiments. Bottom: for signal-plus-background hypothesis with $\xi=1$ in the Monte Carlo experiments, as explained in the text.