Stop and Sbottom Searches in Run II of the Fermilab Tevatron

TL;DR

The paper assesses Tevatron Run II prospects for discovering or constraining light stops and sbottoms across a range of SUSY scenarios. Using detailed Monte Carlo simulations of collider events and the upgraded CDF detector performance, it evaluates multiple decay channels, including $\tilde{t}\rightarrow \tilde{\chi}^+_1 b$, $\tilde{t}\rightarrow \tilde{\chi}^0_1 c$, and $\tilde{t}\rightarrow \tilde{\nu} \ell^+ b$, under mSUGRA and beyond (non-universal scalars, higgsino LSP, and gauge-mediated models). The results map Run II mass reachs as functions of luminosity and model parameters, highlighting how heavy-flavor tagging, missing $E_T$, and kinematic selections extend sensitivity beyond LEP limits in many channels, while certain higgsino- or NLSP-dominated scenarios may require alternative production or decay signatures. Overall, the work provides a comprehensive set of search strategies and projected reaches that inform SUSY coverage at the Tevatron Run II and guide experimental analyses across diverse SUSY-breaking schemes.

Abstract

We estimate the Tevatron Run II potential for top and bottom squark searches. We find an impressive reach in several of the possible discovery channels. We also study some new channels which may arise in non-conventional supersymmetry models. In each case we rely on a detailed Monte Carlo simulation of the collider events and the CDF detector performance in Run I.

Figures (10)

• Figure 1: Contours of the light stop mass $m_{\tilde{t}}$ (in GeV), versus the mixing parameter $a_0$ and $\tan\beta$, for $M_{1/2}=300$ GeV, $M_0=300$ GeV and $\mu>0$. Inside the light-shaded region there is a scalar (stop, stau or CP-odd Higgs) which is too light or tachyonic. The dark-shaded region is theoretically allowed, but ruled out because of the CP-even Higgs mass limit of $m_h>95$ GeV.
• Figure 2: Contours of the light Higgs mass $m_h$ (in GeV) for the same parameters as in Fig. \ref{['mstop']}.
• Figure 3: Contours of the light stop mass $M_h$ (in GeV) in the $M_0-A_0$ plane, for fixed $M_{1/2}=300$ GeV, $\tan\beta=10$ and $\mu>0$.
• Figure 4: Typical values of efficiencies after final cuts for the stop signatures considered in the text.
• Figure 5: Sensitivity of the light stop search in the $b\ell j {\hbox{,/}E_T}$ channel for several integrated luminosities. The analysis assumes 100% branching ratio for $\tilde{t}\rightarrow b \tilde{\chi}^+_1$ and $W$-like branching ratios for the chargino decays.