On the ATLAS Top Mass Measurements and the Potential for Stealth Stop Contamination

• Main Authors: Cohen, Timothy, Majewski, Stephanie, Ostdiek, Bryan, Zheng, Peter
• Format: Journal Article
• Language: English
• Published: 04-06-2020
• Subjects: Physics - High Energy Physics - Experiment; Physics - High Energy Physics - Phenomenology
• DOI: 10.48550/arxiv.1909.09670

The discovery of the stop - the Supersymmetric partner of the top quark - is
a key goal of the physics program enabled by the Large Hadron Collider.
Although much of the accessible parameter space has already been probed, all
current searches assume the top mass is known. This is relevant for the
"stealth stop" regime, which is characterized by decay kinematics that force
the final state top quark off its mass shell; such decays would contaminate the
top mass measurements. We investigate the resulting bias imparted to the
template method based ATLAS approach. A careful recasting of these results
shows that effect can be as large as 2.0 GeV, comparable to the current quoted
uncertainty on the top mass. Thus, a robust exploration of the stealth stop
splinter requires the simultaneous consideration of the impact on the top mass.
Additionally, we explore the robustness of the template technique, and point
out a simple strategy for improving the methodology implemented for the
semi-leptonic channel.