Abstract
Understanding the extent to which experimental searches are sensitive to Light Stops (LST) scenarios is essential to resolve questions about naturalness, electroweak baryogenesis and Dark Matter. In this paper we characterize the reach on LST scenarios in two ways. We extend experimental searches to cover specific gaps in the LST parameter space, showing for the first time that assuming a single decay channel one can exclude the region of $m_{\tilde{t}}<m_{top}$, which in its turn excludes electroweak baryogenesis in MSSM. Also, we explore the extent to which searches are weakened in a more generic scenario when more than one decay channel takes place, even after their combination. This study highlights the need for a more comprehensive exploration of the LST parameter space.
Highlights
SUSY naturalness which suggests that the third generation squarks should be below about 1 TeV [9, 10]
We extend experimental searches to cover specific gaps in the Light Stops (LST) parameter space, showing for the first time that assuming a single decay channel one can exclude the region of mt < mtop, which in its turn excludes electroweak baryogenesis in MSSM
It has been shown that the usual fine-tuning measures, defined as the sensitivity of the weak scale to fractional variations in the fundamental parameters of the theory, can be low even if the masses of the supersymmetric scalars are large. This happens in the so called “hyperbolic branch”(HB) [11] or “focus point” (FP) [12,13,14] regions of the minimal super gravity parameter space, where the value of the Higgs mass parameter, μ, can be low if the universal gaugino mass M1/2 is not too large. It was recently argued [15] that EW fine-tuning in SUSY scenarios can be grossly overestimated by neglecting additional terms, stemming from the ultra violet (UV) completion of the model, that can lead to large cancellations favouring a low μ-parameter and allowing a heavier stop mass
Summary
SUSY naturalness which suggests that the third generation squarks should be below about 1 TeV [9, 10]. It has been shown that the usual fine-tuning measures, defined as the sensitivity of the weak scale to fractional variations in the fundamental parameters of the theory, can be low even if the masses of the supersymmetric scalars are large This happens in the so called “hyperbolic branch”(HB) [11] or “focus point” (FP) [12,13,14] regions of the minimal super gravity (mSUGRA) parameter space, where the value of the Higgs mass parameter, μ, can be low if the universal gaugino mass M1/2 is not too large. One can see that the answer to the question of what is the lower stop mass limit is crucial for different aspects of Supersymmetry — one of the most appealing BSM theo-
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