Scalar Top Mass Research Articles

Search for lepton flavour violation in the eμ continuum with the ATLAS detector in [Formula: see text]pp collisions at the LHC.

This paper presents a search for the t-channel exchange of an R-parity violating scalar top quark (tilde{t}) in the e±μ∓ continuum using 2.1 fb−1 of data collected by the ATLAS detector in sqrt{s}=7~mbox{TeV}pp collisions at the Large Hadron Collider. Data are found to be consistent with the expectation from the Standard Model backgrounds. Limits on R-parity-violating couplings at 95 % C.L. are calculated as a function of the scalar top mass (m_{tilde{t}}). The upper limits on the production cross section for pp→eμX, through the t-channel exchange of a scalar top quark, ranges from 170 fb for m_{tilde{t}}=95~mbox{GeV} to 30 fb for m_{tilde{t}}=1000~mbox{GeV}.

Can the supersymmetric flavor problem be solved by decoupling?

It has been argued that the squarks and sleptons of the first and second generations can be relatively heavy without destabilizing the weak scale, thereby improving the situation with too-large flavor-changing neutral current (FCNC) and CP violating processes. In theories where the soft supersymmetry breaking parameters are generated at a high scale (such as the Planck scale), we show that such a mass spectrum tends to drive the scalar top mass squared $m_{\tilde{Q}_3}^2$ negative from two-loop renormalization group evolution. Even ignoring CP violation and allowing $O(\lambda) \sim .22$ alignment, the first two generation scalars must be heavier than 22 TeV to suppress FCNC. This in turn requires the boundary condition on $m_{\tilde{Q}_3} > 4 TeV$ to avoid negative $m_{\tilde{Q}_3}^2$ at the weak scale. Some of the models in the literature employing the anomalous U(1) in string theory are excluded by our analysis.

Light scalar top squark in the minimal supersymmetric grand unified theory.

We point out that a light scalar top squark with mass as small as [ital m][sub [ital [tilde t]]][approx]20 GeV is still an allowed possibility within the standard, minimal supersymmetry grand unified theory, if the photino exists at mass slightly below the scalar top mass, so that coannihilation efficiently takes place for [tilde [gamma]][tilde [gamma]][r arrow][ital gg] in the early Universe. We show that this case, receiving a number of strong phenomenological constraints, leads to a restricted pattern of the mass spectrum of other supersymmetry particles.