# A light sneutrino rescues the light stop

Journal of High Energy Physics, Apr 2017

Stop searches in supersymmetric frameworks with R-parity conservation usually assume the lightest neutralino to be the lightest supersymmetric particle. In this paper we consider an alternative scenario in which the left-handed tau sneutrino is lighter than neutralinos and stable at collider scales, but possibly unstable at cosmological scales. Moreover the (mostly right-handed) stop $\overset{\sim }{t}$ is lighter than all electroweakinos, and heavier than the scalars of the third generation lepton doublet, whose charged component, $\overset{\sim }{\tau }$, is heavier than the neutral one, $\overset{\sim }{\nu }$. The remaining supersymmetric particles are decoupled from the stop phenomenology. In most of the parameter space, the relevant stop decays are only into $t\overset{\sim }{\tau}\tau$, $t\overset{\sim }{\nu}\nu$ and $b\overset{\sim }{\nu}\tau$ via off-shell electroweakinos. We constrain the branching ratios of these decays by recasting the most sensitive stop searches. Due to the “double invisible” kinematics of the $\overset{\sim }{t}\to t\overset{\sim }{\nu}\nu$ process, and the low efficiency in tagging the $t\overset{\sim }{\tau}\tau$ decay products, light stops are generically allowed. In the minimal supersymmetric standard model with ∼ 100 GeV sneutrinos, stops with masses as small as ∼ 350 GeV turn out to be allowed at 95% CL.

This is a preview of a remote PDF: https://link.springer.com/content/pdf/10.1007%2FJHEP04%282017%29097.pdf

M. Chala, A. Delgado, G. Nardini, M. Quirós. A light sneutrino rescues the light stop, Journal of High Energy Physics, 2017, 97, DOI: 10.1007/JHEP04(2017)097