Searching SUSY Leptonic Partner at the CERN LHC

Abstract

Motivated by the observed excess of the di-photon signal in Higgs searches, ${\sigma }_{\gamma \gamma }/{\sigma }_{\mathrm{SM}}\simeq 1.5$, we argue that models with enhanced $\Gamma (h\to \gamma \gamma )$ alone are the most favorable scenarios when the latest LHC/Tevatron results are all taken into account. We study the phenomenology of a supersymmetric scenario of light stau first proposed by \textit{Carena et. al. \cite{carlos}} that predicts a 125 GeV SM-like Higgs boson with enhanced diphoton decay through light stau loops. Since it is extremely challenging to search the Drell-Yan stau pair at the LHC due to the small production rate, we focus on the parameter space with enhanced production of inclusive stau pairs, in particular, via $b\bar{b}$ fusion or gaugino pairs. We study its phenomenology in both pure leptonic tau ${\tau }_{\ell }^{\pm }$ channels and hadronic tau tagged ${\tau }_h$ channels. We find the same-sign dilepton from ${\tilde{\chi }}_1^{\pm }{\tilde{\chi }}_2^0\to {\tau }_{\ell }^{\pm }{\tau }_{\ell }^{\pm }+X$ may significantly improve the discovery potential with even 7--8 TeV LHC of $\mathcal{O}(30{\text{fb}}^{-1})$ data. In the case of hadronic tau pair, we use the final state $j+{\tau }_h{\tau }_h+{\cancel{E}}_T$ to search and find that even with the most optimistic region of $M_2\sim 200-300$ GeV, it requires at least 50 fb${}^{-1}$ data of 14 TeV LHC to reach a significance of 3.5 $\sigma$. Therefore, we conclude it is difficult to claim discovery only through hadronic tau based on the data by the 2012 shut-down. 5 $\sigma$ reach for our most optimistic region then requires 100 fb${}^{-1}$ data with 14 TeV running.

Comments: 18 pages, 8 figures, version accepted by Physics Letter B