Jan 2014 - Sep 2014

Boosting stop searches with boosted di-boson

by Diptimoy Ghosh

OC218 (Ogden Centre)


Ogden Centre

The lighter mass eigenstate ($\widetilde{t}_1$) of the two top squarks, the scalar superpartners of the top quark, is extremely difficult to discover if it is almost degenerate with the lightest neutralino ($\widetilde{\chi}_1^0$). The current experimental bound on $\widetilde{t}_1$ mass in this scenario stands only around 250 GeV. For such a light $\widetilde{t}_1$, the heavier top squark ($\widetilde{t}_2$) can also be around the TeV scale. I will argue that in such an MSSM scenario, because of the high value of the measured higgs mass, $\widetilde{t}_2$ is expected to have considerable branching ratios in the two channels $\widetilde{t}_2 \to \widetilde{t}_1 h$ and $\widetilde{t}_2 \to \widetilde{t}_1 Z$. This leads to a spectacular di-boson + missing transverse energy final state which can also be used to probe the $\widetilde{t}_1 - \widetilde{\chi}_1^0$ coannihilation region of the MSSM parameter space. Moreover, the $h$ and/or the $Z$ bosons can be sufficiently energetic if the $\widetilde{t}_1$ is light enough allowing the use of jet substructure technique to dig them out from the SM background.