Gluino mass limits with sbottom NLSP in coannihilation scenarios

TL;DR

This paper explores a supersymmetric scenario where the lightest bottom squark is the NLSP co-annihilating with the LSP, analyzing its implications for dark matter and deriving new gluino mass limits from LHC data.

Contribution

It introduces a novel sbottom NLSP co-annihilation scenario with specific mass differences, and derives new experimental limits on gluino masses within this framework.

Findings

Large NLSP-LSP mass difference (25-35 GeV) consistent with PLANCK data.

Identification of unique signals like $ ilde{t}_1 ightarrow ilde{b}_1 W$ not viable in stop NLSP scenarios.

Gluino mass limits of 1.1-1.2 TeV for sbottom masses up to 500 GeV.

Abstract

In view of the recent interest in the pMSSM with light third generation squarks, we consider a hitherto neglected scenario where the lighter bottom squark ($\widetilde{b}_1$) is the next lightest supersymmetric particle (NLSP) which co-annihilates with the lightest supersymmetric particle (LSP), the dark matter (DM) candidate. Since the co-annihilation cross section receives contributions from both electroweak and strong vertices, it is relatively large. As a result relatively large NLSP-LSP mass difference (25 - 35 GeV) is consistent with the PLANCK data. This facilitates the LHC signatures of this scenario. We consider several variants of the sbottom NLSP scenario with and without light stops and delineate the parameter space allowed by the PLANCK data. We point out several novel signal (e.g., $\widetilde{t}_1 \rightarrow \widetilde{b}_1 W$) which are not viable in the stop NLSP scenario of DM production. Finally, we consider gluino ($\widetilde g$) decays in this scenario and using the current ATLAS data in the jets (with or without b-tagging) + $\not \!\! E_T$ channel, obtain new limits in the $m_{\widetilde{b}_1} - m_{\widetilde g}$ mass plane. We find that for $m_{\widetilde{b}_1}$ upto 500 GeV, $m_{\widetilde g} \geq$ 1.1 - 1.2 TeV in this scenario.