Right-handed slepton bulk regions for dark matter in a generalized minimal supergravity

We study the light right-handed slepton bulk regions for dark matter from the generalized minimal supergravity (GmSUGRA) in the minimal supersymmetric Standard Model. In our comprehensive numerical studies, we show that ${\mathcal{R}}_{\tilde{\varphi }}\gtrsim 10\%$ is a conservative criterion to formulate bulk region, where ${\mathcal{R}}_{\tilde{\varphi }}\equiv (m_{\tilde{\varphi }}-m_{{\tilde{\chi }}_1^0})/m_{{\tilde{\chi }}_1^0}$. For right-handed stau as the next-to-the-lightest supersymmetric particle (NLSP), we find a large viable parameter space, consistent with the current LHC constraints, Planck2018 dark matter relic density bounds, and direct bounds on neutralino-nucleons scattering cross section that naturally supports the right-handed stau bulk regions for dark matter. In particular, the upper bounds on the masses of the lightest supersymmetric particle neutralino and right-handed stau are about 120.4 and 138 GeV, respectively. This bulk region may be beyond the current LHC reach and could be probed at LUX-ZEPLIN, a next-generation dark matter direct-detection experiment, the Future Circular Collider at CERN, and the Circular Electron Positron Collider. However, the scenario with the right-handed selectron as the NLSP is excluded by the LHC supersymmetry searches.

Figure 1

Gray points satisfy the REWSB and yield LSP neutralino. Orange, brown, and red points are the subset of gray points that satisfy LEP bounds, B-physics bounds, Higgs bound, and sparticles LHC constraints. Also, orange, brown, and red points, respectively, correspond to oversaturated, undersaturated, and saturated DM relic density. In the panel, ${\mathcal{R}}_{{\tilde{\tau }}_1}\equiv (m_{{\tilde{\tau }}_1}-m_{{\tilde{\chi }}_1^0})/m_{{\tilde{\chi }}_1^0}$.

Figure 2

Gray points satisfy the REWSB and yield LSP neutralino. Orange, brown, and red points are the subset of gray points that satisfy LEP bounds, B-physics bounds, Higgs bound, and sparticles LHC constraints. Also, orange, brown, and red points, respectively, correspond to oversaturated, undersaturated, and saturated DM relic density with ${\mathcal{R}}_{{\tilde{\tau }}_1}\gtrsim 10\%$.

Figure 3

Gray points satisfy the REWSB and yield LSP neutralino. Orange, brown, and red points are the subset of gray points that satisfy LEP bounds, B-physics bounds, Higgs bound, and sparticles LHC constraints. Also, orange, brown, and red points, respectively, correspond to oversaturated, undersaturated, and saturated DM relic density with ${\mathcal{R}}_{{\tilde{\tau }}_1}\gtrsim 10\%$. The black line shows the central value of $\mathrm{\Delta }{a}_{\mu }$ and the green and brown lines, respectively, represent $1\sigma$ and $2\sigma$ deviation from the central value.

Figure 4

The bulk region from the GmSUGRA superimposed over the August 2023 ATLAS SUSY updated summary plots [46] for the electroweak production of sleptons [43, 47, 48, 54, 55]. The blue point corresponds to the first two generation diright sleptons [a degenerate right-handed selectron (${\tilde{e}}_R$) and smuon (${\tilde{\mu }}_R$)] while green points correspond to distau (${\tilde{\tau }}_1$) in the GmSUGRA. All points are annihilation only, adhere to our requirement ${\mathcal{R}}_{{\tilde{\tau }}_1}\gtrsim 10\%$, and satisfy the saturated DM relic density. Note that the ATLAS orange-shaded region applies to the first two family sleptons [selection (${\tilde{e}}_{L,R}$) and smuon (${\tilde{\mu }}_{L,R}$)] only, not to stau (${\tilde{\tau }}_1$). The ${\tilde{\tau }}_1$ constraints are the green-shaded region in the ATLAS, and the GmSUGRA points are comfortably beyond.

Figure 5

Gray points satisfy the REWSB and yield LSP neutralino. Orange, brown, and red points are the subset of gray points that satisfy LEP bounds, B-physics bounds, Higgs bound, and sparticles LHC constraints. Also, orange, brown, and red points, respectively, correspond to oversaturated, undersaturated, and saturated DM relic density with ${\mathcal{R}}_{{\tilde{\tau }}_1}\gtrsim 10\%$. The spin-independent (top) and spin-dependent (bottom) neutralino-proton scattering cross section vs the neutralino mass in reference from current direct-detection experiments, such as XENONnT (solid black line) [56] and LUX-ZEPLIN [solid green line LZ(2022)]. Also with LZ-1000 day sensitivity (solid blue line) [57, 58].