Long life stau in the minimal supersymmetric standard model

Abstract

We study the stau lifetime in a scenario with the LSP taken to be a neutralino and the NLSP being a stau, based on the minimal supersymmetric Standard Model. The mass difference between the LSP and NLSP, $\delta m$, must satisfy $\delta m/m_{\tilde{\chi}} \sim$ a few % or less for coannihilation to occur, where $m_{\tilde{\chi}}$ is the neutralino mass. We calculate the stau lifetime from the decay modes $\tilde{\tau}\to \tilde{\chi}\tau$, $\tilde{\chi}\nu_\tau\pi$, and $\tilde{\chi}\nu_\tau\mu(e)\nu_{\mu(e)}$ and discuss its dependence on various parameters. We find that the lifetime is in the range $10^{-22}$--$10^{16}$ sec for $10^{-2} \le \delta m \le 10$ GeV. We also discuss the connection with lepton flavor violation if there is mixing between sleptons.Comment: 15 pages, 5 figure

Light neutralino dark matter: direct/indirect detection and collider searches

“…For a light sbottom and stau, the cross sections at 250 GeV ILC are about 130 fb and 400 fb, respectively, while the cross sections at 500 ILC are about a factor of four smaller. For the stau pair production, the mass splitting ∆m ≥ m τ would yield the prompt decay ofτ → τχ 0 1 with a typical lifetime of 10 −22 − 10 −19 second [188]. The parent stau momentum and the energy range of the decay product τ are, respectively,…”

Big-bang nucleosynthesis with a long-lived charged massive particle includingHe4spallation processes

“…Such long-lived staus will be copious during the BBN [50,51], we have shown in [29,33,38] that their presence indeed alters the prediction of the standard BBN and possibly solves the discrepancy of the lithium abundance in the Universe through the internal conversion reactions.…”

Simplified models for exotic BSM searches

“…A similar situation might occur in models of extra dimensions [5]. Other supersymmetric scenarios with mass degenerate sparticles have been proposed in order to address the discrepancy between the 6 Li, 7 Li abundances predicted in standard big bang nucleosynthesis (BBN) and those inferred from astrophysical observations [6]. In this scenario a bino-like neutralino and the lightest charged slepton are close in mass, resulting in a long-lived slepton [7].…”

“…Other supersymmetric scenarios with mass degenerate sparticles have been proposed in order to address the discrepancy between the 6 Li, 7 Li abundances predicted in standard big bang nucleosynthesis (BBN) and those inferred from astrophysical observations [6]. In this scenario a bino-like neutralino and the lightest charged slepton are close in mass, resulting in a long-lived slepton [7]. Another possible scenario leading to HSCPs corresponds to the case where the LOP does not share the SM gauge couplings and only interacts super weakly.…”