Metastable Charged Sparticles and the Cosmological Li7 Problem

Cyburt, Richard H.; Olive, Keith A.; Spanos, Vassilis C.; Luo, Feng; Ellis, John; Fields, Brian D.

doi:10.1088/1475-7516/2012/12/037

Article
Report number	arXiv:1209.1347 ; KCL-PH-TH-2012-36 ; LCTS-2012-18 ; CERN-PH-TH-2012-223 ; FTPI-MINN-12-29 ; UMN-TH-3117-12 ; KCL-PH-TH-2012-36 ; LCTS-2012-18 ; CERN-PH-TH-2012-223 ; UMN-TH-3117-12 ; FTPI-MINN-12-29
Title	Metastable Charged Sparticles and the Cosmological Li7 Problem
Author(s)	Cyburt, Richard H. (Michigan State U. ; Michigan State U., NSCL ; Michigan State U., JINA) ; Ellis, John (CERN ; King's Coll. London) ; Fields, Brian D. (Illinois U., Urbana, Astron. Dept.) ; Luo, Feng (Minnesota U. ; King's Coll. London) ; Olive, Keith A. (Minnesota U., Theor. Phys. Inst. ; Minnesota U.) ; Spanos, Vassilis C. (Democritos Nucl. Res. Ctr.)
Publication	2012
Imprint	07 Sep 2012
Number of pages	49
Note	Comments: 49 pages, 29 eps figures 49 pages, 29 eps figures
In:	JCAP 12 (2012) 037
DOI	10.1088/1475-7516/2012/12/037
Subject category	Astrophysics and Astronomy
Abstract	We consider the effects of metastable charged sparticles on Big-Bang Nucleosynthesis (BBN), including bound-state reaction rates and chemical effects. We make a new analysis of the bound states of negatively-charged massive particles with the light nuclei most prominent in BBN, and present a new code to track their abundances, paying particular attention to that of Li7. Assuming, as an example, that the gravitino is the lightest supersymmetric particle (LSP), and that the lighter stau slepton, stau_1, is the metastable next-to-lightest sparticle within the constrained minimal supersymmetric extension of the Standard Model (CMSSM), we analyze the possible effects on the standard BBN abundances of stau_1 bound states and decays for representative values of the gravitino mass. Taking into account the constraint on the CMSSM parameter space imposed by the discovery of the Higgs boson at the LHC, we delineate regions in which the fit to the measured light-element abundances is as good as in standard BBN. We also identify regions of the CMSSM parameter space in which the bound state properties, chemistry and decays of metastable charged sparticles can solve the cosmological Li7 problem.
Copyright/License	Preprint: © 2012-2025 CERN (License: CC-BY-3.0)

$noimg\it Properties of $X^-$ bound states with relevant nuclides. The Table lists relevant nuclides together with their (unbound) masses and rms charge radii $R_{\rm c}$ in Coulombic parameterizations of the potentials. Bound-state binding energies $B_A$ come from our 2-body calculations based on the given charge radii (except where otherwise noted). Experimental values and ranges of $R_{\rm c}$ are listed, where available for some nuclides, and ranges of theoretical estimates of $R_{\rm c}$ for other nuclides.$ $\it Level schemes calculated for unbound and bound $X^-$ states in the \be9 system. State labels appear above the corresponding level. Level values shown are based on Table 1, and all levels are shifted such that zero energy corresponds to the free-particle state. In the case of $(\be8X^-)$, we show the result of our 3-body calculation (a blue band whose the width corresponds to the uncertainty), as well as the 2-body calculations of Kamimura {\it et al.}~\cite{Kamimura09} and of Pospelov~\cite{Pospelov07} (labelled). In the case of $(\be9^*X^-)$, we consider a range of level values including our and Pospelov's estimates.$ $\it The abundances of free nuclei (dashed lines) and nuclear bound states (solid lines) as functions of temperature. The black line corresponding to the abundance of free $X^-$ particles, which is assumed to be $10^{-2}$ initially. In this case the $X$ lifetime $\tau_{X}$ is assumed to be infinite.$ Show more plots

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Record created 2012-09-07, last modified 2023-11-03

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