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      New Nuclear Physics for Big Bang Nucleosynthesis

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          Abstract

          We discuss nuclear reactions which could play a role in Big Bang Nucleosynthesis (BBN). Most of these reactions involve lithium and beryllium isotopes and the rates for some of these have not previously been included in BBN calculations. Few of these reactions are well studied in the laboratory. We also discuss novel effects in these reactions, including thermal population of nuclear target states, resonant enhancement, and non-thermal neutron reaction products. We perform sensitivity studies which show that even given considerable nuclear physics uncertainties, most of these nuclear reactions have minimal leverage on the standard BBN abundance yields of 6Li and 7Li. Although a few have the potential to alter the yields significantly, we argue that this is unlikely.

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          Big-Bang Nucleosynthesis and Gravitino

          We derive big-bang nucleosynthesis (BBN) constraints on both unstable and stable gravitino taking account of recent progresses in theoretical study of the BBN processes as well as observations of primordial light-element abundances. In the case of unstable gravitino, we set the upper limit on the reheating temperature assuming that the primordial gravitinos are mainly produced by the scattering processes of thermal particles. For stable gravitino, we consider Bino, stau and sneutrino as the next-to-the-lightest supersymmetric particle and obtain constraints on their properties. Compared with the previous works, we improved the following points: (i) we use the most recent observational data, (ii) for gravitino production, we include contribution of the longitudinal component, and (iii) for the case with unstable long-lived stau, we estimate the bound-state effect of stau accurately by solving the Boltzmann equation.
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            Particle physics catalysis of thermal Big Bang Nucleosynthesis

            We point out that the existence of metastable, tau > 10^3 s, negatively charged electroweak-scale particles (X^-) alters the predictions for lithium and other primordial elemental abundances for A>4 via the formation of bound states with nuclei during BBN. In particular, we show that the bound states of X^- with helium, formed at temperatures of about T=10^8K, lead to the catalytic enhancement of Li6 production, which is eight orders of magnitude more efficient than the standard channel. In particle physics models where subsequent decay of X^- does not lead to large non-thermal BBN effects, this directly translates to the level of sensitivity to the number density of long-lived X^-, particles (\tau>10^5 s) relative to entropy of n_{X^-}/s < 3\times 10^{-17}, which is one of the most stringent probes of electroweak scale remnants known to date.
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              Big Bang Nucleosynthesis with Long Lived Charged Massive Particles

              We consider Big Bang Nucleosynthesis (BBN) with long lived charged massive particles. Before decaying, the long lived charged particle recombines with a light element to form a bound state like a hydrogen atom. This effect modifies the nuclear reaction rates during the BBN epoch through the modifications of the Coulomb field and the kinematics of the captured light elements, which can change the light element abundances. It is possible that the heavier nuclei abundances such as \(^7\)Li and \(^7\)Be decrease sizably, while the ratios \(Y_p\), D/H, and \(^3\)He/H remain unchanged. This may solve the current discrepancy between the BBN prediction and the observed abundance of \(^7\)Li. If future collider experiments found signals of a long-lived charged particle inside the detector, the information of its lifetime and decay properties could provide insights to understand not only the particle physics models but also the phenomena in the early universe in turn.
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                Author and article information

                Journal
                04 August 2010
                Article
                10.1103/PhysRevD.82.105005
                1008.0848

                http://arxiv.org/licenses/nonexclusive-distrib/1.0/

                Custom metadata
                Phys.Rev.D82:105005,2010
                13 pages, 6 figures
                astro-ph.CO hep-ph nucl-ex nucl-th

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