Big-bang nucleosynthesis reactions catalyzed by a long-lived negatively charged leptonic particle

An accurate quantum three-body calculation is performed for the new type of big-bang nucleosynthesis (BBN) reactions that are catalyzed by a hypothetical long-lived negatively charged, massive leptonic particle (called X-) such as the supersymmetric (SUSY) particle stau, the scalar partner of the tau lepton. It is known that if the X- particle has a lifetime τX> or approx. 103 s, it can capture a light element previously synthesized in standard BBN and form a Coulombic bound state, for example, (7BeX-) at temperature T9< or approx. 0.4 (in units of 109 K), (αX-) at T9< or approx. 0.1 and (pX-) at T9< or approx. 0.01. The bound state, an exotic atom, is expected to induce the following reactions in which X- acts as a catalyst: 1) α-transfer reactions such as (αX-)+d → 6Li+X, 2) radiative capture reactions such as (7BeX-)+p → (8BX-)+γ, 3) three-body breakup reactions such as (7LiX-)+p → α+α+X-, 4) charge-exchange reactions such as (pX-) + α → (αX-)+p and 5) neutron induced reactions such as (8BeX-) +n → 9Be+X-. In recent papers it has been claimed that some of these X--catalyzed reactions have significantly large cross sections so that the inclusion of the reactions into the BBN network calculation can markedly change the abundances of some elements, giving not only a solution to the 6Li-7Li problem (the calculated underproduction of 6Li by a factor of ∼1000 and overproduction of 7Li+7Be by a factor of ∼3) but also a constraint on the lifetime and primordial abundance of the elementary particle X-. However, most of these calculations of the reaction cross sections in the literature were performed assuming too naive models or approximations that are unsuitable for these complicated low-energy nuclear reactions. We use a high-accuracy few-body calculation method developed by the authors and provide precise cross sections and rates of these catalyzed BBN reactions for use in the BBN network calculation. (author)