\documentclass[11pt]{article}

\input{util/packages}
\input{util/tikz}

\begin{document}
\begin{stochasticModel}[2.5cm]
\node[state] (a)                    {$a$};
\node[state] (b) [above right of=a] {$b$};
\node[state] (c) [below right of=a] {$c$};


\node[dist]  (a_alpha) [right of=a, xshift=-1.6cm] {};
\path[] (a) edge [action] node {$\alpha$} (a_alpha)
        (a_alpha) edge [transition,sloped,below] node {$0.2$} (b)
        (a_alpha) edge [transition] node {$0.8$} (c);

\node[dist]  (b_alpha) [right of=b, xshift=-1.5cm] {};
\path[] (b) edge [action] node {$\alpha$} (b_alpha)
        (b_alpha) edge [transition,sloped,above,bend right=100,pos=0.35] node {$0.2$} (a)
        (b_alpha) edge [transition,below,pos=0.1,in=-110, out=-70,looseness=2] node[rotate=180] {$0.8$} (c);

\end{stochasticModel}

\end{document}