On the sign of the real part of the Riemann zeta-function

We consider the distribution of $\arg\zeta(\sigma+it)$ on fixed lines $\sigma > \frac12$, and in particular the density [d(\sigma) = \lim{T \rightarrow +\infty} \frac{1}{2T} |{t \in [-T,+T]: |\arg\zeta(\sigma+it)| > \pi/2}|\,,] and the closely related density [d{-}(\sigma) = \lim{T \rightarrow +\infty} \frac{1}{2T} |{t \in [-T,+T]: \Re\zeta(\sigma+it) < 0}|\,.] Using classical results of Bohr and Jessen, we obtain an explicit expression for the characteristic function $\psi\sigma(x)$ associated with $\arg\zeta(\sigma+it)$. We give explicit expressions for $d(\sigma)$ and $d{-}(\sigma)$ in terms of $\psi\sigma(x)$. Finally, we give a practical algorithm for evaluating these expressions to obtain accurate numerical values of $d(\sigma)$ and $d_{-}(\sigma)$.