Can someone tell me what LaTeX typeface this is?

Question

It's the font used for the examples on the Texpad website, it's not one of the default fonts, but I can't seem to find what it is. I'm hoping someone would recognise it, thanks.

Answer 1

I'm pretty sure it is Kepler (aka kpfonts). For some more verification compare the following output to the first image in your question.

\documentclass{article}
\linespread{1.5}
\usepackage{kpfonts}
\usepackage{mathtools}
\begin{document}
\noindent
The lack of Weyl classical invariance may be compensated by one-loop
contributions arising from couplings to $G_{\mu\nu}$ and
$B_{\mu\nu}$. The beta functions associated with $G_{\mu\nu}$,
$B_{\mu\nu}$ and $\phi(X)$ at the one loop level are
\begin{align}
  \beta_{\mu\nu}(G) &= \alpha' R_{\mu\nu} + 2 \alpha' \nabla_\mu \nabla_\nu \phi
  + \frac{\alpha'}{4} H_{\mu\lambda\rho} H_\nu^{\lambda\rho} \\
  \beta_{\mu\nu}(B) &= - \frac{\alpha'}{2} \nabla^\lambda H_{\lambda\mu\nu}
  + \alpha' \nabla^\lambda \phi H_{\lambda\mu\nu} \\
  \beta(\phi) &= \frac{D-26}{6} - \frac{\alpha'}{2} \nabla^2 \phi
  + \alpha' \nabla^\mu \phi \nabla_\mu \phi - \frac{\alpha'}{24} H_{\lambda\mu\nu} H^{\lambda\mu\nu}
\end{align}
\end{document}