I am using
\usepackage{xltxtra}
\setmainfont[Mapping=tex-text]{Ubuntu}
to change the "text" font in my latex document. However this has messed up some math equations and things like
\mathbf{E} \exp \sin \cos
are also displayed using the font for the text which makes it look ugly and inconsistent with the rest of equation.
Is there a way to fix this so that the above specified font is only used for text and not anywhere in the equations?