[Tex/LaTex] Italic Helvetica font in Beamer

Question

How can an italic print of the font helvetica be achieved in the Beamer class?

Here is my MWE:

\documentclass[a4paper,11pt,fleqn]{beamer}
\usepackage[ngerman,english]{babel} % language listed last is default setting
\usepackage{fontspec} % load 'fontspec' when using XeLaTeX or LuaLaTeX

\usepackage{helvet}

\usetheme{Berlin}

\begin{document}

\begin{frame}
\textit{hello} \protect{\textit{hello}} hello 
\end{frame}

\end{document}

No matter what I do, the output is not italic. I have tried adding

\newcommand{\italnum}[1]{\begingroup\fontfamily{phv}\itshape#1\endgroup}

after the definition of the documentclass but this does not seem to work. Any ideas?

Answer 1

Don't use helvet with xelatex and lualatex, use e.g. the tex gyre heros font:

\documentclass[a4paper,11pt,fleqn]{beamer}
\usepackage[ngerman,english]{babel} % language listed last is default setting
\usepackage{fontspec} % load 'fontspec' when using XeLaTeX or LuaLaTeX

\setsansfont{TeX Gyre Heros}

\usetheme{Berlin}

\begin{document}

\begin{frame}
\textit{hello} \protect{\textit{hello}} hello
\end{frame}

\end{document}