How to get latex math into org headline

Question

Putting a math element into an org mode headline causes latex to complain. ie

* This contains $\prod_{k=1}^N$ math
Lorem ipsum

gives

Package hyperref Warning: Token not allowed in a PDF string (PDFDocEncoding):
(hyperref)                removing `math shift' on input line 29.


Package hyperref Warning: Token not allowed in a PDF string (PDFDocEncoding):
(hyperref)                removing `\prod@' on input line 29.


Package hyperref Warning: Token not allowed in a PDF string (PDFDocEncoding):
(hyperref)                removing `\slimits@' on input line 29.


Package hyperref Warning: Token not allowed in a PDF string (PDFDocEncoding):
(hyperref)                removing `subscript' on input line 29.


Package hyperref Warning: Token not allowed in a PDF string (PDFDocEncoding):
(hyperref)                removing `superscript' on input line 29.

Answer 1

After posting I found a reference in the Org mode mailing list showing how to get round this issue.

Following: the first headline shows org developer Nicolas Goaziou's solution. The second shows how to tighten it a bit with an org mode macro mt which takes math ($$ implied) in arg-1 and equivalent ASCII in arg-2 to keep hyperref happy.

#+MACRO: mt @@latex:\texorpdfstring{$ $1 $}{$2}@@
# mt = math-text
* This contains @@latex:\texorpdfstring{$\prod_{k=1}^N$}{product 1toN}@@ math
Lorem ipsum
* This is better {{{mt(\prod_{k=3}^N,product 1toN)}}} math
Dolor sit amet.