I experienced a similar problem with superscripts. Searching for a solution I encountered your question.
Problem Description: Just typeset
The alignment is wrong.
Further search, which might contribute to a solution, revealed that:
Q#1 It is not a
xelatex bug, because typesetting with
eulervm as a math font and the
mathspec package does not lead to this behavior.
It is also not an error of opentype font metrics, because the above formulae appear correctly in Word 2010 using Cambria Math (this is embarrassing).
Therefore, I am led to believe that there is something rotten in the code of the
Q#2: Reading the documentation of the
unicode-math package, I didn't find any way of correcting this behavior except for modifying the source code, which I don't know how to do.
I think that this should be filed as an example of an unwanted behavior (or bug) to the maintainer of the
unicode-math package, in order to be corrected in future versions.
lualatex cannot be a general solution, because (at least in my case) I need
polyglossia's features, as my text involves English, Greek and some Russian text and
polyglossia has its problems with
lualatex (or the other way around?).
You can do the following:
\vphantomcommand makes vertical space the same height its argument. Depending on how often you need this or how predictable it is, you might be able to make a macro to add the