To insert an equation or symbol in an axis title of an Excel scatter plot, you can use the "Insert Symbol" feature. Here are the steps to insert the accented lower case Greek symbol for shear rate "gamma dot" :

1. Click on the axis title to select it.
2. In the "Insert" tab, click on "Symbol" in the "Symbols" group.
3. In the "Symbol" dialog box, select "Greek and Coptic" in the "Subset" drop-down list.
4. Scroll down to find the "gamma dot" symbol (it should be near the bottom of the list).
5. Click on the "gamma dot" symbol to select it.
6. Click on the "Insert" button to insert the symbol into the axis title.
7. Click on the "Close" button to close the "Symbol" dialog box.

The accented lower case Greek symbol for shear rate "gamma dot" should now be inserted into the axis title of your Excel scatter plot.