What does Ept mean?

1. Sep 23, 2014

x BlueRobot

In an equation, there was an Ept (just those letters) embedded within that equation, does anyone know what it means? LaTeX code doesn't seem to be working either.

2. Sep 23, 2014

x BlueRobot

Don't worry, I think I've found the answer, the formatting within the paper made it look like a separate variable, but it's actually a product of two variables.