Find the Value of T3: D3 Brane Tension

[deadringer]

I'm doing a theory project on Cosmological inflation, and I've been given an equation which involves T3 which is "the effective tension of the D3 brane". I think that this is probably a numerical constant, but it's not clear from the context. If it is a constant, how could I find out the numerical value?

 

[Chronos]

T3 is not a number, it's a derivative.