What is the meaning of this String Theory Equation from CERN?

[Aaronaut]

I have recently visited CERN, and in the Globe they showed an equation from string theory.

My knowledge about it goes only as far as 'The elegant universe', so no mathematics, but i would say that the sketch beneath is about the string coupling constant.

Could anyone please explain the equation to me?

 

[arivero]

What level are you conversant at? Taylor's series, say?

The g in the subindex is "genus". A ball surface has genus zero, a donut surface has genus one, and so on, with the number of holes. The drawing is then a summation, the formula for each term given by the general rule above it.

The result of the summation would be, in this case, a "vacuum-to-vacuum" diagram, the probability for a string to come out of the vacuum, live for some time, and then disappear. It is the basis to build the same series for particular cases.