Re: What is an instanton? How is it related to particle decay?

Hi Yevgeniy,

Sorry for taking so long to respond; as an experimentalist, instantons (previously also called pseudoparticles) are pretty far from my day-to-day work.

In spite of the suggestive name, instantons are not a kind of particle. In particle physics, they are part of an approach for solving quantum field theory problems using classical equations of motion in Euclidean space-time.

Basically, the instanton approach first involves transforming a problem from four- dimensional Minkowski spacetime (where the space and time axes are all real) to Euclidean spacetime (where the time axis is imaginary).

After this transformation, it is often possible to find one or many classical solutions to the equations of motion that can be solved in a straightforward way. These classical solutions are called instantons.

Once these classical solutions have been solved, the problem is transformed back to Minkowski spacetime to see the physical results.

So instantons aren't themselves responsible for particle decays, but they can be used to help us understand and calculate them.