Take the 2-minute tour ×
Physics Stack Exchange is a question and answer site for active researchers, academics and students of physics. It's 100% free.

In solid state physics emergent particles are very common.

  1. How one determines if they are gap-less excitations?

  2. Do the defects in spin ice called magnetic monopoles have mass?

  3. What is the mass of emergent particles in the fractional quantum hall effect (FQHE)?

I am not looking for a deep theory, just the general picture.

share|improve this question

1 Answer 1

up vote 1 down vote accepted
  1. I do not think there is anything one can say in full generality about determining whether "emergent" particles. Goldstone's theorem guarantees gapless excitations in some cases, but really you just gotta talk about the specfic problems.
  2. The spin-ice monopoles (which must be produced in pairs) should have a mass gap since introducing a new pair requires you to violate the spin-ice rules at a new location which has a finite energy cost. See Equation (2) of the original paper by Castelnovo, Moessner and Sondhi.
  3. The excitation spectrum of FQHE has a thirty year history of experimental and theoretical study of an enormous number of distinct states, so I don't know that a short answer can be given.
share|improve this answer

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.