Physics Stack Exchange is a question and answer site for active researchers, academics and students of physics. It's 100% free.

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

In Xiao-Gang Wen's review of topological order , he states in footnote 52 that string-nets are so far unable to produce the chiral coupling between the SU(2) gauge boson and the fermions. Is it known how this chiral coupling can be expressed in lattice gauge theory, and the remaining question is one of emergence; or is it the case that its expression in lattice gauge theory is unknown, analogous to the chiral fermion question which took many years to solve?

share|cite|improve this question
My impression is that we have the same problem in lattice gauge theory, which is so far unable to produce the chiral coupling between the SU(2) gauge boson and the fermions. I understand that there is some progress, but I do not know if the problem is fully solved. – Xiao-Gang Wen Jan 5 '13 at 22:09
Thanks for the reply! As you say, it does seem not fully solved yet. Kaplan's review says "there is currently no practical way to regulate general nonabelian chiral gauge theories on the lattice." Poppitz and Shang say "we do not yet have a method of approximating an arbitrary chiral gauge theory by latticizing and then simulating it on a computer|even in principle." – Andrew Tan Jan 6 '13 at 3:51

The chiral-fermion/chiral-gauge-theory problem is solved: any anomaly-free chiral gauge theories can be put on lattice by simply turning on a proper interaction. See my new papers and

As a result, the string-net theory can also produce the coupling between the SU(2) gauge boson and the chiral fermions.

share|cite|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.