# Are string theories gauge theories?

+ 1 like - 0 dislike
18 views

The wikipedia page for String Theory lists SO(32) and E8×E8 as group symmetries of some of the string theory types, and the page on E8 says:

E8×E8 is the gauge group of one of the two types of heterotic string

Am I to infer from this that these string theories are "gauge theories" (I guess "string gauge theories" rather than "QFT gauge theories"), or am I missing something? I certainly can't find any literature that ever calls String Theory a "gauge theory".

This post imported from StackExchange Physics at 2015-04-11 10:50 (UTC), posted by SE-user user1247
Define gauge theory (I think it's subjective) and we'll see then.

This post imported from StackExchange Physics at 2015-04-11 10:50 (UTC), posted by SE-user Chris Gerig
@Chris Gerig, well, I would say it would mean that adding a requirement of local invariance under some continuous symmetry group implies the necessary existence of some compensating field or stringy-feature that gives rise to dynamics....

This post imported from StackExchange Physics at 2015-04-11 10:50 (UTC), posted by SE-user user1247

+ 5 like - 0 dislike

In almost of its $d=4$ vacua, string theory contains Yang-Mills degrees of freedom or light spin-one particles so that in the form of the string field theory, it may be rewritten as a field theory with a gauge group, a generalized Yang-Mills theory with infinitely many fields charged under the gauge group. The gauge symmetry is exact in this formulation because it's what removes the unphysical polarizations of the gauge fields.

However, string theory is not a local quantum field theory and the gauge symmetry isn't a fundamental assumption in string theory – it and the corresponding polarizations of the gauge bosons are derived from something more fundamental, from the maths of string theory (e.g. from conditions of the world sheet conformal field theory if we deal with the string theory perturbatively). General relativity also follows from string theory (much like Yang-Mills theory, the diffeomorphism invariance is exact whenever we rewrite string theory in a form that includes $g_{\mu\nu}$ as the degrees of freedom) but it's a derived result, an infinitesimal glimpse of the superior power of string theory.

It's hard to answer your question because the phrases you use are ill-defined – in particular, you don't say whether a gauge theory has to be a local quantum field theory in spacetime (string theory is not one). But I believe that the paragraphs above answer all meaningful questions that one could get by clarifying yours.

This post imported from StackExchange Physics at 2015-04-11 10:50 (UTC), posted by SE-user Luboš Motl
answered Mar 26, 2013 by (10,258 points)

 Please use answers only to (at least partly) answer questions. To comment, discuss, or ask for clarification, leave a comment instead. To mask links under text, please type your text, highlight it, and click the "link" button. You can then enter your link URL. Please consult the FAQ for as to how to format your post. This is the answer box; if you want to write a comment instead, please use the 'add comment' button. Live preview (may slow down editor)   Preview Your name to display (optional): Email me at this address if my answer is selected or commented on: Privacy: Your email address will only be used for sending these notifications. Anti-spam verification: If you are a human please identify the position of the character covered by the symbol $\varnothing$ in the following word:p$\hbar$ysic$\varnothing$OverflowThen drag the red bullet below over the corresponding character of our banner. When you drop it there, the bullet changes to green (on slow internet connections after a few seconds). To avoid this verification in future, please log in or register.