In theoretical physics, a twisted sector is a subspace of the full Hilbert space of closed string states in a particular theory over a (good) orbifold.
In the first quantized formalism of string theory (or maybe just plain old 2D conformal field theory) the target space is an orbifold M/G if the observables of the string are only defined modulo G. Consequently, the value of the field after one cycle around the closed string need only be the same as its original value modulo some G transformation.
i.e. there exists some such that
For each conjugacy class of G, we have a different superselection sector (wrt the worldsheet). The conjugacy class consisting of the identity gives rise to the untwisted sector and all the other conjugacy classes give rise to twisted sectors. It's easy to see that since the observables are only modulo G, two different g's which are conjugate to each other give rise to the same sector.
In the second quantized formalism, the different sectors give rise to different orbifold projections.
Famous quotes containing the word twisted:
“He took up his pen, which seemed to parch like a martyr in his hand. He began to write, nevertheless, addressing the nine-and-ninety lies of the moment he hoped with for a night of saloperie at the side of the twisted strumpet, Fiction, who lasciviously rolled her eyes at him, hiked up her skirt, and beckoned him on.”
—Alexander Theroux (b. 1940)