All Questions
2
questions
1
vote
1
answer
123
views
Why is the gauge group of pseudo-fermion mapping referred to as $\mathrm{SU}(2)$ and not $\mathrm U(2)$?
The representation of spin $\frac{1}{2}$ operators $\hat{S}^{a}$ by pseudo-fermions (also called Abrikosov fermions) is defined by the mapping
$$
\hat{S}^{a} = \frac{1}{2} \text{Tr}\big[ \hat{\psi}^{\...
- 11
0
votes
1
answer
93
views
$\mathbb{Z}_2$ gauge theory and disorder
I am confused about basics of $\mathbb{Z}_2$ (and likely other) gauge theories and plain disorder. Let
$$H=H_F + h\,H_{EM}$$
$$H_F = -t\sum_l (c^\dagger_l \sigma^z_{l,l+1} c_{l+1} + h.c.)$$
be (the '...
- 101