The large charge expansion

<!--HTML--><p>Over the last few years, it has become clear that working in sectors of large global charge leads to significant simplifications when studying strongly coupled CFTs, theories which are otherwise often inaccessible to analytic methods. It allows us in particular to calculate the CFT data as an expansion in inverse powers of the large charge.&nbsp;<br>In this talk, I will introduce the large-charge expansion via the simple example of the O(2) model and will then generalize it to the O(N) vector model which displays a richer structure due to its non-Abelian global symmetry group. Using large-N methods in conjunction with large charge gives us even more control over the dynamics and lets us study the system away from the conformal point.</p>