Spin dynamics of ${\mathrm{La}}_2$${\mathrm{CuO}}_4$ and the two-dimensional Heisenberg model

The spin-lattice relaxation rate 1/${\mathit{T}}_1$ and the spin-echo decay rate 1/${\mathit{T}}_{2\mathit{G}}$ for the two-dimensional Heisenberg model are calculated using quantum Monte Carlo and maximum-entropy analytic continuation. The results are compared with recent experiments on ${\mathrm{La}}_2$${\mathrm{CuO}}_4$, as well as predictions based on the nonlinear σ model.