Spectral Functions of Strongly Interacting Isospin-$\frac{1}{2}$ Bosons in One Dimension

We study a system of one-dimensional (iso)spin-$\frac{1}{2}$ bosons in the regime of strong repulsive interactions. We argue that the low-energy spectrum of the system consists of acoustic density waves and the spin excitations described by an effective ferromagnetic spin chain with a small exchange constant $J$. We use this description to compute the dynamic spin structure factor and the spectral functions of the system.