On the massless modes of the AdS3/CFT2 integrable systems

Understand

We make a proposal for incorporating massless modes into the spin-chain of the AdS3/CFT2 integrable system.

• We do this by considering the alpha to 0 limit of the alternating d(2,1;alpha)^2 spin-chain constructed in arXiv:1106.2558.
• In the process we encounter integrable spin-chains with non-irreducible representations at some of their sites.
• We investigate their properties and construct their R-matrices in terms of Yangians.