 First massive GSO-projected Ramond states

At R level one, the families are ${\alpha }_{-1}^i|s⟩$ and $d_{-1}^i|s^{\prime }⟩$, each of dimension $8\cdot 8$. The zero-mode spinors have opposite chirality because the one fermionic oscillator reverses the oscillator contribution to the GSO projection. The resulting 128 states form a gamma-traceless Spin(9) vector-spinor, of dimension $9\cdot 16-16$.