First massive level of a chiral RNS sector
= First massive level of a chiral RNS sector
{title2=$N_{\rm NS}=3/2,\quad N_R=1,\quad M^2=4/\alpha'$}
After the <GSO projection>, the first positive shifted level is one: $N_{\rm NS}=3/2$ and $N_R=1$. In a closed-string mass convention it corresponds to $M^2=4/\alpha'$. The transverse oscillator basis has 128 NS states and 128 R states. They form the bosonic and fermionic pieces of a massive <supersymmetry> multiplet.