Framed parabolic sheaves on a trinion

Abstract

We consider for structure groups $\mathrm{\text{SU}}(n)\subset \mathrm{\text{SL}}(n,ℂ)$ a densely defined toric structure on the moduli space of framed parabolic sheaves on a three-punctured sphere, which degenerates to an actual toric structure. In combination with previous degeneration results, these extend to similar moduli for arbitrary Riemann surfaces.