Search for NS 3-form Flux Induced Vacua for the Critical Non-Abelian Vortex String

Abstract: It has been demonstrated that the non-Abelian solitonic vortex string in four-dimensional (4D) $\mathcal{N}=2$ supersymmetric QCD (SQCD) with gauge group U(2) and $N_f=4$ quark hypermultiplets behaves as a critical superstring. This string propagates in a ten-dimensional space comprising the flat 4D space and an internal Calabi-Yau noncompact threefold, specifically, the conifold. The lowest state of this string is a massless BPS baryon associated with the deformation of the conifold's complex structure modulus, $b$. Previous studies considered deformations of the 10-dimensional background by a nonzero Neveu-Schwarz (NS) 3-form flux, which was interpreted as selecting specific quark masses in 4D SQCD. These deformations and the corresponding back reaction on the metric were analyzed at the leading order at small 3-form flux. In this paper, we first derive the exact potential for the conifold complex structure modulus $b$ generated by the 3-form flux assuming a fixed conifold background. Then we include the back reaction effects and solve the corresponding gravity equations of motion. We show that the resulting potential gives a runaway vacuum. At this runaway vacuum the conifold undergoes degeneration.