No abstract

We use the method of spectral networks to calculate BPS degeneracies in the Minahan-Nemeschansky E 7 theory, as representations of the E 7 flavor symmetry. Our results provide another example of a pattern noticed earlier in the Minahan-Nemeschansky E 6 theory: when the electromagnetic charge is n times a primitive charge, the BPS index is a positive integer multiple of (−1) n+1 n. We also calculate BPS degeneracies in the Minahan-Nemeschansky E 6 theory for larger charges than were previously computed. arXiv:1905.09879v1 [hep-th]

We study in detail the Schrödinger equation corresponding to the four dimensional SU(2) $$ \mathcal{N} $$ N = 2 SQCD theory with one flavour. We calculate the Voros symbols, or quantum periods, in four different ways: Borel summation of the WKB series, direct computation of Wronskians of exponentially decaying solutions, the TBA equations of Gaiotto-Moore-Neitzke/Gaiotto, and instanton counting. We make computations by all of these methods, finding good agreement. We also study the exact quantization condition for the spectrum, and we compute the Fredholm determinant of the inverse of the Schrödinger operator using the TS/ST correspondence and Zamolodchikov’s TBA, again finding good agreement. In addition, we explore two aspects of the relationship between singularities of the Borel transformed WKB series and BPS states: BPS states of the 4d theory are related to singularities in the Borel transformed WKB series for the quantum periods, and BPS states of a coupled 2d+4d system are related to singularities in the Borel transformed WKB series for local solutions of the Schrödinger equation.

We propose a connection between 3d-5d exponential networks and exact WKB for difference equations associated to five dimensional Seiberg-Witten curves, or equivalently, to quantum mirror curves to toric Calabi-Yau threefolds X: the singularities in the Borel planes of local solutions to such difference equations correspond to central charges of 3d-5d BPS KK-modes, and the central charges of 5d BPS KK-modes are related to the singularities in the Borel planes of the closed topological string free energy on X. It follows that there should be distinguished local solutions of the difference equation in each domain of the complement of the exponential network, and these solutions jump at the walls of the network. We verify this picture in detail in two simple examples of 3d-5d systems, corresponding to taking the toric Calabi-Yau X to be either C 3 or the resolved conifold. We provide the full list of local solutions in each sector of the Borel plane and in each domain of the complement of the exponential network, and find that local solutions in disconnected domains correspond to non-perturbative open topological string amplitudes on X with insertions of branes at different positions of the toric diagram. We also study the Borel summation of the closed refined topological string free energy on X and the corresponding non-perturbative effects.

It is known that some theories of class S are actually factorized into multiple decoupled nontrivial four-dimensional $$ \mathcal{N} $$ N = 2 theories. We propose a way of constructing examples of this phenomenon using the physics of half-BPS surface defects, and check that it works in one simple example: it correctly reproduces a known realization of two copies of $$ \mathcal{N} $$ N = 2 superconformal SU(2) QCD, describing this factorized theory as a class S theory of type A3 on a five-punctured sphere with a twist line. Separately, we also present explicit checks that the Coulomb branch of a putative factorized class S theory has the expected product structure, in two examples.