Weak Coupling Chambers in N=2 BPS Quiver Theory

The BPS spectrum of certain N=2 supersymmetric field theories can be determined algebraically by studying the representation theory of BPS quivers. We introduce methods based on BPS quivers to study line defects. The presence of a line defect opens up a new BPS sector: framed BPS states can be bound to the defect. The defect can be geometrically described in terms of laminations on a curve. To a lamination we associate certain elements of the Leavitt path algebra of the BPS q...

The BPS spectrum of many 4d N=2 theories may be seen as the (categorical) Galois cover of the BPS spectrum of a different 4d N=2 model. The Galois group G acts as a physical symmetry of the covering N=2 model. The simplest instance is SU(2) SQCD with N_f=2 quarks, whose BPS spectrum is a Z_2-cover of the BPS spectrum of pure SYM. More generally, N=2 SYM with simply--laced gauge group admits Z_k-covers for all k; e.g. the Z_2-cover of SO(8) SYM is SO(8) SYM coupled to two copi...

Extending results of arXiv:1112.3984, we show that all rank 1 N=2 SCFT's in the sequence H_1, H_2, D_4 E_6, E_7, E_8 have canonical finite BPS chambers containing precisely 2 h(F)=12(Delta-1) hypermultiplets. The BPS spectrum of the canonical BPS chambers saturates the conformal central charge c, and satisfies some intriguing numerology.

We explicitly determine the global structure of the $SL(2,Z)$ bundle over the Coulomb branch of the moduli space of asymptotically free $N=2$ supersymmetric Yang-Mills theories with gauge group $SU(2)$ when massless hypermultiplets are present. For each relevant number of flavours, we show that there is a curve of marginal stability on the Coulomb branch, diffeomorphic to a circle, across which the BPS spectrum is discontinuous. We determine rigorously and completely the BPS ...

Actual calculations of monopole and dyon spectra have previously been performed in N=4 SYM and in N=2 SYM with gauge group SU(2), and are in total agreement with duality conjectures for the finite theories. These calculations are extended to N=2 SYM with higher rank gauge groups, and it turns out that the SU(2) model with four fundamental hypermultiplet is an exception in that its soliton spectrum supports duality. This may be an indication that the other perturbatively finit...

We study the stability and spectrum of BPS states in ${\cal N}=2$ supergravity. We find evidence, and prove for a large class of cases, that BPS stability exhibits a certain filtration which is partially independent of the value of the gauge couplings. Specifically, for any perturbative value of any gauge coupling $g \ll 1$, a BPS state can only decay to some constituents if those constituents do not become infinitely heavier than it in the vanishing coupling limit $g \righta...

These notes are based on work done in collaboration with Frank Ferrari. We show how to determine the spectra of stable BPS states in $N=2$ supersymmetric $SU(2)$ Yang-Mills theories that are asymptotically free, i.e. without and with $N_f=1,2,3$ quark hypermultiplets. In all cases: $\bullet$ There is a curve of marginal stability diffeomorphic to a circle and going through all (finite) singular points of moduli space. $\bullet$ The BPS spectra are discontinuous across these c...

BPS states in supersymmetric theories can admit additional algebro-geometric structures in their spectra, described as quiver Yangian algebras. Equivariant fixed points on the quiver variety are interpreted as vectors populating a representation module, and matrix elements for the generators are then defined as Duistermaat-Heckman integrals in the vicinity of these points. The well-known wall-crossing phenomena are that the fixed point spectrum establishes a dependence on the...

We demonstrate that $\mathcal{N}=2$ supersymmetric non-Abelian gauge theories have towers of BPS particles obeying a Regge relation, $J \sim m^{2},$ between their angular momenta, $J,$ and their masses, $m$. For $SU(N)$ Yang-Mills theories, we estimate the slope of these Regge trajectories using a non-relativistic quiver quantum mechanics model. Along the way, we also prove various structure theorems for the quiver moduli spaces that appear in the calculation.

BPS spectrum with finite number of states are found for higher rank four dimensional N=2 theory engineered from six dimensional A_{N-1} (2,0) theory on a Riemann surface with various kinds of defects. The wall crossing formula is interpreted as the quantum dilogarithm identity. Various methods including quiver representation theory, maximal green mutation, and cluster algebra are used extensively. The spectral generator and its refined version for the higher rank theory are w...