Quark Number Fractionalization in N=2 Supersymmetric $SU(2) \times U(1)^{N_f}$ Gauge Theories

It is shown that the physical ``quark number'' charges which appear in the central charge of the supersymmetry algebra of $N=2$ supersymmetric QCD can take irrational values and depend non trivially on the Higgs expectation value. This gives a physical interpretation of the constant shifts which the ``electric'' and ``magnetic'' variables $a_D$ and $a$ undergo when encircling a singularity, and show that duality in this model is truly an electric-magnetic-quark number duality...

Several dynamical aspects of the SU(2) Seiberg-Witten models with N_f quark hypermultiplets are explored. We first clarify the meaning of the number of the singularities of the space of vacua. CP invariance of the theories are then studied and periodicities of theories in \theta with and without bare quark masses are obtained ((4-N_f)\pi and \pi, respectively). CP noninvariance at a generic point of QMS manifests itself as the electric and quark-number charge fractionalizatio...

N=1^* gauge theories are believed to have fractional instanton contributions in the confining vacua. D3 brane probe computations in gravitation dual of large-N N=2^* gauge theories point to the absence of such contributions in the low energy gauge dynamics. We study fractional instantons in N=2 SU(2) Yang-Mills theory from the field theoretical perspective. We present new solutions to the Seiberg-Witten SU(2) monodromy problem with the same perturbative asymptotic, a massless...

Expressions for electric and magnetic charges of dyons, which become massless in the strong-coupling limit of the supersymmetric N=2 gauge theory with an arbitrary gauge group are presented. Transitions into different vacua of the N =1 gauge theory, when the N=2 supersymmetry is broken explicitly to the N =1 case, are discussed. The existence of a minimal set of light dyons, which are necessary to describe this transition, is established. The total number of these dyons equal...

We study the vacuum structure and dyon spectrum of N=2 supersymmetric gauge theory in four dimensions, with gauge group SU(2). The theory turns out to have remarkably rich and physical properties which can nonetheless be described precisely; exact formulas can be obtained, for instance, for electron and dyon masses and the metric on the moduli space of vacua. The description involves a version of Olive-Montonen electric-magnetic duality. The ``strongly coupled'' vacuum turns ...

A new discrete symmetry group, which governs low-energy properties of the supersymmetric N=2 gauge theory is found. Each element of this group S_r, r being the rank of the gauge group, represents a permutation of r electric charges available in the theory accompanied by a simultaneous permutation of r monopoles, provided the sets of charges and monopoles are chosen properly. Properties of the theory are strongly influenced by S_r; if the central charges (and masses) of r mono...

A first principles calculation of the quantum corrections to the electric charge of a dyon in an N=2 gauge theory with arbitrary gauge group is presented. These corrections arise from the fermion fields via the mechanism of fermion fractionalization. For a dyon whose magnetic charge is a non-simple co-root, the correction is a discontinuous function on the moduli space of vacua and the discontinuities occur precisely on co-dimension one curves on which the dyon decays. In thi...

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 dyon spectrum in $N=2$ Super Yang-Mills theory with gauge group $SU(2)$ coupled to $N_f$ matter multiplets in the fundamental representation. For magnetic charge one and two we determine the spectrum explicitly and show that it is in agreement with the duality predictions of Seiberg and Witten. We briefly discuss the extension to higher charge monopoles for the self-dual $N_f=4$ case and argue that the conjectured spectrum of dyons predicts the existence of certa...

We derive parts of the monopole and dyon spectra for N=2 super-Yang--Mills theories in four dimensions with gauge groups G of rank r>1 and matter multiplets. Special emphasis is put on G=SU(3) and those matter contents that yield perturbatively finite theories. There is no direct interpretation of the soliton spectra in terms of naive selfduality under strong--weak coupling and exchange of electric and magnetic charges. We argue that, in general, the standard procedure of fin...