## Abstract

We consider N = 2 SUSY QCD with gauge group SU(2) and N_{f} flavours of matter with non-zero mass. Using the method of the instanton-induced effective vertex we calculate higher derivative corrections to the Seiberg-Witten result in the momentum expansion of the low energy effective Lagrangian in various regions of the modular space. Then we focus on a certain higher derivative operator on the Higgs branch. We show that the singular behaviour of this operator comes from values of the mass of matter at which the charge singularity on the Coulomb branch collides with the monopole or dyon singularity. Given the behaviour of this operator at weak coupling coming from instantons as well as its behaviour near the points of colliding singularities we find the exact solution for this operator.

Original language | English (US) |
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Pages (from-to) | 79-102 |

Number of pages | 24 |

Journal | Nuclear Physics B |

Volume | 512 |

Issue number | 1-2 |

DOIs | |

State | Published - Feb 16 1998 |

### Bibliographical note

Funding Information:The author is grateful to M. Grisaru, T. Eguchi, I. Sachs, M. Shifinan, A. Schwimmer and A. Vainshtein for helpful discussions and to the organizers of the program "Non-perturbative aspects of Quantum Field Theory" at the Isaac Newton Institute, Cambridge, where this work was finished, for hospitality. This work is supported by the Russian Foundation for Fundamental Studies under Grant No. 96-02-18030.

## Keywords

- Instanton
- Particle physics
- Seiberg-Witten theory
- Supersymmetry