### Abstract

We consider the general hypermultiplet low-energy effective action (LEEA) that may appear in quantized, four-dimensional, N = 2 supersymmetric, gauge theories, e.g. in the Coulomb and Higgs branches. Our main purpose is a description of the exact LEEA of n magnetically charged hypermultiplets. The hypermultiplet LEEA is given by the N = 2 supersymmetric nonlinear sigma-model (NLSM) with a 4n-dimensional hyper-Kahler metric, subject to nonanomalous symmetries. Harmonic superspace (HSS) and the NLSM isometries are very useful to constrain the hyper-Kahler geometry of the LEEA. We use N = 2 supersymmetric projections of HSS superfields to N = 2 linear (tensor) O(2) and O(4) multiplets in N = 2 projective superspace (PSS) to deduce the explicit form of the LEEA in some particular cases. As the by-product, a simple new classification of all multimonopole moduli space metrics having su(2)R symmetry is proposed in terms of real quartic polynomials of 2n variables, modulo Sp(n) transformations. The 4d hypermultiplet LEEA for n = 2 can be encoded in terms of an elliptic curve.

Original language | English |
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Pages (from-to) | 2661-2713 |

Number of pages | 53 |

Journal | International Journal of Modern Physics A |

Volume | 15 |

Issue number | 17 |

DOIs | |

Publication status | Published - 10 Jul 2000 |

### ASJC Scopus subject areas

- Atomic and Molecular Physics, and Optics
- Nuclear and High Energy Physics
- Astronomy and Astrophysics