%0 Journal Article %T Linear perturbations of quaternionic metrics %+ Laboratoire de Physique Théorique et Astroparticules (LPTA) %+ Laboratoire de Physique Théorique et Hautes Energies (LPTHE) %+ Institut de Physique Théorique - UMR CNRS 3681 (IPHT) %+ Institute for Theoretical Physics [Utrecht] %A Alexandrov, Sergey %A Pioline, Boris %A Saueressig, Frank %A Vandoren, Stefan %Z MRTN-CT-2004-005104 %Z 55 pages, 1 figure, uses JHEP3.cls %< avec comité de lecture %Z 08-054 %@ 0010-3616 %J Communications in Mathematical Physics %I Springer Verlag %V 296 %N 2 %P 353-403 %8 2010 %D 2010 %Z 0810.1675 %R 10.1007/s00220-010-1022-y %K High Energy Physics %K Theory %K Mathematics %K Differential Geometry %Z Physics [physics]/High Energy Physics - Theory [hep-th]Journal articles %X We extend the twistor methods developed in our earlier work on linear deformations of hyperkahler manifolds [arXiv:0806.4620] to the case of quaternionic-Kahler manifolds. Via Swann's construction, deformations of a 4d-dimensional quaternionic-Kahler manifold $M$ are in one-to-one correspondence with deformations of its $4d+4$-dimensional hyperkahler cone $S$. The latter can be encoded in variations of the complex symplectomorphisms which relate different locally flat patches of the twistor space $Z_S$, with a suitable homogeneity condition that ensures that the hyperkahler cone property is preserved. Equivalently, we show that the deformations of $M$ can be encoded in variations of the complex contact transformations which relate different locally flat patches of the twistor space $Z_M$ of $M$, by-passing the Swann bundle and its twistor space. We specialize these general results to the case of quaternionic-Kahler metrics with $d+1$ commuting isometries, obtainable by the Legendre transform method, and linear deformations thereof. We illustrate our methods for the hypermultiplet moduli space in string theory compactifications at tree- and one-loop level. %G English %L hal-00328291 %U https://hal.science/hal-00328291 %~ IN2P3 %~ CEA %~ UNIV-PARIS7 %~ UPMC %~ LPTA %~ CNRS %~ LPTHE %~ UNIV-MONTP2 %~ DSM-IPHT %~ UPMC_POLE_2 %~ UNIV-MONTPELLIER %~ CEA-DRF %~ SORBONNE-UNIVERSITE %~ SU-SCIENCES %~ UNIV-PARIS %~ SU-TI %~ ANR %~ GS-MATHEMATIQUES %~ GS-PHYSIQUE %~ ALLIANCE-SU %~ UM1-UM2