New Superparticle Models Outside the HLS Supersymmetry Scheme

We consider the superparticle models invariant under the supersymmetries with tensorial central charges, which were not included in D = 4 Haag-LopuszanskiSohnius (HLS) supersymmetry scheme. We present firstly a generalization of D = 4 Ferber-Shirafuji (FS) model with fundamental bosonic spinors and tensorial central charge coordinates. The model contains four fermionic coordinates and possesses three κ-symmetries thus providing the BPS configuration preserving 3/4 of the target space supersymmetries. We show that the physical degrees of freedom (8 real bosonic and 1 real Grassmann variable) of our model can be described by OSp(8|1) supertwistor. Then we propose a higher dimensional generalization of our model with one real fundamental bosonic spinor. D = 10 model describes massless superparticle with composite tensorial central charges and in D = 11 we obtain 0-superbrane model with nonvanishing mass which is generated dynamically. The introduction of D = 11 Lorentz harmonics provides the possibility to construct massless D = 11 superparticle model can be formulated in a way preserving 1/2, 17/32, 18/32, . . ., 31/32 supersymmetries. In a special case we obtain the twistor-like formulation of the usual massless D = 11 superparticle proposed recently by Bergshoeff and Townsend. ∗ To be published in the Proceedings of 12-th Max Born Symposium: Theoretical Physics Fin de Siecle, held 24-27.09.1998 in Wroclaw (Poland), ed. by A. Borowiec, B. Jancewicz, W. Karwowski and W. Cegla, Springer Verlag. † Lise Meitner Fellow. On leave of absence from Institute for Theoretical Physics, NSC Kharkov Institute of Physics and Technology, 310108 Kharkov, Ukraine ‡ On leave of absence from Institute for Theoretical Physics, University of Wroclaw, 50-204 Wroclaw, Poland. Supported in part by KBN grant 2P03B13012