45 research outputs found

    Contra el relativisme

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    Einstein: l'home i el geni

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    Ciència i filosofia

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    Spacetime scale-invariant super-p-brane actions on enlarged superspaces and the geometry of kappa-symmetry

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    We use the additional variables of suitably enlarged superspaces to write new actions for extended objects, with kappa-symmetry, in such a way that the tension emerges from them as an integration constant. Our actions correspond to the spacetime scale-invariant ones previously considered by Bergshoeff et al. once the worldvolume forms introduced there are reinterpreted in terms of fields associated with the coordinates of the enlarged superspaces. It is shown that the kappa-symmetry of the new actions is given by a certain type of right local transformations of the extended superspace groups. Further, we also show that the enlarged superspaces that allow for strictly invariant Wess-Zumino terms also lead to strict kappa-invariance i.e., the Lagrangian itself (not only the action) is both supersymmetry- and kappa-invariant.Comment: 23 pages, no figures. A clarifying comment and a reference adde

    Contractions of Filippov algebras

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    We introduce in this paper the contractions Gc\mathfrak{G}_c of nn-Lie (or Filippov) algebras G\mathfrak{G} and show that they have a semidirect structure as their n=2n=2 Lie algebra counterparts. As an example, we compute the non-trivial contractions of the simple An+1A_{n+1} Filippov algebras. By using the \.In\"on\"u-Wigner and the generalized Weimar-Woods contractions of ordinary Lie algebras, we compare (in the G=An+1\mathfrak{G}=A_{n+1} simple case) the Lie algebras LieGc\,\mathfrak{G}_c (the Lie algebra of inner endomorphisms of Gc\mathfrak{G}_c) with certain contractions (LieG)IW(\mathrm{Lie}\,\mathfrak{G})_{IW} and (LieG)WW(\mathrm{Lie}\,\mathfrak{G})_{W-W} of the Lie algebra LieG\,\mathfrak{G} associated with G\mathfrak{G}.Comment: plain latex, 36 pages. A few misprints corrected. This v3 is actually v2 (v1 had been replaced by itself by error). To appear in J. Math. Phy

    Generalized curvature and the equations of D=11 supergravity

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    It is known that, for zero fermionic sector, the bosonic equations of Cremmer-Julia-Scherk eleven-dimensional supergravity can be collected in a compact expression which is a condition on the curvature of the generalized connection. Here we peresent the equation which collects all the bosonic equations of D=11 supergravity when the gravitino is nonvanishing.Comment: 8 pages, plain latex. A few numerical factors corrected. To appear in Phys. Lett.

    On BPS preons, generalized holonomies and D=11 supergravities

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    We develop the BPS preon conjecture to analyze the supersymmetric solutions of D=11 supergravity. By relating the notions of Killing spinors and BPS preons, we develop a moving G-frame method (G=GL(32,R), SL(32,R) or Sp(32,R)) to analyze their associated generalized holonomies. As a first application we derive here the equations determining the generalized holonomies of k/32 supersymmetric solutions and, in particular, those solving the necessary conditions for the existence of BPS preonic (31/32) solutions of the standard D=11 supergravity. We also show that there exist elementary preonic solutions, i.e. solutions preserving 31 out of 32 supersymmetries in a Chern--Simons type supergravity. We present as well a family of worldvolume actions describing the motion of pointlike and extended BPS preons in the background of a D'Auria-Fre type OSp(1|32)-related supergravity model. We discuss the possible implications for M-theory.Comment: 11 pages, RevTeX Typos corrected, a short note and references adde

    On the absence of BPS preonic solutions in IIA and IIB supergravities

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    We consider the present absence of 31 out of 32 supersymmetric solutions in supergravity i.e., of solutions describing BPS preons. A recent result indicates that (bosonic) BPS preonic solutions do not exist in type IIB supergravity. We reconsider this analysis by using the G-frame method, extend it to the IIA supergravity case, and show that there are no (bosonic) preonic solutions for type IIA either. For the classical D=11 supergravity no conclusion can be drawn yet, although the negative IIA results permit establishing the conditions that preonic solutions would have to satisfy. For supergravities with `stringy' corrections, the existence of BPS preonic solutions remains fully open.Comment: plain latex, 12 pages Minor misprints corrected. Published in JHEP 09 (2006) 00

    BPS states in M-theory and twistorial constituents

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    We provide a complete algebraic description of BPS states in M-theory in terms of primary constituents that we call BPS preons. We argue that any BPS state preserving kk of the 32 supersymmetries is a composite of (32-k) BPS preons. In particular, the BPS states corresponding to the basic M2 and M5 branes are composed of 16 BPS preons. By extending the M-algebra to a generalized D=11 conformal superalgebra osp(164)osp(1|64) we relate the BPS preons with its fundamental representation, the D=11 supertwistors.Comment: 4 pages. Refs. updated, two cosmetic changes, to appear in PR
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