black hole spacetimes | vanishing angular momentum | positive angular momentum |
---|---|---|
vanishing charge | Schwarzschild spacetime | Kerr spacetime |
positive charge | Reissner-Nordstrom spacetime | Kerr-Newman spacetime |
superalgebra and (synthetic ) supergeometry
The equations of motion of supergravity typically imply – or are even equivalent to (Candiello-Lechner 93, Howe 97), that the super-torsion of the super-vielbein fields vanishes. At least in some cases these supergravity torsion constraints may naturally be understood as saying that supergravity solutions are (higher) super-Cartan geometry modeled on extended super Minkowski spacetime with its canonical torsion of a G-structure, due to the fact that the left invariant 1-forms on super-Minkowski space are not closed.
The torsion constraint is naturally understood by regarding supergravity as Cartan geometry for the inclusion of the orthogonal group into a super Poincare group and by noticing that the corresponding local model space, which is super-Minkowski spacetime $\mathbb{R}^{d|N}$, canonically has non-vanishing torsion.
Let $(x^a, \theta^\alpha)$ be the canonical coordinates on the supermanifold $\mathbb{R}^{d|N}$ underlying the super translation group. Then the left-invariant 1-forms are
$\psi^\alpha = d \theta^\alpha$.
$e^a = d x^a + \frac{i}{2} \overline{\theta} \Gamma^a d \theta$.
Here the extra summand in the equation for $e^a$ (necessary to make it left-invariant) causes it to be non-closed:
Taking the spin connection $(\omega^a{}_b)$ on $\mathbb{R}^{d|N}$ to vanish, as usual, this means that there is non-vanishing torsion:
Depending on perspective one might say that it is the supertorsion that vanishes (see at super-Minkowski spacetime and at D'Auria-Fre formulation of supergravity for this perspective), or, alternatively, that one is dealing with Cartan geometry/G-structure whose local model space carries non-vanishing torsion, see below.
Notice that the torison-full but left-invariant forms are of course obtained from the torsion-free but non-left-invartiant forms by a $GL(\mathbb{R}^{d|N})$-valued function:
This shows that regarding
as a super-vielbein is consistent: this is indeed a homotopy in
but not the tautological one given by
where the left triangle is that which exhibits the canonical trivialization of the frame bundle of $\mathbb{R}^{d|N}$.
Given a subgroup $G\hookrightarrow GL(V)$ of the general linear group of a linear model space $V$ (e.g. super-Minkowski spacetime $\mathbb{R}^{d|N}$), then a G-structure is first-order integrable if on the first-order infinitesimal neighbourhoods of any point it is equal to the canonical (trivial) $G$-structure on $V$. Ordinarily the standard torsion on $V$ vanishs, and if so then so does that of any first-order integrable $G$-structire, which is the reason why for these the torsion of a G-structure vanishes.
But in the situation of $V$ being super-Minkowski spacetime as above, the torsion of the local model space does not vanish, and so accordingly neither does that of a first-order integrable $G$-structure in this case.
This perspective on the torsion constraints in supergravity is adopted in (Lott 01), see there around (38) of the original article or section 4 of the review on the arXiv.
The supergravity equations of motion typically imply the torsion constraints. See at super p-brane – On curved spacetimes for more.
With enough supersymmetry, the torsion constraints (always together with the Bianchi identities on the superfields, see at D'Auria-Fre formulation of supergravity) may even become equivalent to the supergravity equations of motion. This is so for 11-dimensional supergravity (Candiello-Lechner 93, Howe 97, see Cederwall-Gran-Nilsson-Tsimpis 04, section 2.4) and maybe its maximally supersymmetric KK-compactifications. See at Examples – 11d SuGra.
A close analogy between CR geometry and supergravity superspacetimes (as both being torsion-ful integrable G-structures) is pointed out in (Lott 01 exposition (4.2)).
In accord with the above, typically the equations of motion of a supergravity theory constrain the spinorial part of the torsion to have components $(\Gamma^a)_{\alpha \beta}$.
The torsion constraint for 11-dimensional supergravity is discussed for instance in (Bergshoeff-Sezgin-Townsend 87, equation (14)).
Here something special happens:
The articles (Candiello-Lechner 93 (5.6), Howe 97, see Cederwall-Gran-Nilsson-Tsimpis 04, section 2.4) show that imposing the torsion constraint (on some chart) $\mathbf{d} E^a + \omega^{a}{}_b \wedge E^b - \bar \psi \Gamma^a \psi = 0$ as well as $(\mathbf{d} \Psi +\tfrac{1}{4}\omega^{a b} \Gamma_{a b}\Psi)_{\theta \theta} = 0$ implies the equations of motion of 11d supergravity.
Moreover, setting $\mathbf{d} \Psi +\tfrac{1}{4}\omega^{a b} \Gamma_{a b}\Psi = 0$ generally (not just the component proportional to the wedge product of two fermionic 1-forms, hence requiring the full supertorsion tensor to be that of super-Minkowski spacetime)) then (Candiello-Lechner 93, (5.8) with (6.5)) this in addition puts the field strength of the supergravity C-field to 0. Hence this implies solutions to the ordinary vacuum Einstein equations in 11d. Such solutions are considered notably in the context of M-theory on G2-manifolds (e.g. Acharya 02, p. 9). See also at M-theory on G2-manifolds – Details – Vacuum solution and torsion constraints.
For heterotic supergravity in 10d the equations of motion are equivalent to the condition that
the super-torsion of the bosonic part $\{e^a\}$ of the super vielbein is a bosonic form
the super-torsion of the odd part $\psi^\alpha$ of the super vielbein is of the form
for
proportional to the bispinor formed by tracing the square of the gaugino field $\chi$
the curvature 2-form of the gauge field has vanishing bispinorial component:
(this is the 10d super Yang-Mills theory sector)
This is due to (Witten 86 (5)+(27)), see also (Atick-Dhar-Ratra 86 (4.1)). These authors do not state explicitly that $\phi^{\alpha \beta} \propto tr(\lambda^\alpha \lambda^\beta) - tr (T T)$. (Among authors using a similar but different parameterization this statement is made explicit in Candiello-Lechner 93 (2.5) with (2.29)). But this follows by taking the differential of the bispinorial part of the 3-form field (which is the cocycle term for the heterotic Green-Schwarz superstring)
where we used the relation (Witten 86 (8)) (recalled for instance in Bonora-Bregola-Lechner-Pasti-Tonin 87 (2.28), Lechner-Tonin 08 (2.13)).
According to (Bonora-Bregola-Lechner-Pasti-Tonin 90) in fact all these constraints follow from just $T^a_{\alpha \beta} \propto \Gamma^a_{\alpha \beta}$.
The formulation of supergravity equations of motion in terms of constraints on the torsion tensor goes back to
A mathematical formulation in terms of torsion-full first-order integrable G-structures on supermanifolds (for low dimensional supergravity theories) is given in
which is followed up in
Discussion of torsion constrains for 11-dimensional supergravity from the point of view of consistency of the membrane Green-Schwarz action functional is in
The claim that this torsion constraint in 11-dimensional supergravity is already equivalent to all of the equations of motion is due to
A. Candiello, K. Lechner, Duality in Supergravity Theories, Nucl.Phys. B412 (1994) 479-501 (arXiv:hep-th/9309143)
Paul Howe, Weyl Superspace, Physics Letters B, Volume 415, Issue 2, 11 December 1997, Pages 149–155 (arXiv:hep-th/9707184)
concisely reviewed in
For commentary see also (Nilsson 00, section 2) and
also
Discussion of possible deformations of the torsion constraint (M-theory corrections) includes
Martin Cederwall, Ulf Gran, Mikkel Nielsen, Bengt Nilsson, Generalised 11-dimensional supergravity, in A. Semikhatov, M. Vasiliev and V. Zaikin (eds.) Proceedings of “Quantization, Gauge Theory & Strings”, Moscow 2000 (arXiv:hep-th/0010042)
Paul Howe, Dimitrios Tsimpis, On higher-order corrections in M theory, JHEP 0309 (2003) 038 (arXiv:hep-th/0305129)
Discussion of torsion constraints for heterotic supergravity goes back to (Nilsson 81) and includes
Paul Howe, A. Umerski, On superspace supergravity in ten dimensions, Phys. Lett. B 177 (1986) 163.
Joseph Atick, Avinash Dhar, and Bharat Ratra, Superspace formulation of ten-dimensional N=1 supergravity coupled to N=1 super Yang-Mills theory, Phys. Rev. D 33, 2824, 1986 (doi.org/10.1103/PhysRevD.33.2824)
Edward Witten, Twistor-like transform in ten dimensions, Nuclear Physics B Volume 266, Issue 2, 17 March 1986
Loriano Bonora, M. Bregola; Kurt Lechner, Paolo Pasti, Mario Tonin, Anomaly-free supergravity and super-Yang-Mills theories in ten dimensions, Nuclear Physics B
Volume 296, Issue 4, 25 January 1988 (doi:10.1016/0550-3213(88)90402-6)
Loriano Bonora, M. Bregola; Kurt Lechner, Paolo Pasti, Mario Tonin, A discussion of the constraints in $N=1$ SUGRA-SYM in 10-D, International Journal of Modern Physics A, February 1990, Vol. 05, No. 03 : pp. 461-477 (doi:10.1142/S0217751X90000222)
Paul Howe, Heterotic supergeometry revisited (arXiv:0805.2893)
Bengt Nilsson, A superspace approach to branes and supergravity (arXiv:hep-th/0007017)
Kurt Lechner, Mario Tonin, Superspace formulations of ten-dimensional supergravity, JHEP 0806:021,2008 (arXiv:0802.3869)
For d=4 N=1 supergravity the torsion is again constrained to be equal to the left-invariant torsion of super-Minkowski spacetime, see for instance
Leonardo Castellani, Riccardo D'Auria, Pietro Fré, volume 2, (III.2.28a), (III.3.66a) of Supergravity and Superstrings - A Geometric Perspective, World Scientific (1991)
Daniel Patrick Butter, section 2.2.5 of On conformal superspace and the One-Loop Effective Action in Supergravity, 2010 (pdf)
Last revised on January 11, 2019 at 07:25:22. See the history of this page for a list of all contributions to it.