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\newtheorem{prop}{Proposition} \newtheorem{cor}{Corollary} \newtheorem*{utheorem}{Theorem} \newtheorem*{ulemma}{Lemma} \newtheorem*{uprop}{Proposition} \newtheorem*{ucor}{Corollary} \theoremstyle{definition} \newtheorem{defn}{Definition} \newtheorem{example}{Example} \newtheorem*{udefn}{Definition} \newtheorem*{uexample}{Example} \theoremstyle{remark} \newtheorem{remark}{Remark} \newtheorem{note}{Note} \newtheorem*{uremark}{Remark} \newtheorem*{unote}{Note} %------------------------------------------------------------------- \begin{document} %------------------------------------------------------------------- \section*{supergravity Lie 6-algebra} \hypertarget{context}{}\subsubsection*{{Context}}\label{context} \hypertarget{lie_theory}{}\paragraph*{{$\infty$-Lie theory}}\label{lie_theory} [[!include infinity-Lie theory - contents]] \hypertarget{string_theory}{}\paragraph*{{String theory}}\label{string_theory} [[!include string theory - contents]] \hypertarget{supergeometry}{}\paragraph*{{Super-Geometry}}\label{supergeometry} [[!include supergeometry - contents]] \hypertarget{contents}{}\section*{{Contents}}\label{contents} \noindent\hyperlink{idea}{Idea}\dotfill \pageref*{idea} \linebreak \noindent\hyperlink{definition}{Definition}\dotfill \pageref*{definition} \linebreak \noindent\hyperlink{RelationToSupergravity}{Relation to $D = 11$ supergravity}\dotfill \pageref*{RelationToSupergravity} \linebreak \noindent\hyperlink{related_concepts}{Related concepts}\dotfill \pageref*{related_concepts} \linebreak \noindent\hyperlink{references}{References}\dotfill \pageref*{references} \linebreak \hypertarget{idea}{}\subsection*{{Idea}}\label{idea} The \emph{supergravity Lie 6-algebra} is a [[super L-∞ algebra]] such that [[connection on an ∞-bundle|∞-connections]] with values in it encode \begin{itemize}% \item a [[vielbein]] field and a [[spin connection]], hence the [[first order formulation of gravity]] for a [[graviton]] field in 11-[[dimension]]s; \item a [[gravitino]] field; \item the [[supergravity C-field]] in degree 3 \emph{and} its [[electric-magnetic duality|magnetic dual]]. \end{itemize} This is such that the [[field strength]]s and [[Bianchi identities]] of these fields are governed by certain fermionic [[L-∞ algebra cohomology|super L-∞ algebraic cocycles]] as suitable for [[11-dimensional supergravity]]. \hypertarget{definition}{}\subsection*{{Definition}}\label{definition} \begin{prop} \label{TheSevenCocycle}\hypertarget{TheSevenCocycle}{} The [[supergravity Lie 3-algebra]] $\mathfrak{sugra}_3(10,1)$ carries an [[L-∞ algebra cohomology|L-∞ algebra cocycle]] $\mu_7 \in CE(\mathfrak{sugra}_3(10,1))$ of degree 7, given in the standard generators $\{e^a\}$ ([[vielbein]]), $\{\omega^{a b}\}$ ([[spin connection]]) $\{\psi^\alpha\}$ ([[gravitino]]) and $\{c_3\}$ ([[supergravity C-field]]) by \begin{displaymath} \mu_7 \coloneqq \frac{i}{2}\bar \psi \wedge \Gamma^{a_1 \cdots a_5} \psi \wedge e_{a_1} \wedge \cdots \wedge e_{a_5} + 15 \mu_4 \wedge c_3 \,, \end{displaymath} where \begin{displaymath} \mu_4 = \frac{i}{2}\bar \psi \Gamma^{a_1 a_2} \psi \wedge e_{a_1} \wedge e_{a_2} \end{displaymath} is the 4-cocycle which defines $\mathfrak{sugra}_3(10,1)$ as an extension of $\mathbb{R}^{10,1\vert \mathbf{32}}$m and where $c_3$ is the generator that cancels the class of this cocycle, $d_{CE} c_3 \propto \mu_4$. \end{prop} This appears in (\hyperlink{DAuriaFre}{DAuria-Fre, page 18}) and \hyperlink{CastellaniDAuriaFre}{Castellani-DAuria-Fre, III.8.3}. \begin{proof} One computes \begin{displaymath} \begin{aligned} d_{CE} \mu_7 = & - \frac{5}{4} \bar \psi \wedge \Gamma^{a_1 \cdots a_4 b} \psi \wedge e_{a_1} \wedge \cdots \wedge e_{a_4} \wedge \bar \psi \wedge \Gamma_b \psi \\ & - i 15 \wedge \Gamma^{a b} e_a \wedge \bar \psi \wedge \Gamma_b \psi \wedge c_3 \\ & + \frac{15}{4} \bar \psi \wedge \Gamma_{a b} \psi \wedge e^a \wedge e^b \wedge \bar \psi \wedge \Gamma_{c d} \psi \wedge e^c \wedge e^d \end{aligned} \,. \end{displaymath} This expression vanishes due to the [[Fierz identities]] \begin{displaymath} \bar \psi \wedge \Gamma^{a_1 \cdots a_4 b} \psi \wedge \bar \psi \wedge \Gamma_b \psi = 3 \bar \psi \wedge \Gamma^{[a_1 a_2} \psi \wedge \bar \psi \wedge \Gamma^{a_3 a_4 ]} \psi \end{displaymath} and \begin{displaymath} \bar \psi \wedge \Gamma^{a b} \psi \wedge \bar \psi \wedge \Gamma_b \psi = 0 \,. \end{displaymath} \end{proof} \begin{remark} \label{}\hypertarget{}{} Hence if we write \begin{displaymath} g_4 \coloneqq \mu_4 = \bar \psi \Gamma^{a_1 a_2} \psi \wedge e_{a_1} \wedge e_{a_2} \end{displaymath} and \begin{displaymath} g_7 \coloneqq \bar \psi \wedge \Gamma^{a_1 \cdots a_5} \psi \wedge e_{a_1} \wedge \cdots \wedge e_{a_5} \end{displaymath} then \begin{displaymath} d g_7 \propto g_4 \wedge g_4 \,. \end{displaymath} This is the structure of the [[equations of motion]] of the [[field strength]] $G_4$ of the [[supergravity C-field]] and its [[Hodge dual]] $G_7 = \ast G_4$ in [[11-dimensional supergravity]]. \end{remark} \begin{def} \label{TheDefinition}\hypertarget{TheDefinition}{} The \emph{supergravity Lie 6-algebra} $\mathfrak{sugra}_{7}(10,1)$ is the [[super L-∞ algebra|super Lie 7-algebra]] that is the $b^6 \mathbb{R}$-[[L-∞ algebra cohomology|extension]] of $\mathfrak{sugra}_3(10,1)$ classified by the cocycle $\mu_7$ from def. \ref{TheSevenCocycle}. \begin{displaymath} b^5 \mathbb{R} \to \mathfrak{sugra}_6 \to \mathfrak{sugra}_3 \,. \end{displaymath} \end{def} \begin{remark} \label{InTermsOfGenerators}\hypertarget{InTermsOfGenerators}{} This means that the [[Chevalley-Eilenberg algebra]] $CE(\mathfrak{sugra}_6)$ is generated from \begin{itemize}% \item $\{e^a\}$ ([[vielbein]]) in degree $(1,even)$ \item $\{\omega^{a b}\}$ ([[spin connection]]) in degree $(1,even)$; \item $\{\psi^\alpha\}$ ([[gravitino]]) in degree $(1,odd)$ \item $\{c_3\}$ ([[supergravity C-field]]) in degree $(3,even)$ \item $\{c_6\}$ (magnetic dual [[supergravity C-field]]) in degree $(6,even)$ \end{itemize} with [[differential]] defined by \begin{displaymath} d_{CE} : \omega^{a b} \mapsto \omega^{a c} \wedge \omega_c{}^b \end{displaymath} \begin{displaymath} d_{CE} : e^a = -\omega^{a b} e_b - \frac{1}{2}i \bar \psi \wedge \Gamma^a \psi \end{displaymath} \begin{displaymath} d_{CE} : \psi \mapsto - \frac{1}{4}\omega^{a b} \Gamma^{a b} \end{displaymath} \begin{displaymath} d_{CE} : c_3 \mapsto \frac{1}{2} \bar \psi \wedge \Gamma^{a b} \psi \wedge e_a \wedge e_b \end{displaymath} \begin{displaymath} d_{CE} \colon c_6 \mapsto - \frac{1}{2} \bar \psi \wedge \Gamma^{a_1 \cdots a_5} \psi \wedge e_{a_1} \wedge \cdots \wedge e_{a_5} - \frac{13}{2} \bar \psi \Gamma^{a_1 a_2} \psi \wedge e_{a_1} \wedge e_{a_2} \wedge c_3 \,. \end{displaymath} \end{remark} This appears as (\hyperlink{CastellaniDAuriaFre}{Castellani-DAuria-Fre, (III.8.18)}). \begin{remark} \label{}\hypertarget{}{} According to (\hyperlink{CastellaniDAuriaFre}{Castellani-DAuria-Fre, comment below (III.8.18)}): ``no further extension is possible''. \end{remark} \hypertarget{RelationToSupergravity}{}\subsection*{{Relation to $D = 11$ supergravity}}\label{RelationToSupergravity} The supergravity Lie 6-algebra is something like the gauge $L_\infty$-algebra of [[11-dimensional supergravity]], in the sense discussed at \emph{[[D'Auria-Fre formulation of supergravity]]} . \begin{defn} \label{ModifiedWeilAlgebra}\hypertarget{ModifiedWeilAlgebra}{} Write $W(\mathfrak{sugra}_6(10,1))$ for the [[Weil algebra]] of the supergravity Lie 6-algebra. Write $g_4$ and $g_7$ for the shifted generators of the Weil algebra corresponding to $c_3$ and $c_6$, respectively. Define a modified Weil algebra $\tilde W(\mathfrak{sugra}_6(10,1))$ by declaring it to have the same generators and differential as before, except that the differential for $c_6$ is modified to \begin{displaymath} d_{\tilde W} c_6 := d_{W} c_6 + 15 g_4 \wedge c_3 \end{displaymath} and hence the differential of $g_7$ is accordingly modified in the unique way that ensures $d_{\tilde W}^2 = 0$ (yielding the modified [[Bianchi identity]] for $g_7$). \end{defn} This ansatz appears as (\hyperlink{CastellaniDAuriaFre}{CastellaniDAuriaFre, (III.8.24)}). Note that this amounts simply to a redefinition of [[curvature]]s \begin{displaymath} \tilde g_7 := g_7 + 15 g_4 \wedge c_3 \,. \end{displaymath} \begin{note} \label{SugraEOM}\hypertarget{SugraEOM}{} A field configuration of [[11-dimensional supergravity]] is given by [[∞-groupoid of ∞-Lie algebra valued forms|L-∞ algebra valued differential forms]] with values in $\mathfrak{sugra}_6$. Among all of these the solutions to the equations of motion (the points in the [[covariant phase space]]) can be characterized as follows: A field configuration \begin{displaymath} \Omega^\bullet(X) \leftarrow \tilde W(\mathfrak{sugra}_6) : \Phi \end{displaymath} solves the equations of motion precisely if \begin{enumerate}% \item all [[curvature]]s sit in the ideal of differential forms spanned by the 1-form fields $E^a$ ([[vielbein]]) and $\Psi$ ([[gravitino]]); more precisely if we have \begin{itemize}% \item $\tau = 0$ (super-[[torsion]]); \item $G_4 = (G_4)_{a_1, \cdots a_4} E^{a_1} \wedge \cdots E^{a_4}$ ([[field strength]] of [[supergravity C-field]]) \item $G_7 = (G_7)_{a_1, \cdots a_7} E^{a_1} \wedge \cdots E^{a_7}$ ([[electric-magnetic duality|dual]] field strength) \item $\rho = \rho_{a b} E^a \wedge E^b + H_a \Psi \wedge E^a$ ([[Dirac operator]] applied to [[gravitino]]) \item $R^{a b} = R^{a b}_{c d} E^c \wedge E^d + \bar \Theta^{a b}{}_c \Psi \wedge E^c + \bar \Psi \wedge K^{a b} \Psi$ ([[Riemann tensor]]: [[field strength]] of [[gravity]]) \end{itemize} \item such that the coefficients of terms containing $\Psi$s are polynomials in the coefficients of the terms containing no $\Psi$s. (``rheonomy''). \end{enumerate} \end{note} This is the content of (\hyperlink{CastellaniDAuriaFre}{CastellaniDAuriaFre, section III.8.5}). In particular this implies that on-shell the 4- and 7-field strength are indeed dual of each other \begin{displaymath} G_7 \propto \star G_4 \,. \end{displaymath} This is the content of (\hyperlink{CastellaniDAuriaFre}{CastellaniDAuriaFre, equation (III.8.52)}). \hypertarget{related_concepts}{}\subsection*{{Related concepts}}\label{related_concepts} \textbf{supergravity Lie 6-algebra} $\to$ [[supergravity Lie 3-algebra]] $\to$ [[super Poincaré Lie algebra]] \begin{itemize}% \item [[4d supergravity Lie 2-algebra]] \item [[type II supergravity Lie 2-algebra]] \item [[M-theory super Lie algebra]] \end{itemize} \hypertarget{references}{}\subsection*{{References}}\label{references} The supergravity Lie 6-algebra appears first on page 18 of \begin{itemize}% \item [[Riccardo D'Auria]], [[Pietro Fré]]; \emph{[[GeometricSupergravity.pdf:file]]}, Nuclear Physics B201 (1982) 101-140 \end{itemize} and is recalled in section 4 of \begin{itemize}% \item [[Leonardo Castellani]], [[Pietro Fré]], F. Giani, K. Pilch, [[Peter van Nieuwenhuizen]], \emph{Gauging of $d = 11$ supergravity?}, Annals of Physics Volume 146, Issue 1, March 1983, Pages 35--77 \end{itemize} A textbook discussion is in section III.8.3 of \begin{itemize}% \item [[Leonardo Castellani]], [[Riccardo D'Auria]], [[Pietro Fre]], \emph{[[Supergravity and Superstrings - A Geometric Perspective]]} \end{itemize} The same is being recalled for instance in section 3 of \begin{itemize}% \item [[Pietro Fré]], Pietro Antonio Grassi, \emph{Free Differential Algebras, Rheonomy, and Pure Spinors} (\href{http://arxiv.org/abs/0801.3076}{arXiv:0801.3076}) \end{itemize} Then it is rediscovered around equation (8.8) in \begin{itemize}% \item C. Chryssomalakos, [[José de Azcárraga]], J. M. Izquierdo and C. P\'e{}rez Bueno, \emph{The geometry of branes and extended superspaces} (\href{http://arxiv.org/abs/hep-th/9904137}{arXiv:hep-th/9904137}) \end{itemize} which gives a detailed and comprehensive discussion. A discussion in the context of [[smooth super ∞-groupoids]] is in \begin{itemize}% \item [[Domenico Fiorenza]], [[Hisham Sati]], [[Urs Schreiber]], \emph{[[schreiber:The brane bouquet|Super Lie n-algebra extensions, higher WZW models and super p-branes with tensor multiplet fields]]} \end{itemize} in the last section of \begin{itemize}% \item [[Urs Schreiber]], \emph{[[schreiber:differential cohomology in a cohesive topos]]} \end{itemize} \end{document}