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There is this paper: http://digital.csic.es/bitstream/10261/43192/1/p6374_1.pdf

In equation (36) of this, the second line ($\omega^{+ij} =\dots$), there is a term $\partial_{[i}\bar\lambda\delta_{j\,]k}$ that I didn't understand. What does this notation mean?

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    $\begingroup$ see en.wikipedia.org/wiki/Antisymmetric_tensor#Notation $\endgroup$ – Christoph Nov 22 '14 at 18:49
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    $\begingroup$ As Christoph said, this is antisymmetric notation, but be cautious. Sometimes people don't use $n!$ multiplication in front of it. So, up to $n!$ or $1/n!$, $A_{[i}B_{j]}=A_iB_j-A_jB_i$ $\endgroup$ – MEDVIS Nov 22 '14 at 18:55
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    $\begingroup$ Related: physics.stackexchange.com/q/79157/2451 $\endgroup$ – Qmechanic Nov 22 '14 at 18:56
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    $\begingroup$ @Fluctuations: $\delta_{jk}$ is the Kronecker-delta (a rank-2 tensor), but you only anti-symmetrize over one of its indices, leaving $k$ fixed $\endgroup$ – Christoph Nov 22 '14 at 19:14
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    $\begingroup$ @Fluctuations: Right (modulo a factor of $1/2$ depending on the chosen convention) $\endgroup$ – Christoph Nov 22 '14 at 19:21