Solve[%==0,CD[sigma,la,lb,lc,ld,le]]

Out[21]=

                   -R       - R       - R       - R       - R       - R
                     acbd;e    acbe;d    adbc;e    adbe;c    aebc;d    aebd;c
  {{sigma       -> ----------------------------------------------------------}}
         ;abcde                                4

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