In[29]:=
  Solve[%==0,CD[sigma,la,lb,lc,ld,le,lf]]

Out[29]=

  {{sigma        -> 
         ;abcdef
   
      (-9 R        - 9 R        - 9 R        - 9 R        - 9 R        - 
           acbd;ef      acbe;df      acbf;de      adbc;ef      adbe;cf
   
         9 R        - 9 R        - 9 R        - 9 R        - 9 R        - 
            adbf;ce      aebc;df      aebd;cf      aebf;cd      afbc;de
   
                                             p             p             p
         9 R        - 9 R        + R     R     + R     R     + R     R     + 
            afbd;ce      afbe;cd    pdcf  abe     pdce  abf     pecd  abf
   
                   p             p             p             p             p
         R     R     + R     R     + R     R     + R     R     + R     R     + 
          pdbf  ace     pdbe  acf     pebd  acf     pcbf  ade     pcbe  adf
   
                   p             p             p             p             p
         R     R     + R     R     + R     R     + R     R     + R     R     + 
          pebc  adf     pcbf  aed     pcbd  aef     pdbc  aef     pcbe  afd
   
                   p             p             p               p
         R     R     + R     R     + 3 R     R     + 3 R     R     + 
          pcbd  afe     pdbc  afe       pedf  a bc      pfde  a bc
   
                   p               p               p               p
         3 R     R     + 3 R     R     + 3 R     R     + 3 R     R     + 
            pecf  a bd      pfce  a bd      pdcf  a be      pfcd  a be
   
                   p               p               p               p
         3 R     R     + 3 R     R     + 3 R     R     + 3 R     R     + 
            pdce  a bf      pecd  a bf      pebf  a cd      pfbe  a cd
   
                   p               p               p               p
         3 R     R     + 3 R     R     + 3 R     R     + 3 R     R     + 
            pdbf  a ce      pfbd  a ce      pdbe  a cf      pebd  a cf
   
                   p               p               p               p
         3 R     R     + 3 R     R     + 3 R     R     + 3 R     R     + 
            pcbf  a de      pfbc  a de      pcbe  a df      pebc  a df
   
                   p               p               p             p
         3 R     R     + 3 R     R     + R     R     + R     R     + 
            pcbd  a ef      pdbc  a ef    pdaf  bce     pdae  bcf
   
                   p             p             p             p             p
         R     R     + R     R     + R     R     + R     R     + R     R     + 
          pead  bcf     pcaf  bde     pcae  bdf     peac  bdf     pcaf  bed
   
                   p             p             p             p             p
         R     R     + R     R     + R     R     + R     R     + R     R     + 
          pcad  bef     pdac  bef     pcae  bfd     pcad  bfe     pdac  bfe
   
                   p               p               p               p
         3 R     R     + 3 R     R     + 3 R     R     + 3 R     R     + 
            peaf  b cd      pfae  b cd      pdaf  b ce      pfad  b ce
   
                   p               p               p               p
         3 R     R     + 3 R     R     + 3 R     R     + 3 R     R     + 
            pdae  b cf      pead  b cf      pcaf  b de      pfac  b de
   
                   p               p               p               p
         3 R     R     + 3 R     R     + 3 R     R     + 3 R     R     + 
            pcae  b df      peac  b df      pcad  b ef      pdac  b ef
   
                   p             p             p             p             p
         R     R     + R     R     + R     R     + R     R     + R     R     + 
          pbaf  cde     pbae  cdf     peab  cdf     pbaf  ced     pbad  cef
   
                   p             p             p             p
         R     R     + R     R     + R     R     + R     R     - 
          pdab  cef     pbae  cfd     pbad  cfe     pdab  cfe
   
                   p               p               p               p
         6 R     R     + 3 R     R     - 6 R     R     + 3 R     R     - 
            pbaf  c de      pfab  c de      pbae  c df      peab  c df
   
                   p               p               p             p
         6 R     R     + 3 R     R     + R     R     + R     R     + 
            pbad  c ef      pdab  c ef    pbac  def     pcab  def
   
                   p             p             p               p
         R     R     + R     R     - 6 R     R     + 3 R     R    ) / 45}}
          pbac  dfe     pcab  dfe       pbac  d ef      pcab  d ef

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