Equation Icon  ( [ ] ~ V~ --- mn -1- ~ 1-~ mn ab L = - ~g ~g 2k Rmn - 2G(f)@mf @nf - U (f) ~g ~g Fma Fnb --[ ( ) ] ) +y~ i~emga @m + ~_O_m + qAm - ~M (f) ~y , (28) a