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Minimal fourth order operator


Code

Let' s calculate one-loop counterterms of minimal fourth order operator using methods described in Calculating one-loop counterterms. The operator is: Dij=δij2+Wμνijμν+Mij

The input quantities needed for the algorithm described in Calculating one-loop counterterms are: Kλμγδαβ=δβα13(gλμgγδ+gλγgμδ+gλδgμγ),Sμνγαβ=0,Wμναβ=Wμναβ,Nμαβ=0,Mαβ=Mαβ,(Kn)1αβ=δβα,Fμναβ=Fμναβ.

The following code produces the result:

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//setup symmetries of Riemann tensor
addSymmetries 'R_abcd', -[[0, 1]].p, [[0, 2], [1, 3]].p
setSymmetric 'R_ab'
addSymmetry 'W_lmab', [[0, 1]].p
 
def iK = 'iK_a^b = d_a^b'.t
def K = ('K^lmcd_a^b = d_a^b*1/3*(g^lm*g^cd + g^lc*g^md + g^ld*g^mc)').t
def S = 'S^lmpab = 0'.t
def W = 'W^lm_a^b = W^lm_a^b'.t
def N = 'N^pab=0'.t
def M = 'M_a^b = M_a^b'.t
def F = 'F_lmab = F_lmab'.t
 
def div = oneloopdiv4(iK, K, S, W, N, M, F)
def counterterms = EliminateDueSymmetries >> div.counterterms
counterterms = 'M^l_l = M'.t >> counterterms
counterterms = 'W_lm^a_a = W_lm'.t >> counterterms
counterterms = 'W^a_a = W'.t >> counterterms
println counterterms
> counterterms = (2/3)*F_{mb}^{e}_{a_{5}}*F^{mba_{5}}_{e}-(1/9)*W^{lm}*R_{lm}
          +(1/9)*R*W-M+(1/24)*W^{bda}_{a_{5}}*W_{bd}^{a_{5}}_{a}
          +(1/48)*W_{d}^{da}_{a_{5}}*W_{b}^{ba_{5}}_{a}
          -(32/135)*R^{al}*R_{al}+(44/135)*R**2

Multiplying the produced result by 1/16π(d4) and integrating over the space-time volume gives:

Γ(1)=116π(d4)d4xg(M+23FνβϵρFνβρϵ32135RμνRμν+44135R2+19RW19RμνWμν+124WϵδαρWϵδρα+148WδδαρWββρα),

where Fμναβ is a curvature tensor with respect to the principal bundle, Rμν is a Ricci tensor, R is a Riemann scalar curvature, Mμμ=M, Wμναα=Wμν and Wαα=W.

See also