•The Overscript[J, _] part of the loops

We eliminate the Overscript[J, _]'s with equal masses and no denominator:

LoopJsExp = loopJs5 /. LeutwylerJBar[tu : (t | u), m1_, m2_ ? ((Head[#] =!= Rule) &), ___Rule] -> Jll[tu, m1, m2] /. _LeutwylerJBar -> 0 // Simplify

-1/(1152 t^2 u^2 π^2 (f _ ϕ^(ó  ))^4 (p _ 2^2 - (m _ K^(ó  ))^2)) (i c _ 5^( ) p _ 1^μ _ 1 µ _ μ _ 1(p _ 1) ((m _ π^(ó  ))^2 - (m _ K^(ó  ))^2) (4 π^2 Jll(t, (m _ K^(ó  ))^2, (m _ η^(ó  ))^2) (16 (m _ π^(ó  ))^8 - 2 (18 (m _ K^(ó  ))^2 + 2 s - 25 t + 2 u) (m _ π^(ó  ))^6 + (24 (m _ K^(ó  ))^4 + (8 s - 181 t + 8 u) (m _ K^(ó  ))^2 - t (7 s + 15 t + 11 u)) (m _ π^(ó  ))^4 + 2 (-2 (m _ K^(ó  ))^6 - 2 (s - 5 t + u) (m _ K^(ó  ))^4 + t (19 s + 60 t + 23 u) (m _ K^(ó  ))^2 - 3 t^2 (-3 s + 8 t + u)) (m _ π^(ó  ))^2 - 4 p _ 2^4 ((m _ π^(ó  ))^4 - 2 (m _ K^(ó  ))^2 (m _ π^(ó  ))^2 + (m _ K^(ó  ))^4 + 3 t^2 - 9 t (m _ K^(ó  ))^2) + t (3 (m _ K^(ó  ))^6 + (5 s + 3 t + u) (m _ K^(ó  ))^4 - 3 t (30 s + 17 t - 26 u) (m _ K^(ó  ))^2 + 9 t^2 (s + 5 t - 3 u)) + p _ 2^2 (-12 (m _ π^(ó  ))^6 + (28 (m _ K^(ó  ))^2 + 4 s - 5 t + 4 u) (m _ π^(ó  ))^4 - 2 (10 (m _ K^(ó  ))^4 + (4 s - 53 t + 4 u) (m _ K^(ó  ))^2 + 9 t^2) (m _ π^(ó  ))^2 + 4 (m _ K^(ó  ))^6 + (4 s - 29 t + 4 u) (m _ K^(ó  ))^4 - 6 t (6 s + 5 t + 6 u) (m _ K^(ó  ))^2 + 3 t^2 (4 s + t + 4 u))) u^2 - 12 π^2 Jll(t, (m _ π^(ó  ))^2, (m _ K^(ó  ))^2) (-48 (m _ π^(ó  ))^8 + 2 (54 (m _ K^(ó  ))^2 + 6 s + 5 t + 6 u) (m _ π^(ó  ))^6 - (72 (m _ K^(ó  ))^4 + (24 s + 17 t + 24 u) (m _ K^(ó  ))^2 - t (-11 s + 29 t + u)) (m _ π^(ó  ))^4 - 2 (-6 (m _ K^(ó  ))^6 - 2 (3 s + 13 t + 3 u) (m _ K^(ó  ))^4 + t (-7 s + 80 t + 5 u) (m _ K^(ó  ))^2 + t^2 (7 s - 52 t + 19 u)) (m _ π^(ó  ))^2 - t (9 (m _ K^(ó  ))^6 + (15 s + t + 3 u) (m _ K^(ó  ))^4 + t (-22 s - 105 t + 2 u) (m _ K^(ó  ))^2 + t^2 (-13 s + 95 t - 25 u)) + 4 p _ 2^4 (3 (m _ π^(ó  ))^4 - 2 (3 (m _ K^(ó  ))^2 + t) (m _ π^(ó  ))^2 + 3 (m _ K^(ó  ))^4 + 3 t^2 - t (m _ K^(ó  ))^2) - p _ 2^2 (-36 (m _ π^(ó  ))^6 + (84 (m _ K^(ó  ))^2 + 12 s + 17 t + 12 u) (m _ π^(ó  ))^4 - 2 (30 (m _ K^(ó  ))^4 + 3 (4 s - t + 4 u) (m _ K^(ó  ))^2 + t (4 s - 13 t + 4 u)) (m _ π^(ó  ))^2 + 12 (m _ K^(ó  ))^6 + (12 s + t + 12 u) (m _ K^(ó  ))^4 + 2 t (-2 s + 15 t - 2 u) (m _ K^(ó  ))^2 + t^2 (12 s - 23 t + 12 u))) u^2 + t (4 t π^2 Jll(u, (m _ K^(ó  ))^2, (m _ η^(ó  ))^2) (16 (m _ π^(ó  ))^8 - 2 (18 (m _ K^(ó  ))^2 + 2 s + 2 t - 25 u) (m _ π^(ó  ))^6 + (24 (m _ K^(ó  ))^4 + (8 s + 8 t - 181 u) (m _ K^(ó  ))^2 - u (7 s + 11 t + 15 u)) (m _ π^(ó  ))^4 + 2 (-2 (m _ K^(ó  ))^6 - 2 (s + t - 5 u) (m _ K^(ó  ))^4 + u (19 s + 23 t + 60 u) (m _ K^(ó  ))^2 + 3 (3 s - t - 8 u) u^2) (m _ π^(ó  ))^2 - 4 p _ 2^4 ((m _ π^(ó  ))^4 - 2 (m _ K^(ó  ))^2 (m _ π^(ó  ))^2 + (m _ K^(ó  ))^4 + 3 u^2 - 9 u (m _ K^(ó  ))^2) + u (3 (m _ K^(ó  ))^6 + (5 s + t + 3 u) (m _ K^(ó  ))^4 - 3 u (30 s - 26 t + 17 u) (m _ K^(ó  ))^2 + 9 u^2 (s - 3 t + 5 u)) + p _ 2^2 (-12 (m _ π^(ó  ))^6 + (28 (m _ K^(ó  ))^2 + 4 s + 4 t - 5 u) (m _ π^(ó  ))^4 - 2 (10 (m _ K^(ó  ))^4 + (4 s + 4 t - 53 u) (m _ K^(ó  ))^2 + 9 u^2) (m _ π^(ó  ))^2 + 4 (m _ K^(ó  ))^6 + (4 s + 4 t - 29 u) (m _ K^(ó  ))^4 - 6 u (6 s + 6 t + 5 u) (m _ K^(ó  ))^2 + 3 u^2 (4 s + 4 t + u))) - 12 t π^2 Jll(u, (m _ π^(ó  ))^2, (m _ K^(ó  ))^2) (-48 (m _ π^(ó  ))^8 + 2 (54 (m _ K^(ó  ))^2 + 6 s + 6 t + 5 u) (m _ π^(ó  ))^6 - (72 (m _ K^(ó  ))^4 + (24 s + 24 t + 17 u) (m _ K^(ó  ))^2 + (11 s - t - 29 u) u) (m _ π^(ó  ))^4 - 2 (-6 (m _ K^(ó  ))^6 - 2 (3 s + 3 t + 13 u) (m _ K^(ó  ))^4 + u (-7 s + 5 t + 80 u) (m _ K^(ó  ))^2 + (7 s + 19 t - 52 u) u^2) (m _ π^(ó  ))^2 - u (9 (m _ K^(ó  ))^6 + (15 s + 3 t + u) (m _ K^(ó  ))^4 + (-22 s + 2 t - 105 u) u (m _ K^(ó  ))^2 + u^2 (-13 s - 25 t + 95 u)) + 4 p _ 2^4 (3 (m _ π^(ó  ))^4 - 2 (3 (m _ K^(ó  ))^2 + u) (m _ π^(ó  ))^2 + 3 (m _ K^(ó  ))^4 + 3 u^2 - u (m _ K^(ó  ))^2) - p _ 2^2 (-36 (m _ π^(ó  ))^6 + (84 (m _ K^(ó  ))^2 + 12 s + 12 t + 17 u) (m _ π^(ó  ))^4 - 2 (30 (m _ K^(ó  ))^4 + 3 (4 s + 4 t - u) (m _ K^(ó  ))^2 + (4 s + 4 t - 13 u) u) (m _ π^(ó  ))^2 + 12 (m _ K^(ó  ))^6 + (12 s + 12 t + u) (m _ K^(ó  ))^4 + (12 s + 12 t - 23 u) u^2 + 2 u (-2 s - 2 t + 15 u) (m _ K^(ó  ))^2)) + u (3 ((t + u) (m _ π^(ó  ))^2 + 5 (t + u) (m _ K^(ó  ))^2 - 2 t u) p _ 2^4 - (-9 (t + u) (m _ π^(ó  ))^4 + (3 t^2 - 8 u t + 3 u^2 - 42 (t + u) (m _ K^(ó  ))^2 + 3 s (t + u)) (m _ π^(ó  ))^2 + 3 (5 (t + u) (m _ K^(ó  ))^4 + (5 t^2 + 8 u t + 5 u^2 + 5 s (t + u)) (m _ K^(ó  ))^2 + t u (47 s - 2 (t + u)))) p _ 2^2 + 3 (-4 (t + u) (m _ π^(ó  ))^6 + (t^2 + 10 u t + u^2 - 19 (t + u) (m _ K^(ó  ))^2 + s (t + u)) (m _ π^(ó  ))^4 + (5 (t + u) (m _ K^(ó  ))^4 + (5 t^2 + 8 u t + 5 u^2 + 5 s (t + u)) (m _ K^(ó  ))^2 - 20 s t u) (m _ π^(ó  ))^2 + t u (-35 s^2 + 9 (t + u) s + 5 (3 s + 2 (t + u)) (m _ K^(ó  ))^2 - 4 t u))))))

We arrange to have symmetric expressions in t and u:

LoopJsExp1 = LoopJsExp /. Pair[_LorentzIndex, ___] -> Sequence[] /. {Jll[t, a___] * b_ :> Jll[t, a] * (b /. MandelstamU -> -MandelstamS - MandelstamT + Pair[Momentum[p2], Momentum[p2]] + ParticleMass[Kaon]^2 + 2 ParticleMass[Pion]^2), Jll[u, a___] * b_ :> Jll[u, a] * (b /. MandelstamT -> -MandelstamS - MandelstamU + ParticleMass[Kaon]^2 + Pair[Momentum[p2], Momentum[p2]] + 2 ParticleMass[Pion]^2)} /. cancelS /. kaonOnShell /. _RenormalizationState -> Sequence[] // Simplify

1/(576 t^2 u^2 π^2 (f _ ϕ^(ó  ))^4 (p _ 2^2 - (m _ K^(ó  ))^2)) (i c _ 5^( ) ((m _ K^(ó  ))^2 - (m _ π^(ó  ))^2) (-72 π^2 Jll(t, (m _ π^(ó  ))^2, (m _ K^(ó  ))^2) (-2 (m _ π^(ó  ))^8 - 2 (t - 3 (m _ K^(ó  ))^2) (m _ π^(ó  ))^6 + (-6 (m _ K^(ó  ))^4 + 2 t (m _ K^(ó  ))^2 + t (t + u)) (m _ π^(ó  ))^4 + 2 ((m _ K^(ó  ))^6 + t (m _ K^(ó  ))^4 - t (6 t + u) (m _ K^(ó  ))^2 + t^2 (6 t - u)) (m _ π^(ó  ))^2 - t (t - (m _ K^(ó  ))^2) (-2 (m _ K^(ó  ))^4 + (t + u) (m _ K^(ó  ))^2 + t (9 t - u)) + 2 p _ 2^2 ((m _ π^(ó  ))^6 - 3 (m _ K^(ó  ))^2 (m _ π^(ó  ))^4 - 3 (t^2 - (m _ K^(ó  ))^4) (m _ π^(ó  ))^2 - (m _ K^(ó  ))^6 + 2 t^3 - t^2 (m _ K^(ó  ))^2)) u^2 - 8 π^2 Jll(t, (m _ K^(ó  ))^2, (m _ η^(ó  ))^2) (-2 (m _ π^(ó  ))^8 + 2 (3 (m _ K^(ó  ))^2 - 5 t + p _ 2^2) (m _ π^(ó  ))^6 + (-6 (m _ K^(ó  ))^4 + 30 t (m _ K^(ó  ))^2 + t (u - 7 t) + p _ 2^2 (4 t - 6 (m _ K^(ó  ))^2)) (m _ π^(ó  ))^4 + 2 ((m _ K^(ó  ))^6 - 9 t (m _ K^(ó  ))^4 + t (10 t - u) (m _ K^(ó  ))^2 + 3 t^2 (2 t + u) + p _ 2^2 (3 (m _ K^(ó  ))^4 - 10 t (m _ K^(ó  ))^2 - 3 t^2)) (m _ π^(ó  ))^2 - 2 (t + p _ 2^2) (m _ K^(ó  ))^6 + t (23 t + u + 16 p _ 2^2) (m _ K^(ó  ))^4 - 6 t^2 (2 t + 7 u - 3 p _ 2^2) (m _ K^(ó  ))^2 + 9 t^3 (u - t)) u^2 - t (72 t π^2 Jll(u, (m _ π^(ó  ))^2, (m _ K^(ó  ))^2) (-2 (m _ π^(ó  ))^8 - 2 (u - 3 (m _ K^(ó  ))^2) (m _ π^(ó  ))^6 + (-6 (m _ K^(ó  ))^4 + 2 u (m _ K^(ó  ))^2 + u (t + u)) (m _ π^(ó  ))^4 - 2 (-(m _ K^(ó  ))^6 - u (m _ K^(ó  ))^4 + u (t + 6 u) (m _ K^(ó  ))^2 + (t - 6 u) u^2) (m _ π^(ó  ))^2 - u (u - (m _ K^(ó  ))^2) (-2 (m _ K^(ó  ))^4 + (t + u) (m _ K^(ó  ))^2 + u (9 u - t)) + 2 p _ 2^2 ((m _ π^(ó  ))^6 - 3 (m _ K^(ó  ))^2 (m _ π^(ó  ))^4 - 3 (u^2 - (m _ K^(ó  ))^4) (m _ π^(ó  ))^2 - (m _ K^(ó  ))^6 + 2 u^3 - u^2 (m _ K^(ó  ))^2)) + 8 t π^2 Jll(u, (m _ K^(ó  ))^2, (m _ η^(ó  ))^2) (-2 (m _ π^(ó  ))^8 + 2 (3 (m _ K^(ó  ))^2 - 5 u + p _ 2^2) (m _ π^(ó  ))^6 + (-6 (m _ K^(ó  ))^4 + 30 u (m _ K^(ó  ))^2 + (t - 7 u) u + p _ 2^2 (4 u - 6 (m _ K^(ó  ))^2)) (m _ π^(ó  ))^4 + 2 ((m _ K^(ó  ))^6 - 9 u (m _ K^(ó  ))^4 + u (10 u - t) (m _ K^(ó  ))^2 + 3 u^2 (t + 2 u) + p _ 2^2 (3 (m _ K^(ó  ))^4 - 10 u (m _ K^(ó  ))^2 - 3 u^2)) (m _ π^(ó  ))^2 - 2 (u + p _ 2^2) (m _ K^(ó  ))^6 + u (t + 23 u + 16 p _ 2^2) (m _ K^(ó  ))^4 + 9 (t - u) u^3 - 6 u^2 (7 t + 2 u - 3 p _ 2^2) (m _ K^(ó  ))^2) + u (126 t u p _ 2^4 - (3 (t + u) (m _ π^(ó  ))^4 + (12 (t + u) (m _ K^(ó  ))^2 - 374 t u) (m _ π^(ó  ))^2 + 3 (-5 (t + u) (m _ K^(ó  ))^4 - 50 t u (m _ K^(ó  ))^2 + 64 t u (t + u))) p _ 2^2 + 3 ((t + u) (m _ π^(ó  ))^6 + (4 (t + u) (m _ K^(ó  ))^2 + 86 t u) (m _ π^(ó  ))^4 - (5 (t + u) (m _ K^(ó  ))^4 - 66 t u (m _ K^(ó  ))^2 + 89 t u (t + u)) (m _ π^(ó  ))^2 + t u (10 (m _ K^(ó  ))^4 - 37 (t + u) (m _ K^(ó  ))^2 + 22 t^2 + 22 u^2 + 46 t u))))))

The above expression contains Overscript[J, _] terms and polynomial terms, both of which are symmetric in u and t:

(LoopJsExp1) - (LoopJsExp1 /. {MandelstamU -> MandelstamT, MandelstamT -> MandelstamU, u -> t, t -> u}) // Expand

0

The numerator of the above expression. It must have an overall factor of t^2 u^2 in order to not have have unwanted poles.

probJ = LoopJsExp1 * MandelstamT^2 MandelstamU^2

1/(576 π^2 (f _ ϕ^(ó  ))^4 (p _ 2^2 - (m _ K^(ó  ))^2)) (i c _ 5^( ) ((m _ K^(ó  ))^2 - (m _ π^(ó  ))^2) (-72 π^2 Jll(t, (m _ π^(ó  ))^2, (m _ K^(ó  ))^2) (-2 (m _ π^(ó  ))^8 - 2 (t - 3 (m _ K^(ó  ))^2) (m _ π^(ó  ))^6 + (-6 (m _ K^(ó  ))^4 + 2 t (m _ K^(ó  ))^2 + t (t + u)) (m _ π^(ó  ))^4 + 2 ((m _ K^(ó  ))^6 + t (m _ K^(ó  ))^4 - t (6 t + u) (m _ K^(ó  ))^2 + t^2 (6 t - u)) (m _ π^(ó  ))^2 - t (t - (m _ K^(ó  ))^2) (-2 (m _ K^(ó  ))^4 + (t + u) (m _ K^(ó  ))^2 + t (9 t - u)) + 2 p _ 2^2 ((m _ π^(ó  ))^6 - 3 (m _ K^(ó  ))^2 (m _ π^(ó  ))^4 - 3 (t^2 - (m _ K^(ó  ))^4) (m _ π^(ó  ))^2 - (m _ K^(ó  ))^6 + 2 t^3 - t^2 (m _ K^(ó  ))^2)) u^2 - 8 π^2 Jll(t, (m _ K^(ó  ))^2, (m _ η^(ó  ))^2) (-2 (m _ π^(ó  ))^8 + 2 (3 (m _ K^(ó  ))^2 - 5 t + p _ 2^2) (m _ π^(ó  ))^6 + (-6 (m _ K^(ó  ))^4 + 30 t (m _ K^(ó  ))^2 + t (u - 7 t) + p _ 2^2 (4 t - 6 (m _ K^(ó  ))^2)) (m _ π^(ó  ))^4 + 2 ((m _ K^(ó  ))^6 - 9 t (m _ K^(ó  ))^4 + t (10 t - u) (m _ K^(ó  ))^2 + 3 t^2 (2 t + u) + p _ 2^2 (3 (m _ K^(ó  ))^4 - 10 t (m _ K^(ó  ))^2 - 3 t^2)) (m _ π^(ó  ))^2 - 2 (t + p _ 2^2) (m _ K^(ó  ))^6 + t (23 t + u + 16 p _ 2^2) (m _ K^(ó  ))^4 - 6 t^2 (2 t + 7 u - 3 p _ 2^2) (m _ K^(ó  ))^2 + 9 t^3 (u - t)) u^2 - t (72 t π^2 Jll(u, (m _ π^(ó  ))^2, (m _ K^(ó  ))^2) (-2 (m _ π^(ó  ))^8 - 2 (u - 3 (m _ K^(ó  ))^2) (m _ π^(ó  ))^6 + (-6 (m _ K^(ó  ))^4 + 2 u (m _ K^(ó  ))^2 + u (t + u)) (m _ π^(ó  ))^4 - 2 (-(m _ K^(ó  ))^6 - u (m _ K^(ó  ))^4 + u (t + 6 u) (m _ K^(ó  ))^2 + (t - 6 u) u^2) (m _ π^(ó  ))^2 - u (u - (m _ K^(ó  ))^2) (-2 (m _ K^(ó  ))^4 + (t + u) (m _ K^(ó  ))^2 + u (9 u - t)) + 2 p _ 2^2 ((m _ π^(ó  ))^6 - 3 (m _ K^(ó  ))^2 (m _ π^(ó  ))^4 - 3 (u^2 - (m _ K^(ó  ))^4) (m _ π^(ó  ))^2 - (m _ K^(ó  ))^6 + 2 u^3 - u^2 (m _ K^(ó  ))^2)) + 8 t π^2 Jll(u, (m _ K^(ó  ))^2, (m _ η^(ó  ))^2) (-2 (m _ π^(ó  ))^8 + 2 (3 (m _ K^(ó  ))^2 - 5 u + p _ 2^2) (m _ π^(ó  ))^6 + (-6 (m _ K^(ó  ))^4 + 30 u (m _ K^(ó  ))^2 + (t - 7 u) u + p _ 2^2 (4 u - 6 (m _ K^(ó  ))^2)) (m _ π^(ó  ))^4 + 2 ((m _ K^(ó  ))^6 - 9 u (m _ K^(ó  ))^4 + u (10 u - t) (m _ K^(ó  ))^2 + 3 u^2 (t + 2 u) + p _ 2^2 (3 (m _ K^(ó  ))^4 - 10 u (m _ K^(ó  ))^2 - 3 u^2)) (m _ π^(ó  ))^2 - 2 (u + p _ 2^2) (m _ K^(ó  ))^6 + u (t + 23 u + 16 p _ 2^2) (m _ K^(ó  ))^4 + 9 (t - u) u^3 - 6 u^2 (7 t + 2 u - 3 p _ 2^2) (m _ K^(ó  ))^2) + u (126 t u p _ 2^4 - (3 (t + u) (m _ π^(ó  ))^4 + (12 (t + u) (m _ K^(ó  ))^2 - 374 t u) (m _ π^(ó  ))^2 + 3 (-5 (t + u) (m _ K^(ó  ))^4 - 50 t u (m _ K^(ó  ))^2 + 64 t u (t + u))) p _ 2^2 + 3 ((t + u) (m _ π^(ó  ))^6 + (4 (t + u) (m _ K^(ó  ))^2 + 86 t u) (m _ π^(ó  ))^4 - (5 (t + u) (m _ K^(ó  ))^4 - 66 t u (m _ K^(ó  ))^2 + 89 t u (t + u)) (m _ π^(ó  ))^2 + t u (10 (m _ K^(ó  ))^4 - 37 (t + u) (m _ K^(ó  ))^2 + 22 t^2 + 22 u^2 + 46 t u))))))

Using the expansion of the Overscript[J, _]'s we see that this is indeed the case for the polynomial part:

probJ /. {MandelstamS -> s, MandelstamT -> t, MandelstamU -> u} /. u -> -s - t + ParticleMass[Kaon]^2 + Pair[Momentum[p2], Momentum[p2]] + 2 ParticleMass[Pion]^2 /. Jll -> Jl /. _Log -> 0 /. gellmannOkubo // Simplify

-(i t^2 c _ 5^( ) (2 (m _ π^(ó  ))^2 + (m _ K^(ó  ))^2 - s - t + p _ 2^2)^2 (-48 (m _ π^(ó  ))^8 + 4 (-225 (m _ K^(ó  ))^2 + 42 s + 24 t - 41 p _ 2^2) (m _ π^(ó  ))^6 + 2 (-36 p _ 2^4 + (-526 (m _ K^(ó  ))^2 + 159 s + 60 t) p _ 2^2 + 3 (-54 (m _ K^(ó  ))^4 + 3 (57 s + 92 t) (m _ K^(ó  ))^2 + s^2 - 8 t^2 - 32 s t)) (m _ π^(ó  ))^4 + (-9 p _ 2^6 + 9 (-75 (m _ K^(ó  ))^2 + 5 s + 4 t) p _ 2^4 - (1571 (m _ K^(ó  ))^4 - 12 (91 s + 148 t) (m _ K^(ó  ))^2 + 9 (7 s^2 + 12 t s + 4 t^2)) p _ 2^2 + 3 (-227 (m _ K^(ó  ))^6 + 3 (175 s + 44 t) (m _ K^(ó  ))^4 - (307 s^2 + 628 t s + 268 t^2) (m _ K^(ó  ))^2 + 3 s (3 s^2 + 8 t s + 8 t^2))) (m _ π^(ó  ))^2 + 3 (m _ K^(ó  ))^2 (-15 (m _ K^(ó  ))^6 + (91 s - 68 t) (m _ K^(ó  ))^4 + (-121 s^2 - 100 t s + 68 t^2) (m _ K^(ó  ))^2 - 39 p _ 2^6 + 3 s (15 s^2 + 56 t s + 56 t^2) + 3 p _ 2^4 (-31 (m _ K^(ó  ))^2 + 41 s + 52 t) + p _ 2^2 (59 (m _ K^(ó  ))^4 + (298 s + 88 t) (m _ K^(ó  ))^2 - 3 (43 s^2 + 108 t s + 52 t^2)))))/(1152 π^2 (f _ ϕ^(ó  ))^4 (p _ 2^2 - (m _ K^(ó  ))^2) ((m _ K^(ó  ))^2 - (m _ π^(ó  ))^2))

This is the potentially problematic logarithmic piece coming from the expansion of the Overscript[J, _]'s:

tmp1 = ((((probJ /. {MandelstamS -> s, MandelstamT -> t, MandelstamU -> u} /. Jll -> Jl) - (probJ /. {MandelstamS -> s, MandelstamT -> t, MandelstamU -> u} /. Jll -> Jl /. _Log -> 0)) /. gellmannOkubo // Expand) /. (t)^(_ ? ((# > 1) &)) (u)^(_ ? ((# > 1) &)) -> 0 /. cancelLogs // Simplify) /. cancelLogs // Simplify

-(i t u (t + u) c _ 5^( ) (p _ 2^2 - (m _ π^(ó  ))^2) (m _ K^(ó  ))^2 ((m _ π^(ó  ))^2 - (m _ K^(ó  ))^2) ((log((m _ π^(ó  ))^2/μ^2) + log(4/3 - (m _ π^(ó  ))^2/(3 (m _ K^(ó  ))^2)) - log((m _ K^(ó  ))^2/μ^2)) (m _ π^(ó  ))^2 - 4 log(4/3 - (m _ π^(ó  ))^2/(3 (m _ K^(ó  ))^2)) (m _ K^(ó  ))^2))/(64 π^2 (f _ ϕ^(ó  ))^4 (p _ 2^2 - (m _ K^(ó  ))^2))

Converted by Mathematica  (July 10, 2003)