FCGetScalarProducts[{p1, p2, ...}] returns all scalar
products involving external momenta p1, p2, ... that were
set using down values.
Using the option SetDimensions one can specify the
dimensions of scalar products one is interested in.
Overview, ScalarProduct, Pair, SP, SPD.
FCClearScalarProducts[];
SP[p1] = m1^2;
SP[p1] = m2^2;
SP[p1, p2] = s;
SPD[q1] = M1^2;
SPD[q2] = M2^2;
SPD[q1, q2] = t;FCGetScalarProducts[{p1, p2, q1, q2}]\left\{\text{Hold}[\text{Pair}]\left[\overline{\text{p1}},\overline{\text{p1}}\right]\to \;\text{m2}^2,\text{Hold}[\text{Pair}]\left[\overline{\text{p1}},\overline{\text{p2}}\right]\to s,\text{Hold}[\text{Pair}][\text{q1},\text{q1}]\to \;\text{M1}^2,\text{Hold}[\text{Pair}][\text{q2},\text{q2}]\to \;\text{M2}^2,\text{Hold}[\text{Pair}][\text{q1},\text{q2}]\to t\right\}
FCGetScalarProducts[{p1, p2, q1, q2}, SetDimensions -> {4}]\left\{\text{Hold}[\text{Pair}]\left[\overline{\text{p1}},\overline{\text{p1}}\right]\to \;\text{m2}^2,\text{Hold}[\text{Pair}]\left[\overline{\text{p1}},\overline{\text{p2}}\right]\to s\right\}
FCGetScalarProducts[{p1, p2, q1, q2}, SetDimensions -> {D}]\left\{\text{Hold}[\text{Pair}][\text{q1},\text{q1}]\to \;\text{M1}^2,\text{Hold}[\text{Pair}][\text{q2},\text{q2}]\to \;\text{M2}^2,\text{Hold}[\text{Pair}][\text{q1},\text{q2}]\to t\right\}