SigTau - my new Asymptotic notation

I want to introduce a new asymptotic notation called SigTau (In greek S is Sigma and T is Tau).
S SigTau(T) means that if S increases then T increases by a portion of S (If S increases by 100% then T increases by 30%). If S decreases then T decreases by a significantly larger ratio (If S decreases by 20, then T decreases by 10 * 20). I am modelling this asymptotics based on the relationship Security holds with Trust. If Security incidents are reported then Trust on the product / service goes down by a drastic proportion. Meanwhile good score cards of Security builds trust in an evolutionary manner.
Note: SigTau is my fable and doesnt exist in theory.