In the context of a scientific paper, I would read 'associated with' as meaning 'related to in some way'. 'Corresponding to' on the other hand is more strictly defined - it implies a one-to-one relationship. x and y values on a graph would be a good example - for every value of x, there is a corresponding value y.
In your example:
group 'T' which has fields T1, T2, … Tn.
Neither seems to be the case. I would suggest something along the lines of:
...group 'T' which is comprised of fields T1, T2, … Tn.
...group 'T' which is composed of fields T1, T2, … Tn.
...group 'T' which ranges from T1, T2, … Tn.