Complex sentence: The symmetry associated with weak isospin is SU (2) and requires gauge bosons with integral T_3 (and) to mediate transformations between fermions with half-integer weak isospin charges.
Split into simpler sentences: The symmetry associated with weak isospin is SU (2). This requires gauge bosons with integral T_3 (and) to mediate transformations between fermions with half-integer weak isospin charges.