Mean values of the parameters , with X = T and Y = E, B (blue and red, respectively) in bins of the multipole l (with 1 − σ errors in colored shades) for the model in which the observer is located within the helical structure of the magnetic field. The diagrams change from left to right for models with α_b = −20%, 0%, and +20%. A weak left-handed helical magnetic field would produce positive T–B and T–E correlations.