Suppose there is the (pseudo)scalar field ˆθ with non-zero VEV θ, which effectively emerges at energy scale Λ (for example, the mass of some fermion, the scale of SSB and so on). An example is axion-like field θ, which is present as
∫θfγF∧F,fγ≃α−1EMΛ
in effective action (with
F denoting gauge field strength).
May the quantity
ϵ≡θΛ
be many times larger than one? I.e., does some condition exist, which forbids
ϵ>>1 domain? Or this is the question of our wishes, and there are no restrictions on value of
ϵ?