Ideas underlying the proof
of the “simple” trace formula are used to show the following. Let F be a global field,
and 𝔸 its ring of adeles. Let π be a cuspidal representation of GL(n, 𝔸) which has a
supercuspidal component, and ω a unitary character of 𝔸×∕F×. Let s0 be a complex
number such that for every separable extension E of F of degree n, the
L-function L(s,ω ∘NormE∕F) over E vanishes at s = s0 to the order m ≥ 0.
Then the product L-function L(s,π ⊗ ω ×π) vanishes at s = s0 to the order
m. This result is a reflection of the fact that the tensor product of a finite
dimensional representation with its contragredient contains a copy of the trivial
representation.