The unramified principal series of -adic groups. I. The spherical function
Let be an additive form of degree with prime variables . Suppose that has real coefficients with at least one ratio algebraic and irrational. If s is large enough then takes values close to almost all members of any well-spaced sequence. This complements earlier work of Brüdern, Cook and Perelli (linear forms) and Cook and Fox (quadratic forms). The result is based on Hua’s Lemma and, for , Heath-Brown’s improvement on Hua’s Lemma.