On an oscillatory integral involving a homogeneous form

TL;DR

This paper establishes decay estimates for oscillatory integrals involving homogeneous forms with specific geometric conditions, extending understanding of their behavior in harmonic analysis.

Contribution

It proves a uniform decay bound for a class of oscillatory integrals associated with homogeneous forms under certain geometric and singularity conditions.

Findings

Decay rate of the integral is bounded by min{1, |τ|^{-1}}.

The result applies to forms with a singular locus of controlled dimension.

The proof relies on geometric and harmonic analysis techniques.

Abstract

Let $F \in \mathbb{R}[x_1, \ldots, x_n]$ be a homogeneous form of degree $d > 1$ satisfying $(n - \dim V_{F}^*) > 4$, where $V_F^*$ is the singular locus of $V(F) = \{ \mathbf{z} \in {\mathbb{C}}^n: F(\mathbf{z}) = 0 \}$. Suppose there exists $\mathbf{x}_0 \in (0,1)^n \cap (V(F) \backslash V_F^*)$. Let $\mathbf{t} = (t_1, \ldots, t_n) \in \mathbb{R}^n$. Then for a smooth function $\varpi:\mathbb{R}^n \rightarrow \mathbb{R}$ with its support contained in a small neighbourhood of $\mathbf{x}_0$, we prove $$ \Big{|} \int_{0}^{\infty} \cdots \int_{0}^{\infty} \varpi(\mathbf{x}) x_1^{i t_1} \cdots x_n^{i t_n} e^{2 \pi i \tau F(\mathbf{x})} d \mathbf{x} \Big{|} \ll \min \{ 1, |\tau|^{-1} \}, $$ where the implicit constant is independent of $\tau$ and $\mathbf{t}$.