A Note on Almost Everywhere Convergence Along Tangential Curves to the Schr\"odinger Equation Initial Datum

Abstract

In this short note, we give an easy proof of the following result: for $ n\geq 2, $ $\underset{t\to0}{\lim} \,e^{it\Delta }f\left(x+\gamma(t)\right) = f(x) $ almost everywhere whenever $ \gamma $ is an $ \alpha- $H\"older curve with $ \frac12\leq \alpha\leq 1 $ and $ f\in H^s(\mathbb{R}^n) $, with $ s > \frac{n}{2(n+1)} $. This is the optimal range of regularity up to the endpoint.