{ "id": "1902.00096", "version": "v1", "published": "2019-01-31T22:11:15.000Z", "updated": "2019-01-31T22:11:15.000Z", "title": "A maximal function for families of Hilbert transforms along homogeneous curves", "authors": [ "Shaoming Guo", "Joris Roos", "Andreas Seeger", "Po-Lam Yung" ], "comment": "43 pages, submitted", "categories": [ "math.CA" ], "abstract": "Let $H^{(u)}$ be the Hilbert transform along the parabola $(t, ut^2)$ where $u\\in \\mathbb R$. For a set $U$ of positive numbers consider the maximal function $\\mathcal{H}^U \\!f= \\sup\\{|H^{(u)}\\! f|: u\\in U\\}$. We obtain an (essentially) optimal result for the $L^p$ operator norm of $\\mathcal{H}^U$ when $2