{ "id": "1307.3531", "version": "v2", "published": "2013-07-12T18:14:56.000Z", "updated": "2014-02-17T20:40:05.000Z", "title": "Average size of the 2-Selmer group of Jacobians of monic even hyperelliptic curves", "authors": [ "Arul Shankar", "Xiaoheng Wang" ], "comment": "arXiv admin note: text overlap with arXiv:1208.1007 by other authors", "categories": [ "math.NT", "math.AG" ], "abstract": "In [5], Manjul Bhargava and Benedict Gross considered the family of hyperelliptic curves over $\\Q$ having a fixed genus and a marked rational Weierstrass point. They showed that the average size of the 2-Selmer group of the Jacobians of these curves, when ordered by height, is 3. In this paper, we consider the family of hyperelliptic curves over $\\Q$ having a fixed genus and a marked rational non-Weierstrass point. We show that when these curves are ordered by height, the average size of the 2-Selmer group of their Jacobians is 6. This yields an upper bound of 5/2 on the average rank of the Mordell-Weil group of the Jacobians of these hyperelliptic curves. Finally using an equidistribution result, we modify the techniques of [16] to conclude that as $g$ tends to infinity, a proportion tending to 1 of these monic even-degree hyperelliptic curves having genus $g$ have exactly two rational points - the marked point at infinity and its hyperelliptic conjugate.", "revisions": [ { "version": "v2", "updated": "2014-02-17T20:40:05.000Z" } ], "analyses": { "keywords": [ "average size", "monic even-degree hyperelliptic curves", "marked rational non-weierstrass point", "fixed genus", "marked rational weierstrass point" ], "note": { "typesetting": "TeX", "pages": 0, "language": "en", "license": "arXiv", "status": "editable", "adsabs": "2013arXiv1307.3531S" } } }