DEURING'S MASS FORMULA OF A MUMFORD FAMILY.

We study the Newton polygon jumping locus of a Mumford family in char p. Our main result says that, under a mild assumption on p, the jumping locus consists of only supersingular points and its cardinality is equal to (pr - 1)(g - 1), where r is the degree of the defining field of the base curve of a Mumford family in char p and g is the genus of the curve. The underlying technique is the p-adic Hodge theory. [ABSTRACT FROM AUTHOR]