We give lower bounds for the slope of higher dimensional fibrations over curves under conditions of GIT-semistability of the fibres, using a generalization of a method of Cornalba and Harris. With the same method we establish a sharp lower bound for the slope of trigonal fibrations of even genus and general Maroni invariant; this result in particular proves a conjecture due to Harris and Stankova-Frenkel.
@article{ASNSP_2009_5_8_4_647_0,
author = {Barja, Miguel \'Angel and Stoppino, Lidia},
title = {Slopes of trigonal fibred surfaces and of higher dimensional fibrations},
journal = {Annali della Scuola Normale Superiore di Pisa - Classe di Scienze},
pages = {647--658},
publisher = {Scuola Normale Superiore, Pisa},
volume = {Ser. 5, 8},
number = {4},
year = {2009},
zbl = {1204.14017},
mrnumber = {2647907},
language = {en},
url = {http://www.numdam.org/item/ASNSP_2009_5_8_4_647_0/}
}
Barja, Miguel Ángel; Stoppino, Lidia. Slopes of trigonal fibred surfaces and of higher dimensional fibrations. Annali della Scuola Normale Superiore di Pisa - Classe di Scienze, Série 5, Tome 8 (2009) no. 4, pp. 647-658. http://www.numdam.org/item/ASNSP_2009_5_8_4_647_0/
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