The LMS JCM, (11) 326-342. Published 29 Oct 2008. First received 22 Jan 2008.


Explicit calculations of automorphic forms for definite unitary groups

David Loeffler



Abstract: I give an algorithm for computing the full space of automorphic forms for definite unitary groups over Q, and apply this to calculate the automorphic forms of level G(hat{Z}) and various small weights for an example of a rank 3 unitary group. This leads to some examples of various types of endoscopic lifting from automorphic forms for U1 x U1 x U1 and U1 x U1, and to an example of a non-endoscopic form of weight (3,3) corresponding to a family of 3-dimensional irreducible l-adic Galois representations. I also compute the 2-adic slopes of some automorphic forms with level structure at 2, giving evidence for the local constancy of the slopes.

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In addition to the paper, the following electronic appendices are available to subscribers :
Appendix A : This appendix contains SAGE/PYTHON scripts for calculating automorphic forms for the definite unitary group in 3 variables attached to Q(sqrt(-7)), of full level G(Z-hat).
Appendix B : This appendix contains programs to compute the slopes of the Up operator acting on forms of weight L, where L is the subgroup of elements of GL3(Zp) with first column (*, 0, 0)T mod 2.

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