TY - JOUR
T1 - Extremal metrics for spectral functions of Dirac operators in even and odd dimensions
AU - Møller, Niels Martin
PY - 2012/1/30
Y1 - 2012/1/30
N2 - Let (Mn, g) be a closed smooth Riemannian spin manifold and denote by ∇ its Atiyah-Singer-Dirac operator. We study the variation of Riemannian metrics for the zeta function and functional determinant of ∇2, and prove finiteness of the Morse index at stationary metrics, and local extremality at such metrics under general, i.e. not only conformal, change of metrics.In even dimensions, which is also a new case for the conformal Laplacian, the relevant stability operator is of log-polyhomogeneous pseudodifferential type, and we prove new results of independent interest, on the spectrum for such operators. We use this to prove local extremality under variation of the Riemannian metric, which in the important example when (Mn, g) is the round n-sphere, gives a partial verification of Branson's conjecture on the pattern of extremals. Thus det∇2 has a local (max, max, min, min) when the dimension is (4k, 4k+1, 4k+2, 4k+3), respectively.
AB - Let (Mn, g) be a closed smooth Riemannian spin manifold and denote by ∇ its Atiyah-Singer-Dirac operator. We study the variation of Riemannian metrics for the zeta function and functional determinant of ∇2, and prove finiteness of the Morse index at stationary metrics, and local extremality at such metrics under general, i.e. not only conformal, change of metrics.In even dimensions, which is also a new case for the conformal Laplacian, the relevant stability operator is of log-polyhomogeneous pseudodifferential type, and we prove new results of independent interest, on the spectrum for such operators. We use this to prove local extremality under variation of the Riemannian metric, which in the important example when (Mn, g) is the round n-sphere, gives a partial verification of Branson's conjecture on the pattern of extremals. Thus det∇2 has a local (max, max, min, min) when the dimension is (4k, 4k+1, 4k+2, 4k+3), respectively.
M3 - Journal article
SN - 0001-8708
VL - 229
JO - Advances in Mathematics
JF - Advances in Mathematics
ER -