Final published version
Research output: Contribution to Journal/Magazine › Journal article › peer-review
Research output: Contribution to Journal/Magazine › Journal article › peer-review
}
TY - JOUR
T1 - Group ring elements with large spectral density
AU - Grabowski, Łukasz
PY - 2015/10/1
Y1 - 2015/10/1
N2 - Given δ>0δ>0 we construct a group GG and a group ring element S∈Z[G]S∈Z[G] such that the spectral measure μμ of SS fulfils μ((0,ε))>C|log(ε)|1+δμ((0,ε))>C|log(ε)|1+δ for small εε. In particular the Novikov-Shubin invariant of any such SS is 00. The constructed examples show that the best known upper bounds on μ((0,ε))μ((0,ε)) are not far from being optimal.
AB - Given δ>0δ>0 we construct a group GG and a group ring element S∈Z[G]S∈Z[G] such that the spectral measure μμ of SS fulfils μ((0,ε))>C|log(ε)|1+δμ((0,ε))>C|log(ε)|1+δ for small εε. In particular the Novikov-Shubin invariant of any such SS is 00. The constructed examples show that the best known upper bounds on μ((0,ε))μ((0,ε)) are not far from being optimal.
KW - 20C07
KW - 20F65
KW - 57M10
U2 - 10.1007/s00208-015-1170-7
DO - 10.1007/s00208-015-1170-7
M3 - Journal article
VL - 363
SP - 637
EP - 656
JO - Mathematische Annalen
JF - Mathematische Annalen
SN - 0025-5831
IS - 1
ER -