We show that despite the absence of a spectral gap for all #92;alpha#92;in(0,1) and despite nonsummable correlations for #92;alpha#92;geq 1#47;2, the map #92;alpha#92;mapsto#92;int#92;varphi#92;,d#92;nu#95;#92;alpha is continuously differentiable for #92;varphi#92;inL#123;q#125;#91;0,1#93; for q sufficiently large..
Source: wiktionary