Transverse lattice-point counting conjecture for spherical bands

Let Ak,d,λA_{k,d,\lambda} denote the maximal number of lattice points in the intersection of kk unit-width, ν\nu-transverse bands on the sphere λSd1\lambda S^{d-1}, with 1kd11\le k\le d-1. Spherical-band counting conjecture. For d2d\ge2 and 1kd11\le k\le d-1,

Ak,d,λ1,when dk=1,A_{k,d,\lambda}\lesssim1,\qquad\text{when }d-k=1,

and

Ak,d,λελdk2+ε,ε>0,when dk2.A_{k,d,\lambda}\lesssim_\varepsilon \lambda^{d-k-2+\varepsilon},\qquad\forall\varepsilon>0,\quad\text{when }d-k\ge2.

The paper proves lower bounds of the expected order in the relevant ranges, but the corresponding upper bounds are presented as conjectural.

Sources & referencesView supporting material

Primary source

Cheng Zhang and Zhifei Zhu, “Restriction estimates for toral eigenfunctions and lattice points in spherical regions”, arXiv:2606.08650 (2026).

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