The conjectural double Fourier–Mellin transform formula over the complex numbers

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Let pp be an integer, let β,γ,ν∈C\beta,\gamma,\nu\in\mathbb{C}, and let u,\varw∈Cu,\varw\in\mathbb{C} satisfy

Re⁡(1/(u\varw))<1.\operatorname{Re}(1/(u\varw))<1.

For the Bessel function Bν,p\boldsymbol{B}_{\nu,p} and the associated function Hν,pβ−γ\boldsymbol{H}_{\nu,p}^{\beta-\gamma}, the double Fourier–Mellin transform conjecture. The integral formula

∫ ⁣ ⁣∫ ⁣ ⁣∫ ⁣ ⁣∫Bν,p(\varvz)e(−2Re⁡(uz+\varw\varv))i dz∧d\widebarz∣z∣2−2βi d\varv∧d\widebar\varv∣\varv∣2−2γ=2(2π)2β+2γ∣u∣2β∣\varw∣2γ β+γ ⁣Hν,pβ−γ ⁣(1u\varw)\begin{aligned} &\int\!\!\int\!\!\int\!\!\int \boldsymbol{B}_{\nu,p}(\sqrt{\varv z})e\bigl(-2\operatorname{Re}(uz+\varw\varv)\bigr)\frac{i\,dz\wedge d\widebar{z}}{|z|^{2-2\beta}}\frac{i\,d\varv\wedge d\widebar{\varv}}{|\varv|^{2-2\gamma}} \\ &\qquad=\frac{2}{(2\pi)^{2\beta+2\gamma}|u|^{2\beta}|\varw|^{2\gamma}}\,{}^{\beta+\gamma}\!\boldsymbol{H}_{\nu,p}^{\beta-\gamma}\!\left(\frac{1}{u\varw}\right) \end{aligned}

is valid whenever

∣Re⁡(ν)∣<Re⁡(2β)<32,∣Re⁡(ν)∣<Re⁡(2γ)<min⁡{1+Re⁡(2β),3−Re⁡(2β)}.|\operatorname{Re}(\nu)|<\operatorname{Re}(2\beta)<\frac{3}{2},\qquad |\operatorname{Re}(\nu)|<\operatorname{Re}(2\gamma)<\min\bigl\{1+\operatorname{Re}(2\beta),3-\operatorname{Re}(2\beta)\bigr\}.

This conjecture extends the preceding complex double Fourier–Mellin identity from even pp to arbitrary pp and general Mellin exponents. Its validity is motivated by the corresponding real-variable formulas, but the supplied text gives no proof or resolution.

References

Primary source

Zhi Qi, “On the Hankel Transform of Bessel Functions on Complex Numbers and Explicit Spectral Formulae over the Gaussian Field”, arXiv:2310.19480 (2024).

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