The global extreme-zero product conjecture for transitional Laguerre polynomials

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For n=0,1,…n=0,1,\dots and α>−1\alpha>-1, define the transitional Laguerre polynomials L^n+1(α)(⋅,t)\widehat{L}^{(\alpha)}_{n+1}(\cdot,t) by

L^n+1(α)(⋅,t)=(x−(2n+α+1))Ln(α)(x)−n(n+α)t2Ln−1(α)(x),\widehat{L}^{(\alpha)}_{n+1}(\cdot,t)=(x-(2n+\alpha+1))L^{(\alpha)}_n(x)-n(n+\alpha)t^2L^{(\alpha)}_{n-1}(x),

where

L−1(α)=0,L^n(α)=(−1)nn!Ln(α).L^{(\alpha)}_{-1}=0,\qquad \widehat{L}^{(\alpha)}_n=(-1)^n n!L^{(\alpha)}_n.

Let the extreme zeros denote the smallest and largest zeros of a polynomial. Global extreme-zero product conjecture. For all α>−1\alpha>-1, n=5,6,…n=5,6,\dots, and t∈(0,1]t\in(0,1], the product of the extreme zeros of L^n+1(α)(⋅,t)\widehat{L}^{(\alpha)}_{n+1}(\cdot,t) is greater than the product of the extreme zeros of L^n+1(α)(⋅,0)\widehat{L}^{(\alpha)}_{n+1}(\cdot,0).

This extends the proposition's partial result, which covers only −1<α≤47.9603-1<\alpha\leq47.9603 and t∈[0,0.568774]t\in[0,0.568774]. Numerical evidence includes the Hermite-related cases α=±1/2\alpha=\pm1/2 and t=1t=1, but the assertion for all admissible α\alpha, all n≥5n\geq5, and t∈(0,1]t\in(0,1] remains open.

References

Primary source

K. Castillo, “On the product of the extreme zeros of Laguerre polynomials”, arXiv:2409.09405 (2024).

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