Sharp dependence on the interpolation parameter

Determine whether the stability estimate O_{n,\lambda,p}(\sqrt{\delta}) for the Borell–Brascamp–Lieb inequality can be replaced by the sharper bound O_{n,p}(\sqrt{\delta/\lambda}), thereby establishing the conjectured dependence on the parameter \lambda.

Background

The paper proves quantitative stability for the Borell–Brascamp–Lieb inequality with an error term of order O_{n,\lambda,p}(\sqrt{\delta}), where \delta measures the deficit and \lambda is the interpolation parameter. The authors note that corresponding sharp stability results for the Brunn–Minkowski inequality suggest the more precise dependence O_{n,p}(\sqrt{\delta/\lambda}).

Establishing this improvement would require additional nontrivial arguments beyond those developed in the paper, so the sharper dependence remains unresolved and is explicitly left for future work. The problem is included because it concerns the optimal quantitative dependence of the stability estimate on a fundamental parameter of the inequality.

References

Regarding the dependence on \lambda, based on corresponding results for the Brunn-Minkowski inequality (see, in particular, ), it is natural to expect that the expression O_{n,\lambda,p}(\sqrt{\delta}) can be replaced by O_{n,p}(\sqrt{\delta/\lambda}). However, proving this bound would require nontrivial work beyond the scope of the current paper, which already introduces several intricate tools and ideas. Therefore, we leave this investigation for future work.

Sharp Quantitative Stability for the Prékopa-Leindler and Borell-Brascamp-Lieb Inequalities  (2501.04656 - Figalli et al., 8 Jan 2025) in Remark following Theorem 1.1 in Section 1, subsection “Main results”