On the equivalent Zb\v{a}ganu constant associated with isosceles orthogonality in Banach spaces

Abstract

This paper systematically investigates a new geometric constant associated with isosceles orthogonality in Banach spaces. By establishing the connection between this new constant and a classical function, sharp upper and lower bounds for the constant are derived. Specifically, the space is exactly a Hilbert space when the new constant reaches its lower bound; in finite-dimensional spaces, if the new constant attains its upper bound, it implies that the space does not possess uniform non-squareness.