Simple \(3\)-designs of \(\text{PSL}(2,q)\) with Block Size \(7\)

Abstract

This paper devotes to the investigation of \(3\)-designs admitting the special projective linear group \(\text{PSL}(2,q)\) as an automorphism group. When \(q \equiv 3 \pmod{4}\), we determine all the possible values of \(\lambda\) in the simple \(3\)-\((q+1, 7, \lambda)\) designs admitting \(\text{PSL}(2,q)\) as an automorphism group.