Lifespan of semilinear wave equation with scale invariant dissipation and mass and sub-Strauss power nonlinearity

In this paper, we study the blow-up of solutions for semilinear wave equations with scale-invariant dissipation and mass in the case in which the model is somehow “wave-like”. A Strauss type critical exponent is determined as the upper bound for the exponent in the nonlinearity in the main theorems. Two blow-up results are obtained for the subcritical case and for the critical case, respectively. In both cases, an upper bound lifespan estimate is given.