Zeros of Rankin–Selberg L-functions in families

Let Fₙ be the set of all cuspidal automorphic representations of GLₙ with unitary central character over a number field F. We prove the first unconditional zero density estimate for the set S=\L (s, ') {Fₙ\} of Rankin–Selberg L -functions, where ' F₍' is fixed. We use this density estimate to establish: (i) a hybrid-aspect subconvexity bound at s= 12 for almost all L (s, ') S ; (ii) a strong on-average form of effective multiplicity one for almost all Fₙ ; and (iii) a positive level of distribution for L (s, ), in the sense of Bombieri–Vinogradov, for each Fₙ.