XYZ from QCD Laplace sum rules

In this paper, we present a review of our recent works on heavy-light molecule and tetraquark states. New compact integrated expressions of the spectral functions at lowest order (LO) of perturbative (PT) QCD and up to dimension [Formula: see text] condensates of the Operator Product Expansion (OPE) are used. Including higher-order (HO) PT corrections which we have estimated by assuming the factorization of the molecule/four-quark spectral functions, we evaluate masses and couplings with the Laplace sum rules (LSR). Our optimal results based on stability criteria are summarized in Tables 4 to 6 and compared with experimental candidates and some LO QCD spectral sum rules (QSSR) results. We conclude that the masses of the observed [Formula: see text] states are compatible with (almost) pure [Formula: see text] molecule or/and four-quark states. The SU(3) corrections on the meson masses are tiny: [Formula: see text] (respectively [Formula: see text]) for the c (respectively b)-quark channel but can be large for the couplings ([Formula: see text]).