0+ and 1+ heavy-light exotic mesons at N2LO in the chiral limit

TL;DR

This paper employs QCD spectral sum rules at N2LO to estimate masses and couplings of 0+ and 1+ heavy-light exotic mesons, improving upon previous leading-order results and aligning with observed XZ-like states.

Contribution

The study provides the first N2LO QCD sum rule estimates for heavy-light exotic mesons, including non-perturbative effects up to dimension-six, enhancing the accuracy of previous LO analyses.

Findings

Masses and couplings are consistent with observed XZ-like states.

Results show improved precision over previous LO calculations.

The approach confirms the molecule and four-quark nature of these states.

Abstract

We use QCD spectral sum rules (QSSR) and the factorization properties of molecule and four-quark currents to estimate the masses and couplings of the 0+ and 1+ molecules and four-quark at N2LO of PT QCD. We include in the OPE the contributions of non-perturbative condensates up to dimension-six. Within the Laplace sum rules approach (LSR) and in the MS-scheme, we summarize our results in Table 2, which agree within the errors with some of the observed XZ-like molecules or/and four-quark. Couplings of these states to the currents are also extracted. Our results are improvements of the LO ones in the existing literature.