Improved XTZ masses and mass ratios from Laplace sum rules at NLO
Résumé
We present improved estimates of the couplings, masses and mass ratios of the and states () using (inverse) QCD Laplace sum rules (LSR), their ratios and double ratios DRSR within stability criteria, where the NLO factorized PT QCD corrections are included which is important for giving a meaning on the running heavy quark mass used in the analysis. We show that combined and DRSR can provide more precise results. In the 1st part of the paper, we conclude that the observed and are tetramoles states (superposition of quasi-degenerated molecule and a tetraquark states having (almost) the same coupling to the currents) with the predicted masses: and . In the 2nd part, we focus on the analysis of the four-quark nature of different and states within the interpolating currents. The final results from and DRSR are summarized in Table 7. Combined and DRSR calibrated to the observed lead to a precise prediction of e.g. . In a similar way, the DRSR for the calibrated to gives . The SU3 breaking ratios lead to the improved mass predictions: . In the 3rd part, the analysis is extended to the beauty mesons, where we find the tetramole masses: and . We also observe that the () states are (almost) stable (within the errors) against strong interactions. In the 4th part, we (critically) review and correct some recent LSR estimates of the masses. Our combined LSR ⊕ DRSR results are confronted with the ones from some other approaches (lattices and quark models) in Fig. 26.
Mots clés
QCD spectral sum rules
Perturbative and non-perturbative QCD
Exotic hadrons
Masses and decay constants
hadron spectroscopy
hadron: exotic
sum rule: Laplace
quantum chromodynamics: correction
heavy quark: mass
stability
mass ratio
bottom meson
strong interaction
tetraquark
hadron: molecule
X(3872)
Z/c(3900)
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