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Improved XTZ masses and mass ratios from Laplace Sum Rules at NLO

Published 31 Jan 2022 in hep-ph, hep-ex, and hep-lat | (2201.13449v3)

Abstract: We present improved estimates of the couplings, masses and mass ratios of the Z_Q,X_Q and T_{QQqq} states using QCD Laplace sum rules (LSR), their ratios R 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 MS heavy quark mass used in the analysis. We show that combined R and DRSR can provide more precise results. First, we conclude that the observed X_c(3872) and Z_c(3900) are tetramoles states (superposition of quasi-degenerated molecule and a tetraquark states having (almost) the same coupling to the currents) with the predicted masses: M_{T_{X_c}}=3876(44) MeV and M_{ T_{Z_c}}=3900(42) MeV. In the 2nd part, we focus on the analysis of the four-quark nature of different T_{QQqq'} 1+ and 0+ states within the 3_c3_c interpolating currents. The final results are summarized in Table 7. Combined R and DRSR calibrated to the observed X_c(3872) lead to a precise prediction of e.g. M_{T_{cc}{1+}}=3886(6) MeV. In a similar way, the DRSR for M_{T_{cc}{0+}}/M_{T_{cc}{1+}} calibrated to M_{T_{cc}{1+}} gives M_{T_{cc}{0+}}= 3883(3) MeV. The SU3 breaking ratios M_{T_{ccss}{0+}}/ M_{T_{cc}{0+}} lead to the improved mass predictions: M_{T_{ccss}{0+}}=3988(12) MeV. In the 3rd part, the analysis is extended to the beauty mesons, where we find the tetramole masses : M_{ T_{Z_b}}=10579(99) MeV and M_{X_b}=10545(131) MeV. We also observe that the T{1+,0+}_{bbqq'} 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 T{1+,0+}_{QQqq'} masses. Our results from LSR+DRSR are confronted with the ones from some other approaches (lattices and quark models) in Fig. 25.

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