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Is Z b (10610) a molecular state?

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Abstract

Whether molecular states indeed exist in nature has been disputed for a long time. Several new resonances have been observed in the recent experiments and they seem to be of exotic structures and some of them have been proposed to be molecular states. The very recent observation of Z b (10610)[(10608.4 ± 2.0) MeV] and Z b (10650)[(10653.2 ± 1.5) MeV] encourages the interpretation of multi-quark states. In the Beter-Salpeter (BS) approach, we study the possibility if two heavy mesons can form a molecular state by exchanging light mesons. Our results indicate that two heavy mesons can form an isospin singlet (I = 0) bound state but cannot form an isospin triplet (I = 1) when the contribution of σ- exchange is reasonably small, i.e. as the coupling of σ with mesons gσ takes the value given in previous literatures. Thus we conclude that the newly observed Z b (10610) should not be a molecular state, but a tetraquark state instead, at most, the fraction of the molecular state in the physical resonance Z b (10610) is tiny.

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Authors and Affiliations

  1. School of Science, Tian** University, Tian**, 300072, China

    Hong-Wei Ke

  2. School of Physics, Nankai University, Tian**, 300071, China

    Xue-Qian Li & Yan-Liang Shi

  3. Department of Physics, Harbin Institute of Technology, Harbin, 150001, China

    Guo-Li Wang

  4. Center for High Energy Physics, Department of Engineering Physics, Tsinghua University, Bei**g, 100084, China

    Xu-Hao Yuan

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ArXiv ePrint: 1202.2178

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Ke, HW., Li, XQ., Shi, YL. et al. Is Z b (10610) a molecular state?. J. High Energ. Phys. 2012, 56 (2012). https://doi.org/10.1007/JHEP04(2012)056

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