Constantes de acoplamento de vértices com mésons estranhos e charmosos usando as regras de soma da QCD

Abstract

In this work, the form factors and coupling constants of the meson vertices J/ψ DsDs, J/ψ Ds*Ds and J/ψ Ds*Ds* have been calculated with the QCD sum rule (QCDSR) technique up to dimension 5 of the operator product expansion (OPE). These three vertices are involved in some of the numerous hypotheses that attempt to explain the internal structure of some exotic charmed mesons which began to be observed since 2003. Such mesons do not fit in the charmonium spectrum and/or have exotic quantum numbers within the CQM (constituent quark model). An example is the Y(4140) meson, which decays in the pair J/ψφ while the expected would be a dominant decay in open charm mesons. One of the proposals to understand this meson is to study it as a molecular state Ds*{D}s*, so it would decay as Y(4140)→ Ds* {D}s* → J/ψφ.In this process, the vertices studied in this work will appear, so the more accurate knowledge of their form factors and their coupling constants can benefit our understanding of the fundamental constitution of the Y(4140) as well as other new states as the X(4350), Y(4274) and Y (4660) eg. In this study all possible off-shell cases for each of these three vertices were considered, thus obtaining two different form factors for the vertex J/ψ DsDs, three for the vertex J/ψ Ds*Ds and two for the vertex J/ψ Ds* Ds*. In these three vertices, the form factors for the J/ψ off-shell case were well fitted by monopolar curves, while the Ds and Ds* off-shell cases were well fitted by exponential curves which is in agreement with the behavior found in previous work of the group. The calculations of the coupling constants leaded to the following results: g_{J/ψ Ds Ds} = 5.98^{+0.67}_{-0.58}, g_{J/ψ Ds* Ds} = 4.30^{+0.41}_{-0.35}GeV^{-1} and g_{J/ψ Ds* Ds*} = 7.47^{+1.04}_{-0.71}, these results are compatible with previous QCDSR works for the non strange vertices J/ψD(*)D(*).