Narrow Results

We combine the Bethe–Salpeter method with the ³P₀ model to describe OZI-allowed two body meson decays. In this combined method, the relativistic wave functions defined in the Salpeter equation show up in the decay amplitude of the ³P₀ model automatically. We apply the method to OZI-allowed ϒ(4S, 5S, 6S) two body decays. The results are roughly consistent with the experimental data and the predictions of ϒ(6S) decays are given.

New resonance X(3915) was identified as the charmonium χ_c0(2P) by BaBar Collaboration, but there still seems an open question of this assignment: why its full width is so narrow? To answer this question, we calculate the Okubo–Zweig–Iizuka (OZI)-allowed strong decays , where X(3915) is assigned as a χ_c0(2P) state, and estimate its full width in the cooperating framework of ³P₀ model and the Bethe–Salpeter (BS) method using the Mandelstam formalism, during which nonperturbative quantum chromodynamics (QCD) effects of the hadronic matrix elements are well-considered by overlapping integral over the relativistic Salpeter wave functions of the initial and final states. We find the node structure of χ_c0(2P) wave function resulting in the narrow width of X(3915) and show the dependence of the decay width on the variation of the initial mass of X(3915). We point out that the rate of is crucial to confirm whether X(3915) is the χ_c0(2P) state or not.

In this paper, we survey the radial and orbital excitations of I = 0 and systems anticipated up to 2.0 GeV in the framework of the chiral quark model. The Schrödinger equation is solved by using Gaussian expansion method. And using the wave functions obtained, instead of the simple harmonic oscillator wave functions, we study systematically the two-body strong decay (limited to S + S modes) of the systems. By comparing with the experimental data, we try to identify the normal states and exotic states.

In this paper, we assign the newly reported state $X(3842)$ to be a $D$-wave $\bar{c}c$ meson, and study its mass and decay constant with QCD sum rules by considering the contributions of vacuum condensates up to dimension-6 in the operator product expansion. The predicted mass $M_{X(3842)}=\left(\right.3.844_{-0.0823}^{+0.0675}\pm 0.020\left)\right.$ GeV is in agreement with the experimental data $M_{X(3842)}=(3842.71\pm 0.16\pm 0.12)$ MeV from the LHCb collaboration. This result supports assigning $X(3842)$ as the $1^3{D}_3$ charmonium meson. In this case, its predicted strong decay width with the ${}^3{P}_0$ decay model is compatible with the experimental data.

Recently, LHCb collaboration has confirmed the state X(4140), with a much larger width $\text{Γ}=83\pm {21}_{-14}^{+21}$ MeV than the previous experimental measurements, which has confused the understanding of its nature. We have investigated the possibility of the χ_c1(3P) interpretation for the X(4140), considering the mass and the strong decay properties.