Narrow Results

The hybrid meson is one of the most interesting new hadron species beyond the naive quark model. It acquire great attention both from the theoretical and experimental efforts. Many good candidates have been claimed to be observed, but there is no absolute confirmation about the existence of hybrid mesons. In the present work we propose new calculations of the masses and decay widths of the hybrid mesons in the context of constituent gluon model.

We present new results concerning the masses and the decay widths of the most interesting hybrid meson states taking as inputs the gluon mass m_g and the nonperturbative QCD running coupling constant α_s(0) coming from both LQCD and SDE recent estimations.

Motivated by recent progresses in experiments in searching for the ${\mathrm{\Omega }}_c$ baryons, we systematically analyze the strong decay behaviors of single heavy baryons ${\mathrm{\Lambda }}_Q$, ${\mathrm{\Sigma }}_Q$ and ${\mathrm{\Omega }}_Q$. The two-body strong decay properties of $S$-wave, $P$-wave and some $D$-wave states are studied with the ${}^3{P}_0$ model. The results support assigning the recently observed ${\mathrm{\Omega }}_c(3185)$ and ${\mathrm{\Omega }}_c(3327)$ as the 2S(${\frac{3}{2}}^{+}$) and 1D(${\frac{3}{2}}^{+}$) states, respectively. In addition, the quantum numbers of many other experimentally observed baryons are also suggested according to their strong decays. Finally, some baryons which have good potentials to be observed in experiments are predicted and the possible decay channels for searching for these predicted states are also suggested.

In this study, we analyze the strong decays of singly charmed baryons into another singly charmed baryon and a light pseudo scalar meson by means of Heavy Hadron Chiral Perturbation Theory (HHChPT) which combines heavy quark symmetry with chiral symmetry. HHChPT worked excellently for describing the strong decays of $1S$-wave charmed baryons. The strong decay widths of well-established singly charmed baryons are well reproduced. Further, the strong decay width of $1P$ states is calculated in this approach by using the calculated masses in the Relativistic Flux Tube (RFT) model. By analyzing the mass spectra from the RFT model with strong decays in HHChPT, we investigate the spin-parity assignments. We identify ${\mathrm{\Sigma }}_c(2800)$ and ${\mathrm{\Xi }}_c(2939)$ as $1P$-wave states having $J^P={\frac{3}{2}}^{-}$.

In this work, we calculate the mass spectrum of the bottom mesons with a modified nonrelativistic quark model by involving the screening effect, and explore their strong decay properties within the ³P₀ model. Our results suggest that the $B_1(5721)$, $B_2^{\ast }(5747)$, $B_J(5840)$ and $B_J(5970)$ could be reasonably assigned as the $B_1^{\prime }(1P)$, $B(1^3{P}_2)$, $B(2^1{S}_0)$ and $B(1^3{D}_3)$, respectively. The more precise measurements of the excited bottom mesons are crucial to confirm these assignments.

Partial decay widths of the heavy-light mesons, D, D_s, B, and B_s, emitting one chiral particle (π or K) or photon γ are evaluated in the framework of a relativistic potential model. Decay amplitudes are calculated by keeping the Lorentz invariance as far as possible and use has been made of the Lorentz-boosted relativistic wave functions of the heavy-light mesons. One of predictions of our calculation is very narrow widths of a few keV for yet undiscovered B_s(0⁺, 1⁺) mesons corresponding to ^2S+1L_J = ³P₀ and "³P₁" assuming their masses to be 5617 and 5682 MeV, respectively, as calculated in our former paper.

Sizable radiative decay widths of D* or are obtained by including the 1st order corrections in 1/m_Q expansion, in the unit of keV; Γ(D^*0 → D⁰ + γ) = 9.8, Γ (D^*+ → D⁺ + γ) = 0.71, and large radiative decay widths of D_sJ are obtained compared with non-relativistic results.

In this work we have obtained an effective Hamiltonian to describe the strong decay of pseudoscalar glueball, where the microscopic interaction between the constituent gluons have been taking into account. The pseudoscalar glueball candidate we have considered here is the $X(1835)$ resonance. In our calculation the $X(1835)$ was a pure glueball.

The first two pentaquark candidates P_c(4380) and P_c(4450) were observed by LHCb Collaboration in 2015. Recently, they presented their improved measurements in the P_c energy range, that a new narrow signal denoted as P_c(4312) is reported and the previous observed structure P_c(4450) is resolved into two narrow states, P_c(4440) and P_c(4457) while there is no obvious signal for the broad state P_c(4380). We analyze the strong decays of these P_c states systematically in the hadronic molecule pictures. With the effective Lagrangian method, the partial widths of these P_c decaying into all allowed channels are estimated. Our results show that these P_c states are good candidates of the S-wave $\overline{D}{\mathrm{\Sigma }}_c,\overline{D}{\mathrm{\Sigma }}_c^{*}$ and $\overline{D}*{\mathrm{\Sigma }}_c$ molecules. Also other possible flavor and spin partners of P_c states are investigated in the present work.

To understand the nature of the low-lying negative parity Λ resonances, we carried out a combined study of the reaction K⁻p → Λη at low energies and their strong decays with a chiral quark model. It is found that the low-lying negative parity Λ resonances, such as Λ(1670), Λ(1405), Λ(1520) and Λ(1690), are most likely mixed states between different configurations.