Search

Abstract Stimulated by the observation of the X(6900) from LHCb in 2020 and the recent results from CMS and ATLAS in the di- $$J/\psi $$ J / ψ invariant mass spectrum, in this work we systematically study all possible configurations for the ground states of fully heavy tetraquark in the constituent quark model. By our calculation, we present their spectroscopic behaviors including binding energy, lowest meson–meson thresholds, specific wave function, magnetic moment, transition magnetic moment, radiative decay width, rearrangement strong width ratio, internal mass contributions, relative lengths between (anti)quarks, and the spatial distribution of four valence (anti)quarks. We cannot find a stable S-wave state for the fully heavy tetraquark system. We hope that our results will be valuable to further experimental exploration of fully heavy tetraquark states.

Abstract Very recently, the LHCb Collaboration at the Large Hadron Collider at CERN observed new resonance X(4630). The X(4630) is decoded as a charmoniumlike molecule with hidden-strange quantum number well in the one-boson-exchange mechanism. Especially, the study of its hidden-charmed decays explicitly shows the dominant role of $$J/\psi \phi $$ J / ψ ϕ among all allowed hidden-charmed decays of the X(4630), which enforces the conclusion of X(4630) as a charmoniumlike molecule. The discovery of the X(4630) is a crucial step of constructing charmoniumlike molecule zoo.

Abstract For the long standing low mass puzzle of $$\Lambda _c(2940)^+$$ Λc(2940)+ , we propose an unquenched picture. Our calculation explicitly shows that the mass of the $$\Lambda _c(2P,3/2^-)$$ Λc(2P,3/2-) state can be lowered down to be consistent with the experimental data of $$\Lambda _c(2940)^+$$ Λc(2940)+ by introducing the $$D^*N$$ D∗N channel contribution. It means that the low mass puzzle of $$\Lambda _c(2940)^+$$ Λc(2940)+ can be solved. What is more important is that we predict a mass inversion relation for the 2P $$\Lambda _{c}^+$$ Λc+ states, i.e., the $$\Lambda _c(2P,1/2^-)$$ Λc(2P,1/2-) state is higher than the $$\Lambda _c(2P,3/2^-)$$ Λc(2P,3/2-) , which is totally different from the result of conventional quenched quark model. It provides a criterion to test such an unquenched scenario for $$\Lambda _c(2940)^+$$ Λc(2940)+ . We expect the future experimental progress from the LHCb and Belle II.

The anti-kaon nucleon scattering lengths resulting from a Hamiltonian effective field theory analysis of experimental data and lattice QCD studies are presented. The same Hamiltonian is then used to compute the scattering length for the K−d system, taking careful account of the effects of recoil on the energy at which the K¯N T-matrices are evaluated. These results are then used to estimate the shift and width of the 1S levels of anti-kaonic hydrogen and deuterium. The K−p result is in excellent agreement with the SIDDHARTA measurement. In the K−d case the imaginary part of the scattering length and consequently the width of the 1S state are considerably larger than found in earlier work. This is a consequence of the effect of recoil on the energy of the K¯N energy, which enhances the role of the Λ(1405) resonance.

Abstract We have systematically investigated the decuplet (T) to octet (B) baryon ($$T\rightarrow B\gamma $$ T→Bγ ) transition magnetic moments to the next-to-next-to-leading order and electric quadruple moments to the next-to-leading order in the framework of the heavy baryon chiral perturbation theory. Our calculation includes the contributions from both the intermediate decuplet and octet baryon states in the loops. Throughout our calculation, we have adopted the small-scale scheme and have not considered the 1/M recoiling corrections directly. We count the octet and decuplet baryon mass splitting $$\delta $$ δ , the small momenta p, and the pion mass $$m_{\phi }$$ mϕ as the same order small-scale parameter, which was denoted as $$\epsilon $$ ϵ . Our results for the transition magnetic moments show reasonably good convergence of the chiral expansion. The analytical expressions may be useful to the chiral extrapolation of the lattice simulations of the decuplet electromagnetic properties.

We have systematically investigated the spin-32 to spin-12 doubly charmed baryon transition magnetic moments to the next-to-next-to-leading order in the heavy baryon chiral perturbation theory (HBChPT). Numerical results of transition magnetic moments and decay widths are presented to the next-to-leading order: μΞcc⁎++→Ξcc++=−2.35μN, μΞcc⁎+→Ξcc+=1.55μN, μΩcc⁎+→Ωcc+=1.54μN, ΓΞcc⁎++→Ξcc++=22.0 keV, ΓΞcc⁎+→Ξcc+=9.57 keV, ΓΩcc⁎+→Ωcc+=9.45 keV.

Abstract In this work, we investigate the chiral corrections to the magnetic moments of the spin- $$3\over 2$$ 3 2 doubly charmed baryons systematically up to next-to-next-to-leading order with the heavy baryon chiral perturbation theory. The numerical results are given up to next-to-leading order: $$\mu _{\varXi ^{*++}_{cc}}=2.61\mu _{N}$$ μ Ξ cc ∗ + + = 2.61 μ N , $$\mu _{\varXi ^{*+}_{cc}}=-0.18\mu _{N}$$ μ Ξ cc ∗ + = - 0.18 μ N , $$\mu _{\varOmega ^{*+}_{cc}}=0.17\mu _{N}$$ μ Ω cc ∗ + = 0.17 μ N . As a by-product, we have also calculated the magnetic moments of the spin- $$3\over 2$$ 3 2 doubly bottom baryons and charmed bottom baryons: $$\mu _{\varXi ^{*0}_{bb}}=2.83\mu _{N}$$ μ Ξ bb ∗ 0 = 2.83 μ N , $$\mu _{\varXi ^{*-}_{bb}}=-1.33\mu _{N}$$ μ Ξ bb ∗ - = - 1.33 μ N , $$\mu _{\varOmega ^{*-}_{bb}}=-1.54\mu _{N}$$ μ Ω bb ∗ - = - 1.54 μ N , $$\mu _{\varXi ^{*+}_{bc}}=3.22\mu _{N}$$ μ Ξ bc ∗ + = 3.22 μ N , $$\mu _{\varXi ^{*0}_{bc}}=-0.84\mu _{N}$$ μ Ξ bc ∗ 0 = - 0.84 μ N , $$\mu _{\varOmega ^{*0}_{bc}}=-1.09\mu _{N}$$ μ Ω bc ∗ 0 = - 1.09 μ N .