We study the magnetic moments and transition magnetic moments of $P_c$ and $P_{cs}$ states in the molecular picture. We first revisit the magnetic moments of $P_c$ states as the $S$ wave molecular states without coupled channel effects. The coupled c
hannel effects and the $D$ wave contributions are then investigated carefully. The coupled channel effects contribute to the change of $0.1sim 0.4$ nuclear magneton $mu_N$ for most cases while the $D$ wave only induces the variation of less than $0.03 ~mu_N$. In addition, we obtain the transition magnetic moments between different $P_c$ states and the related electromagnetic decay widths of $P_cto P_cgamma$. The magnetic moments of $P_{cs}$ are much different for the assumption of spin being 1/2 and 3/2. The study of electromagnetic properties will help us disclose further the structure of these unconventional states.
In this work, we carry out the study of heavy flavor pentatuarks with four heavy quarks, which have typical $QQQQbar q$ configuration. Within the Chromomagnetic Interaction model, the mass spectrum of these discussed $QQQQbar q$ pentaquarks is given.
In addition to the mass spectrum analysis, we also illustrate their two-body strong decay behavior by estimating some ratios of decay channels. By these effort, we suggest that future experiment should pay attention to this kind of pentaquark.
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 $J/psiphi$ among all allowed hidden-charmed decays of $X(4630)$, 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.
Very recently, the LHCb Collaboration reported a fully charmed tetraquark state $X(6900)$ in the invariant mass spectrum of $J/psi$ pairs. If one $J/psi$ meson is replaced with a fully charmed baryon, we obtain a fully charmed pentaquark candidate. I
n this work, we perform a systematic study on the mass spectra of the S-wave fully heavy pentaquark $QQQQbar{Q}$ in the framework of the chromomagnetic interaction model. Based on our results in two different schemes, we further investigate the decay behaviors for them. We hope that our study will be helpful in searching for such types of exotic pentaquark states in experiments in the future.
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 $K^- d$ syste
m, taking careful account of the effects of recoil on the energy at which the $bar{K}N$ 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 $bar{K}N$ energy, which enhances the role of the $Lambda(1405)$ resonance.
We have studied the interactions between two heavy mesons ($D^{(*)}$-$D^{(*)}$, $bar D^{(*)}$-$bar D^{(*)}$, $B^{(*)}$-$B^{(*)}$, or $bar B^{(*)}$-$bar B^{(*)}$) within heavy meson chiral effective field theory and investigated possible molecular sta
tes. The effective potentials are obtained with Weinbergs scheme up to one-loop level. At the leading order, four body contact interactions and one pion exchange contributions are considered. In addition to two pion exchange diagrams, we include the one-loop chiral corrections to contact terms and one pion exchange diagrams at the next-to-leading order. The effective potentials both in momentum space and coordinate space are investigated and discussed extensively. The possible molecular states are also studied and the binding energies are provided by solving the Schrodinger equation. The results will be helpful for the experimental search for the doubly-heavy molecular states.
For the long standing low mass puzzle of $Lambda_c(2940)^+$, we propose an unquenched picture. Our calculation explicitly shows that the mass of the $Lambda_c(2P,3/2^-)$ state can be lowered down to be consistent with the experimental data of $Lambda
_c(2940)^+$ by introducing the $D^*N$ channel contribution. Additionally, we give a semi-quantitative analysis to illustrate why the $Lambda_c(2940)^+$ state has a narrow width. It means that the low mass puzzle of $Lambda_c(2940)^+$ can be solved. What is more important is that we predict a mass inversion relation for the $2P$ $Lambda_{c}^+$ states, i.e., the $Lambda_c(2P,1/2^-)$ state is higher than the $Lambda_c(2P,3/2^-)$, which is totally different from the result of conventional quenched quark model. It provides a criterion to test such an unquenched scenario for $Lambda_c(2940)^+$. We expect the future experimental progress from the LHCb and Belle II.
In the framework of the color-magnetic interaction model, we have systematically calculated the mass splittings for the S-wave triply heavy pentaquark states with the configuration $qqQQbar{Q}$ $(Q=c,b;q=u,d,s)$. Their masses are estimated and their
stabilities are discussed according to possible rearrangement decay patterns. Our results indicate that there may exist several stable or narrow such states. We hope the present study can help experimentalists to search for exotic pentaquarks.
Inspired by the observations of three $P_c$ states, we systematically investigate interactions between an $S$-wave charmed baryon $mathcal{B}_{c}^{(*)}=Lambda_c/Sigma_c/Sigma_c^{*}$ and an anticharmed meson $bar T=bar D_1/bar D_2^*$ with the one-pion
-exchange potential model and the one-boson-exchange potential model, and search for possible new types of $P_c$ states with the structures of $mathcal{B}_{c}^{(*)}bar T$. Both $S$-$D$ wave mixing and coupled channel effects are considered. Our results suggest that in some $mathcal{B}_{c}^{(*)}bar T$ systems there are ideal candidates of new types of $P_c$ states, i.e., the $Sigma_cbar{D}_1$ state with $I(J^P)=1/2(1/2^+)$, the $Sigma_cbar{D}_2^*$ state with $I(J^P)=1/2(3/2^+)$, the $Sigma_c^*bar{D}_1$ state with $I(J^P)=1/2(1/2^+)$, and the $Sigma_c^*bar{D}_2^*$ states with $I(J^P)=1/2(1/2^+, 3/2^+)$, and we suggest that these predicted new types of $P_c$ states can be detected in the process $Lambda_b^0 to psi(2S) p pi^{-}$. Meanwhile, we also extend our study to the interactions between an $S$-wave charmed baryon and a charmed meson in a $T$ doublet, and we predict a series of double-charm molecular pentaquarks.
The unflavored light meson families, namely $omega_2$, $rho_2$, and $phi_2$, are studied systematically by investigating the spectrum and the two-body strong decays allowed by Okubo-Zweig-Iizuka rule. Including the four experimentally observed states
and other predicted states, phenomenological analysis of the partial decay widths can verify the corresponding assignments of these states into the families. Moreover, we provide typical branching ratios of the dominant decay channels, especially for missing ground states, which is helpful to search for or confirm them and explore more properties of these families at experiment.
