No Arabic abstract
The mass spectrum of hidden charm pentaquark states composed of two diquarks and an antiquark are calculated by use of an effective Hamiltonian which includes explicitly the spin, color, and flavor dependent interactions. The results show that the $P_c(4312)^+$ and $P_c(4440)^+$ states could be explained as hidden charm pentaquark states with isospin and spin-parity $IJ^P=1/2left(3/2^-right)$, the $P_c(4457)^+$ state could be explained as a hidden charm pentaquark state with $IJ^P=1/2left(5/2^-right)$, and the $P_{cs}(4459)^+$ state could be explained as a hidden charm pentaquark state with $IJ^P=0left(1/2^-right)$ or $0left(3/2^-right)$. Predications for the masses of other possible pentaquark states are also given, and the possible decay channels of these hidden charm pentaquark states are discussed.
The purpose of the present study is to explore the mass spectrum of the hidden charm tetraquark states within a diquark model. Proposing that a tetraquark state is composed of a diquark and an antidiquark, the masses of all possible $[qc][bar{q}bar{c}]$, $[sc][bar{s}bar{c}]$, and $[qc][bar{s}bar{c}]$ $left([sc][bar{q}bar{c}]right)$ hidden charm tetraquark states are systematically calculated by use of an effective Hamiltonian, which contains color, spin, and flavor dependent interactions. Apart from the $X(3872)$, $Z(3900)$, $chi_{c2}(3930)$, and $X(4350)$ which are taken as input to fix the model parameters, the calculated results support that the $chi_{c0}(3860)$, $X(4020)$, $X(4050)$ are $[qc][bar{q}bar{c}]$ states with $I^GJ^{PC}=0^+0^{++}$, $1^+1^{+-}$, and $1^-2^{++}$, respectively, the $chi_{c1}(4274)$ is an $[sc][bar{s}bar{c}]$ state with $I^GJ^{PC}=0^+1^{++}$, the $X(3940)$ is a $[qc][bar{q}bar{c}]$ state with $I^GJ^{PC}=1^-0^{++}$ or $1^-1^{++}$, the $Z_{cs}(3985)^-$ is an $[sc][bar{q}bar{c}]$ state with $J^{P}=0^{+}$ or $1^+$, and the $Z_{cs}(4000)^+$ and $Z_{cs}(4220)^+$ are $[qc][bar{s}bar{c}]$ states with $J^{P}=1^{+}$. Predictions for other possible tetraquark states are also given.
In this work we study the formation of $N^*$s as a consequence of the dynamics involved in the $NDbar D^*-Nbar D D^*$ system when the $Dbar D^*-bar D D^*$ subsystem generates $X(3872)$ in isospin 0 and $Z_c(3900)$ in isospin 1. States with isospin $I=1/2$ and mass in the energy region $4400-4600$ MeV are obtained with spin-parity $J^P=1/2^+$ and $3/2^+$, predicting in this way the existence of $N^*$ resonances with hidden charm and a three-body nature.
$QQ^prime qqbar q$ pentaquarks are studied in a potential model, under the hypothesis that they are composite objects of two diquarks and one antiquark. The interaction between two colored objects includes two contributions, one based on the $qbar q$ potential in QCD, computed in the gauge/string duality approach, and another describing the spin-spin interaction. The model has been extended to investigate pentaquarks with different quark content, as $Qqqqbar q$ and $Qqqqbar Q$, the latter including the states observed by LHCb, $P_c(4380)^+$ and $P_c(4450)^+$, later updated, with a new data sample, to $P_c(4312)^+$, $P_c(4440)^+$, and $P_c(4457)^+$.
The observation by BESIII and LHCb of states with hidden charm and open strangeness ($cbar c qbar s$) presents new opportunities for the development of a global model of heavy-quark exotics. Here we extend the dynamical diquark model to encompass such states, using the same values of Hamiltonian parameters previously obtained from the nonstrange and hidden-strange sectors. The large mass splitting between $Z_{cs}(4000)$ and $Z_{cs}(4220)$ suggests substantial SU(3)$_{rm flavor}$ mixing between all $J^P ! = ! 1^+$ states, while their average mass compared to that of other sectors offers a direct probe of flavor octet-singlet mixing among exotics. We also explore the inclusion of $eta$-like exchanges within the states, and find their effects to be quite limited. In addition, using the same diquark-mass parameters, we find $P_c(4312)$ and $P_{cs}(4459)$ to fit well as corresponding nonstrange and open-strange pentaquarks.
We study the $P_{cs}(4459)^0$ recently observed by LHCb using the method of QCD sum rules. Our results support its interpretation as the $bar D^* Xi_c$ hadronic molecular state of either $J^P=1/2^-$ or $3/2^-$. Within the hadronic molecular picture, the three LHCb experiments observing $P_c$ and $P_{cs}$ states cite{lhcb,Aaij:2015tga,Aaij:2019vzc} can be well understood as a whole. This strongly supports the existence of hadronic molecules, whose studies can significantly improve our understanding on the construction of the subatomic world. To verify this picture, we propose to further investigate the $P_{cs}(4459)^0$ to examine whether it can be separated into two states, and to search for the $bar D Xi_c$ molecular state of $J^P=1/2^-$.