In this article, we illustrate how to calculate the hadronic coupling constants of the pentaquark states with the QCD sum rules based on rigorous quark-hadron quality, then study the hadronic coupling constants of the lowest diquark-diquark-antiquark type hidden-charm pentaquark state with the spin-parity $J^P={\frac{1}{2}}^-$ in details, and calculate the partial decay widths. The total width $Γ(P_c)=14.32\pm3.31\,\rm{MeV}$ is compatible with the experimental value $Γ_{P_c(4312)} = 9.8\pm2.7^{+ 3.7}_{- 4.5} \mbox{ MeV}$ from the LHCb collaboration, and favors assigning the $P_c(4312)$ to be the $[ud][uc]\bar{c}$ pentaquark state with the $J^P={\frac{1}{2}}^-$. The hadronic coupling constants have the relation $|G_{PD^-Σ_c^{++}}|= \sqrt{2}|G_{P\bar{D}^0Σ_c^+}|\gg |G_{P\bar{D}^0Λ_c^+}|$, and favor the hadronic dressing mechanism. The $P_c(4312)$ maybe have a diquark-diquark-antiquark type pentaquark core with the typical size of the $qqq$-type baryon states, the strong couplings to the meson-baryon pairs $\bar{D}Σ_c$ lead to some pentaquark molecule components, and the $P_c(4312)$ maybe spend a rather large time as the $\bar{D}Σ_c$ molecular state.
A new interpretation of intrinsic charm phenomenon based on the assumption of pentaquark $\left| u u d c\bar{c} \right>$ mixing with a proton is offered. The structure function of the $c$-quark in the pentaquark is constructed. Mixing different states is considered theoretically and using experiment data on $D$-meson production and inclusive production of the hidden charm particles.
In this article, we construct the scalar-diquark-scalar-diquark-antiquark type current to study the ground state triply charmed pentaquark states with the QCD sum rules. We separate the contributions of the negative-parity and positive parity triply charmed pentaquark states explicitly, and take the energy scale formula $μ=\sqrt{M^2_{P}-(3{\mathbb{M}}_c)^2}$ to determine the optimal energy scales of the QCD spectral densities. The predicted pentaquark masses can be confronted to the experimental data in the future.
We study one possible production mechanism for hidden charm pentaquark in e+e- collision, where it is produced via a color-octet c \bar c pair fragmentation. The pentaquark production at B factory energy is dominated by e+e- to c \bar c g to Pc + X. At Z^0 pole, for the pentaquark production, there are several partonic processes playing significant role. Our results show that it is possible to search for the direct pentaquark production signal at e+e- colliders, which is important to understand the properties of pentaquark.
Using the experimental data on pentaquarks with a hidden charm, new upper limits on the intrinsic charm in the proton are obtained, possible shapes of heavy quark distributions inside the proton are discussed.
We consider decays of the hidden charm LHCb pentaquarks in the hadrocharmonium and molecular scenarios. In both pictures the LHCb pentaquarks are essentially nonrelativistic bound states. We develop a semirelativistic framework for calculation of the partial decay widths that allows the final particles to be relativistic. Using this approach we calculate the decay widths in the hadrocharmonium and molecular pictures. Molecular hidden charm pentaquarks are constructed as loosely bound states of charmed and anticharmed hadrons. Calculations show that molecular pentaquarks decay predominantly int…
We use QCD sum rules to study the possible existence of a Θc(3250) charmed pentaquark. We consider the contributions of condensates up to dimension-10 and work at leading order in α_s. We obtain m(Θc) = (3.21 +/- 0.13) GeV, compatible with the mass of the structure seen by BaBar Collaboration in the decay channel B- -> p- Σc++ pi- pi-. The proposed state is compatible with a previous proposed pentaquark state in the anti-charmed sector.
In this article, we restudy the ground state mass spectrum of the diquark-diquark-antiquark type $uudc\bar{c}$ pentaquark states with the QCD sum rules by carrying out the operator product expansion up to the vacuum condensates of $13$ in a consistent way. The predicted masses support assigning the $P_c(4312)$ to be the hidden-charm pentaquark state with $J^{P}={\frac{1}{2}}^-$, assigning the $P_c(4440)$ to be the hidden-charm pentaquark state with $J^{P}={\frac{1}{2}}^-$, ${\frac{3}{2}}^-$ or ${\frac{5}{2}}^-$, assigning the $P_c(4457)$ to be the hidden-charm pentaquark state with $J^{P}={\fr…
Non-strange and strange pentaquaks with hidden charm are considered as diquark-diquark-antiquark composite systems. Spin and isospin content of such exotic states is discussed and masses are evaluated.
This paper calculates the magnetic moments of the hidden-charm strange pentaquark states with a quantum number of $J^P={\frac{1}{2}}^{\pm}$, ${\frac{3}{2}}^{\pm}$, ${\frac{5}{2}}^{\pm}$, and ${\frac{7}{2}}^{+}$ in the molecular, diquark-diquark-antiquark, and diquark-triquark models, respectively. Numerical results demonstrate that the magnetic moments change for a different spin-orbit coupling with the same model and when involving different models with the same angular momentum.
In the paper, we study the production of pentaquark $\bar{c}q qqq$ from singly bottom baryon. The tensor representations of pentaquark $\bar{c}q qqq$ are completed at first. Under the light quark symmetry analysis, we decompose the singly charmed pentaquarks into $6$, $15$ and $15'$ multiple states, and deduce the representations of these states. Then we construct the production Hamiltonian of the multiple states in proper order. For completeness, we systematically study the production channels of pentaquark states, including the possible production amplitudes and cross section relations betwe…
In a one-boson-exchange model, we study molecular states of double-charm baryon ($Ξ_{cc}(3621)$) and a charmed meson ($D$ and $D^*$). Our model indicates that there exist two possible triple-charm molecular pentaquarks, a $Ξ_{cc}D$ state with $I(J^P)=0(1/2^-)$ and a $Ξ_{cc}D^*$ state with $I(J^P)=0(3/2^-)$. In addition, we also extend our formula to explore $Ξ_{cc}\bar{B}^{(*)}$, $Ξ_{cc}\bar{D}^{(*)}$, and $Ξ_{cc}B^{(*)}$ systems, and find more possible heavy flavor molecular pentaquarks, a $Ξ_{cc}\bar{B}$ state with $I(J^P)=0(1/2^-)$, a $Ξ_{cc}\bar{B}^*$ state with $I(J^P)=0(3/2^-)$, and $Ξ_{…
We present a QCD sum rule analysis for the anti-charmed pentaquark state with and without strangeness. While the sum rules for most of the currents are either non-convergent or dominated by the $DN$ continuum, the one for the non-strange pentaquark current composed of two diquarks and an antiquark, is convergent and has a structure consistent with a positive parity pentaquark state after subtracting out the $DN$ continuum contribution. Arguments are presented on the similarity between the result of the present analysis and that based on the constituent quark models, which predict a more stable…
In two recent papers, we used the hadro-quarkonium model to study the properties of hidden-charm and bottom tetraquarks and pentaquarks. Here, we extend the previous results and calculate the masses of heavy-quarkonium-kaon/hyperon systems. We also compute the spectrum of hidden-charm and bottom tetraquarks with strangeness in the compact tetraquark (diquark-antidiquark) model. If heavy-light exotic systems with non-null strangeness content were to be observed experimentally, it might be possible to distinguish among the large variety of available theoretical pictures for tetra- and pentaquark…
I give a brief comment on the LHCb's discovery of $P_c$ and $P_{cs}$ pentaquark states. These pentaquark states not only reveal a new kind of hadronic molecules, but also shed new light on the possible structure of pentaquark components in baryons, hence may play very important role for understanding un-quenching dynamics and the whole baryon spectroscopy.
In this study, pentaquark Pc(4380) composed of a baryon sigma_c and a D_* meson is considered. Pentaquark is as a bound state of two-body systems composed of a baryon and a meson. The calculated potential will be expanded and replaced in the Schrodinger equation until tenth sentences of expansion. Solving the Schrodinger equation with the expanded potential of Pentaquark leads to an analytically complete approach. As a consequence, the binding energy EB of pentaquark Pc and wave function are obtained. The results EB will presented in the form of tables so that we can review the existence of pe…
In this paper the masses and decay processes of several new strange, charmed and bottomed exotic pentaquarks are predicted. Multiquarks are studied microscopically in a standard quark model. In pure ground-state pentaquarks the short-range interaction is computed and it is shown to be repulsive. The long-range and medium-range interactions are not expected to provide sufficient attraction. An additional quark-antiquark pair is then considered, and this is suggested to produce a narrow linear molecular system. The quarks assemble in three hadronic clusters, and the central hadron provides stabi…
In this article, we study the scalar-diquark-scalar-diquark-antiquark type $udsc\bar{c}$ pentaquark state with the QCD sum rules, the predicted mass $M_P=4.47\pm0.11\,\rm{GeV}$ is in excellent agreement with the experimental data $ 4458.8 \pm 2.9 {}^{+4.7}_{-1.1} \mbox{ MeV}$ from the LHCb collaboration, and supports assigning the $P_{cs}(4459)$ to be the hidden-charm pentaquark state with the spin-parity $J^P={\frac{1}{2}}^-$. We take into account the flavor $SU(3)$ mass-breaking effect, and estimate the mass spectrum of the diquark-diquark-antiquark type $udsc\bar{c}$ pentaquark states with …
In the framework of quark delocalization color screening model, the three new reported pentaquarks $P_{c}(4312)$, $P_{c}(4440)$, and $P_{c}(4457)$ can be identified as the hidden-charm molecular states $Σ_{c}D$ with $J^{P}=\frac{1}{2}^{-}$, $Σ_{c}D^{*}$ with $J^{P}=\frac{3}{2}^{-}$, and $Σ_{c}D^{*}$ with $J^{P}=\frac{1}{2}^{-}$, in the baryon-meson scattering process, respectively. Besides, the $Σ^{*}_{c}D^{*}$ of both $J^{P}=\frac{1}{2}^{-}$ and $J^{P}=\frac{3}{2}^{-}$ are also possible molecular pentaquarks. Moreover, the calculation is extended to the $P_{c}-$like molecular pentaquarks $P_{…
We propose to study the pentaquark candidates of $P_c^+(4380)$ and $P_c^+(4450)$ in $J/ψ$ photoproduction and look for further experimental evidence for their nature. Since the photoproduction process does not satisfy the so-called "anomalous triangle singularity" condition their presence in $J/ψ$ photoproduction would conclude that they should be genuine states and provide further evidence for their existence.
We consider hidden charm pentaquarks as hadroquarkonium states in a QCD inspired approach. Pentaquarks arise naturally as bound states of quarkonia excitations and ordinary baryons. The LHCb $P_c(4450)$ pentaquark is interpreted as a $ψ'$-nucleon bound state with spin-parity $J^P=3/2^-$. The partial decay width $Γ(P_c(4450)\to J/ψ+N)\approx 11$ MeV is calculated and turned out to be in agreement with the experimental data for $P_c(4450)$. The $P_c(4450)$ pentaquark is predicted to be a member of one of the two almost degenerate hidden-charm baryon octets with spin-parities $J^{P}=1/2^-,3/2^-$.…
Very recently, LHCb experiment announced the observation of hidden-charm pentaquark states $P_c(4312)$, $P_c(4440)$, and $P_c(4457)$ near the $ Σ_c \bar{D}$ and $ Σ_c \bar{D}^\ast$ thresholds, respectively. In this present work, we studied thesepentaquarks in the framework of the nonrelativistic quark model with four types of potential. We solved 5-body Schrödinger equation by using artificial neural network method and made predictions of parities for these states which are not determined in the experiment yet. The mass of another possible pentaquark state near the $\bar{D}^\ast Σ_c^\ast$ with…
The hidden charm pentaquark state $P_c(4450)$ observed recently by the LHCb collaboration may be of molecular nature, as advocated by some unitary approaches that also predict pentaquark partners in the strangeness $S=-1$ sector. In this work we argue that a hidden-charm strange pentaquark could be seen from the decay of the $Λ_b$, just as in the case of the non-strange $P_c(4450)$, but looking into the $J/ψηΛ$ decay mode and forming the invariant mass spectrum of $J/ψΛ$ pairs. In the model presented here, which assumes a standard weak decay topology and incorporates the hadronization process …
Inspired by the very recently discovered tetraquark states $T_{c\bar s 0}^a(2900)^{0,++}$ from the LHCb Collaboration, we predict the existence of a new charmed-strange pentaquark system, $c\bar s nnn$, which is closely connected to $c\bar s n\bar n$ by exchanging $\bar n$ into $nn$ with $n=u,d$. Especially, it is suggested to experimentally search for the predicted new pentaquark system via the weak decays of $B$ mesons or $b$-baryons, with the support from the study of the mass spectrum and the decay properties. The predicted new pentaquark system must attract extensive attention from experi…
A dynamical calculation of the strange hidden charm pentaquark systems $Λ_{c\bar{c}}$ is performed in the framework of the quark delocalization color screening model. The effective potentials between two clusters are calculated to investigate the interaction between the baryons and mesons. The dynamic calculations indicate that the strange hidden charm pentaquark system with $IJ^{P}=0\frac{1}{2}^{-}$ and $IJ^{P}=0\frac{3}{2}^{-}$ can form bound states with the help of the channel-coupling. The energies of these two system are 4094.3 MeV and 4207.4 Mev, respectively. These two $Λ_{c\bar{c}}$ st…
The diquark-diquark-antiquark model describes pentaquark states both in terms of quarks and hadrons. The latest LHCb data for pentaquarks with open charm emphasize the importance of hadron components in the structure of pentaquarks. We discuss pentaquark states with hidden charm $P(\bar c cuud)$ and those with open charm $P(\bar uussc)$ which were discovered recently in LHCb data ($J/Ψp$ and $Ξ_c^+ K^-$ spectra correspondingly). Considering the observed states as members of the lowest (s-wave) multiplet we discuss the mass splitting of states and the dumping of their widths.
The properties of pentaquarks containing a heavy anti-quark and strange quarks are studied in the bound state picture. In the flavor SU(3) limit, there are many pentaquark states with the same binding energy. When the SU(3) symmetry breaking effects are included, however, three states become particularly stable due to a ``Gell-Mann--Okubo mechanism''. They are the $\bar Qsuud$ and $\bar Qsudd$ states discussed by Lipkin, and a a previously unstudied $\bar Qssud$ state. These states will have $J^P={1\over2}^+$ and their masses are estimated. These states, if exist, may be seen in experiments in…
The LHCb has discovered two new states with preferred $J^P$ quantum numbers $3/2^-$ and $5/2^+$ from $Λ_b$ decays. These new states can be interpreted as hidden charm pentaquarks. It has been argued that the main features of these pentaquarks can be described by diquark model. The diquark model predicts that the $3/2^-$ and $5/2^+$ are in two separate octet multiplets of flavor $SU(3)$ and there is also an additional decuplet pentaquark multiplet. Finding the states in these multiplets can provide crucial evidence for this model. The weak decays of b-baryon to a light meson and a pentaquark ca…
The $J/ψp$ signals at 4380 MeV and 4450 MeV which were seen by the LHCb collaboration in the decay $Λ^0_b\to K^-J/ψp$ are discussed following the hypothesis of the existence of diquark-diquark-antiquark composite states. The discussed problems concern: (i) estimation of masses and mass splittings for low-lying states, (ii) determination of decay modes in the quark recombination scheme, (iii) unitarity and analyticity constrains for pentaquark propagators, (iv) hadronic deuteron-like components in the diquark-diquark-antiquark multiplet.
The pentaquark $P_c^+(4450)$ recently discovered by LHCb has been interpreted as a bound state of $Ψ(2S)$ and nucleon. The charmonium-nucleon interaction which provides the binding mechanism is given, in the heavy quark limit, in terms of charmonium chromoelectric polarizabilities and densities of the nucleon energy-momentum tensor (EMT). In this work we show in model-independent way, by exploring general properties of the effective interaction, that $Ψ(2S)$ can form bound states with nucleon and $Δ$. Using the Skyrme model to evaluate the effective interaction in the large-$N_c$ limit and est…
In this talk, multiquarks are studied microscopically in a standard quark model. In pure ground-state pentaquarks the short-range interaction is computed and it is shown to be repulsive, a narrow pentaquark cannot be in the groundstate. As a possible excitation, an additional quark-antiquark pair is then considered, and this is suggested to produce linear molecular system, with a narrow decay width. This excitation may be energetically favourable to the p-wave excitation suggested by the other pentaquark models. Here, the quarks assemble in three hadronic clusters, and the central hadron provi…
The recent abundant observations of pentaquarks and tetraquarks by high-energy accelerator facilities indicate the realization of the conjecture by Gell-Mann and Zweig, and by De Rujula, Georgi and Glashow [1-3]. We construct a coupled-channel model for the hidden-charm pentaquarks with strangeness whose quark content is $udsc \bar c$, $P_{cs}$, described as $ Λ_c \bar{D}_s^{(*)}, Ξ_c^{('*)} \bar{D}^{(*)}$ molecules coupled to the five-quark states. These molecules are formed by the suitable cooperation of heavy quark and chiral symmetries. We reproduce the experimental mass and quantum number…
Recently, a new hidden-charm pentaquark state $P_{cs}(4459)$ was reported by the LHCb Collaboration. Stimulated by the fact that all hidden-charm pentaquark states in $S=0$ systems were successfully predicted by our chiral quark model, we extended this study to the $S=-1$ systems. All possible quantum numbers $IJ^P=0(\frac{1}{2})^-$, $0(\frac{3}{2})^-$, $0(\frac{5}{2})^-$, $1(\frac{1}{2})^-$, $1(\frac{3}{2})^-$ and $1(\frac{5}{2})^-$ have been investigated. The calculation results shows that the newly observed state $P_{cs}(4459)$ can be explained as $Ξ_c \bar{D}^*$ molecular state and the qua…
We study the $S$-wave $DΞ$ bound state in the Bethe-Salpeter formalism in the ladder and instantaneous approximations. With the kernel generated by the hadronic effective Lagrangian, two open-charmed bound states, which quantum numbers are $I=0$, $J^P=(\frac{1}{2})^-$ and $I=1$, $J^P=(\frac{1}{2})^-$, respectively, are predicted as new candidates of hadronic pentaquark molecules in our formalism. If existing, they could contribute to the broad 3188 eV structure near the five new narrow $Ω_c$ states observed recently by the LHCb Collaboration.
The newly observed $Θ^+$ resonance is believed to be a pentaquark with the constituent quarks $uudd\bar s$. There are a few options for the constituent quark structure. Some advocate diquark-diquark-antiquark $(ud)$-$(ud)$-$\bar s$ while others favor diquark-triquark $(ud)$-$(ud\bar s)$. We use the color-spin hyperfine interaction to examine the energy levels of these structures, and we find that the diquark-diquark-antiquark structure is slight favored. We proceed to write down the flavor triplet and antisextet of the charmed or bottomed exotic baryons with internal $qqqq\bar Q$ quarks. We al…
In this article, we investigate the $\bar{D}Σ_c$, $\bar{D}Ξ^\prime_c$, $\bar{D}Σ_c^*$, $\bar{D}Ξ_c^*$, $\bar{D}^{*}Σ_c$, $\bar{D}^{*}Ξ^\prime_c$, $\bar{D}^{*}Σ_c^*$ and $\bar{D}^{*}Ξ_c^*$ pentaquark molecular states with strangeness and without strangeness via the QCD sum rules at length, pay much attention to the light flavor $SU(3)$ breaking effects, and make predictions for new pentaquark molecular states besides assigning the $P_c(4312)$, $P_c(4380)$, $P_c(4440)$, $P_c(4457)$ and $P_{cs}(4459)$ self-consistently. We can search for those pentaquark molecular states in the decays of the $Λ_b…
In a previous work we presented a theoretical analysis of the $Λ_b \to J/ψK^- p$ reaction from where a recent experiment by the LHCb collaboration at CERN claimed the existence of two hidden charm pentaquarks, $P_c(4380)^+$ and $P_c(4450)^+$. In that work we focused only on the $Λ(1405)$ and $P_c(4450)^+$ signals and discussed the possible explanation of this pentaquark state within the picture of a dynamical meson-baryon molecule made up mostly from $\bar D^* Σ_c$ and $\bar D^* Σ^*_c$ components. In the present work we improve upon the previous one by considering the total $K^- p$ and $J/ψp$ …
Electro-production of several pentaquark states is investigated in this paper. eSTARlight package is adapted to study the electro-production of $J/ψ$ and $Υ(1S)$ via pentaquark $P_c$ and $P_b$ resonance channels in $e p \to e eJ/ψp$ and $e p \to eΥ(1S) p$ scattering processes at proposed electron-ion colliders (EICs). The results in this paper are compared to the non-resonance $t$-channels, which is described in pomeron exchange model in our studies. Some pseudo-rapidity distributions rapidity distributions of $J/ψ$ and $Υ(1S)$ are presented for proposed EICs including EicC and EIC-US. It is f…
The antiquark-diquark-diquark model describes pentaquark states both in terms of quarks and hadrons. We discuss pentaquark states with hidden charm $P(\bar c cuud)$ discovered in the $J/Ψp$ spectrum by the LHCb collaboration. We consider three pentaquark states as members of the lowest ($S$-wave) multiplet and discuss the mass splitting scheme. The latest LHCb data for pentaquarks with hidden charm provide an opportunity to make an assumption about the diquark content of the pentaquark states. We give a classification for the LHCb pentaquarks and define recombination channels for these states.
A new type of charm pentaquark $P_{cs}$ with quark content $c\bar{c}uds$ in light-flavor singlet state is studied in the quark model. This state is analogous to the $P_{c}$ with $c\bar{c}uud$ in light-flavor octet, which was observed in LHC in 2015. Considering various combinations of color, spin and light flavor as internal quantum numbers in $P_{cs}$, we investigate the mass ordering of the $P_{cs}$'s by adopting both the one-gluon exchange interaction and the instanton-induced interaction in the quark model. The most stable configuration of $P_{cs}$ is identified to be total spin $1/2$ in w…
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 $IJ^P=1/2\left(3/2^-\right)$, the $P_c(4457)^+$ state could be explained as a hidden charm pentaquark state with $IJ^P=1/2\left(5/2^-\right)$, and the $P_{cs}(4459)^+$ state could be explained as a hidden charm pentaquark state wit…
We adopt the chiral perturbation theory to calculate the $Σ_{c}^{(*)}\bar{D}^{(*)}$ interaction to the next-to-leading order (NLO) and include the couple-channel effect in the loop diagrams. We reproduce the three $P_c$ states in the molecular picture after including the $Λ_{c}\bar{D}^{(*)}$ intermediate states. We also discuss some novel observations arising from the loop diagrams.
We study the masses and lifetimes of doubly charmed pentaquark $P_{cc\bar qqq}(q=u,d,s)$ primarily. The operation of masses carried out by the doubly heavy triquark-diquark model, whose results suggests the existence of stable states $cc\bar s ud$ with the parity $J^P=\frac{1}{2}^-$. The roughly calculation about lifetimes show the short magnitudes, $(4.65^{+0.71}_{-0.55})\times 10^{-13}s $ for the parity $J^P=\frac{1}{2}^-$ and $(0.93^{+0.14}_{-0.11})\times 10^{-12} s $ for $J^P=\frac{3}{2}^-$. Since the pentaquark $cc\bar s ud$ is interpreted as the stable bound states against strong decays,…
A diquark model is used to investigate single charmed baryons. In this model, baryon is composed of two diquarks and an antiquark. Masses of lowest lying states with $J^P= 1/2 ^ \pm$ are obtained. Some masses are smaller than other theoretic predictions which indicates that these baryons of pentaquark structure could be relatively stable. The results also show that $Λ(2882)$ may be a pentaquark with $J^P=1/2^-$ and $Ξ(3125)$ may be a pentaquark with $J^P=1/2^+$.
Stimulated by the meson-baryon molecular interpretations of the $P_c$ states ($P_c(4312)/P_c(4440)/P_c(4457)$), we systematically study the interactions between an $S-$wave charm-strange baryon $Ξ_c^{(\prime,*)}$ and an anti-charmed meson $\bar{D}^{(*)}$ in a coupled channel analysis. Effective potentials for the $Ξ_c^{(\prime,*)}\bar{D}^{(*)}$ interactions in a one-boson-exchange model can be related to those in the $Σ_c^{(*)}\bar{D}^{(*)}$ systems by using the $SU(3)$ flavor symmetry and heavy quark symmetry. Our results can predict several promising hidden-charm molecular pentaquarks with s…
