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 work, we explore the charmed pentaquarks, where the relativistic five-quark equations are obtained by the dispersion relation technique. By solving these equations with the method based on the extraction of the leading singularities of the amplitudes, we predict the mass spectrum of charmed pentaquarks with $J^P=1/2^{\pm}$ and $3/2^{\pm}$, which is valuable to further experimental study of charmed pentaquark.
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.
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…
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 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…
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…
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…
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…
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 $J^P=1/2^+$.
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,…
I study the charmed $uudd\bar c$ resonance D*p (3100) very recently discovered by the H1 collaboration at Hera. An anticharmed resonance was already predicted, in a recent publication mostly dedicated to the S=1 resonance Theta+(1540). To confirm these recent predictions, I apply the same standard quark model with a quark-antiquark annihilation constrained by chiral symmetry. I find that repulsion excludes the D*p (3100) as a $uudd\bar c$ s-wave pentaquark. I explore the D*p (3100) as a heptaquark, equivalent to a N-pi-D* linear molecule, with positive parity and total isospin I=0. I find that…
In this article, we study the axialvector-diquark-scalar-diquark-antiquark type charmed pentaquark states with $J^P={\frac{3}{2}}^\pm$ with the QCD sum rules by carrying out the operator product expansion up to the vacuum condensates of dimension $13$ in a consistent way. In calculations, we separate the contributions of the negative parity and positive parity pentaquark states unambiguously, and choose three sets input parameters to study the masses and pole residues of the charmed pentaquark states $uuuc\bar{u}$ and $sssc\bar{s}$ in details. Then we estimate the masses of the charmed pentaqu…
In this work, we adopt the one-boson-exchange model to study the $D^{(*)}K^{(*)}$ interactions. With the same parameters, we can simultaneously reproduce the masses of the $D_{s0}(2317)$, $D_{s1}(2460)$, and $T_{c\bar{s}}^{a0(++)}(2900)$ recently observed by the LHCb collaboration in the hadronic molecular picture, where the $D_{s0}(2317)$, $D_{s1}(2460)$, and $T_{c\bar{s}}^{a0(++)}(2900)$ are regarded as the $DK[I(J^P)=0(0^+)]$, $D^*K[0(1^+)]$, and $D^*K^*[1(0^+)]$ charmed-strange molecular states, respectively. In addition, we extend to study the $Λ_cK^{(*)}$ and $Σ_cK^{(*)}$ interactions an…
Assuming the two diquark structure for the pentaquark state as advocated in the Jaffe-Wilczek model, we study the strong decays of light and heavy parity-even pentaquark states using the light-front quark model in conjunction with the spectator approximation. The narrowness of the Theta width is ascribed to the p-wave configuration of the diquark pair. Taking the Theta width as a benchmark, we estimate the rates of the strong decays Xi_{3/2}-- to Xi- pi-, Sigma- K-, Sigma_{5c}0 to D_s- p, D_{s0}*- p and Xi_{5c}0 to D_s- Sigma+, D_{s0}^{*-} Sigma+ with Sigma_{5c} Xi_{5c} being antisextet charme…
H1 Collaboration recently observed the charmed pentaquark. In this short note, we point out that the dominant production mechanism for pentaquark consisting of a heavy quark is heavy quark fragmentation. We obtain a crude estimate on the fragmentation probability for charm quark into Theta_c^0, based on the known fragmentation probabilities of charm quark into mesons and baryons: f(c-bar --> Theta_c^0) =~ (2-7) x 10^{-3}. Similarly, we also obtain the fragmentation probability for bottom quark into Theta_b^+: f(b-bar --> Theta_b^+) =~ (5-20) x 10^{-3}. We also estimate the prospect of observin…
We perform a systematic exploration of the possible doubly charmed molecular pentaquarks composed of $Σ_c^{(*)}D^{(*)}$ with the one-boson-exchange potential model. After taking into account the $S-D$ wave mixing and the coupled channel effects, we predict several possible doubly charmed molecular pentaquarks, which include the $Σ_cD$ with $I(J^P) = 1/2(1/2^-)$, $Σ_c^*D$ with $1/2(3/2^-)$, and $Σ_cD^*$ with $1/2(1/2^-)$, $1/2(3/2^-)$. The $Σ_cD$ state with $3/2(1/2^-)$ and $Σ_cD^*$ state with $3/2(1/2^-)$ may also be suggested as candidates of doubly charmed molecular pentaquarks. The $Σ_cD$ a…
In this work, we discuss the electromagnetic properties of the $S$-wave $Σ_c^{(*)}D^{(*)}$-type doubly charmed molecular pentaquarks, which have close relation to their inner structures. Both the $S$-$D$ wave mixing effect and the coupled channel effect are taken into account. We analyze the magnetic moments for the $S$-wave $Σ_c^{(*)}D^{(*)}$ molecular states, and extend our theoretical framework to study the transition magnetic moments and the radiative decay widths between the $S$-wave $Σ_c^{(*)}D^{(*)}$ molecules. We discuss the relations between the magnetic moments and the transition mag…
Baryons of the type Qqqqq-bar (where Q = c,b and q = u,d,s quarks) forming anti-decapenta (15)-plets with spin-parity one half-plus are predicted on simple theoretical considerations. The lightest members of these multiplets are explicitly exotic doublets cuuds-bar, cudds-bar with mass about 2420 MeV, and buuds-bar, budds-bar with mass about 5750 MeV, only 130 MeV heavier than Lambda_c and Lambda_b, respectively, and thus stable against strong decays. Although the production rate is probably very low, these remarkable pentaquarks can be looked for at LHC, Fermilab, B-factories, RHIC and elsewh…
We construct QCD sum rules for the anti-charmed pentaquark $Θ_c (3099)$, recently reported at HERA. The sum rules are constructed similarly with the $Θ^+ (1540)$ sum rules using the anti-charmed analogue of the $Θ^+$ interpolating field. The strange quark and quark-gluon mixed condensates, which were important in the $Θ^+$ sum rules, are replaced by the gluon condensates whose contribution to the OPE is suppressed due to the heavy quark mass. Our result suggests that the parity of $Θ_c$ is positive. We identify the difference from the $Θ^+$ sum rule, which leads to the positive parity in this …
In this article, we present the scalar-diquark-scalar-diquark-antiquark type and scalar-diquark-axialvector-diquark-antiquark type pentaquark configurations in the diquark model, and study the masses and pole residues of the $J^P={\frac{1}{2}}^\pm$ hidden-charmed pentaquark states in details with the QCD sum rules by extending our previous work on the $J^P={\frac{3}{2}}^-$ and ${\frac{5}{2}}^{+}$ hidden-charmed pentaquark states. We calculate the contributions of the vacuum condensates up to dimension-10 in the operator product expansion by constructing both the scalar-diquark-scalar-diquark-a…
Inspired by the states $T_{c\bar{s}0}^{a}(2900)^{0}$ and $T_{c\bar{s}0}^{a}(2900)^{++}$ reported by the LHCb Collaboration, we carry out a systematical investigation of the charm-strange pentaquark system using resonance group method in the quark delocalization color screening model. The present results predict the existence of some bound states and resonance states with support from the study of the mass spectrum and the decay properties. Both $Σ_{c}^{\ast}K^{\ast}$ with $I(J^{P})=\frac{1}{2}(\frac{5}{2}^{-})$ and $ΔD_{s}^{\ast}$ with $I(J^{P})=\frac{3}{2}(\frac{5}{2}^{-})$ are bounded by cha…
Very recently, the LHCb Collaboration reported a fully charmed tetraquark state $X(6900)$ in the invariant mass spectrum of $J/ψ$ pairs. If one $J/ψ$ meson is replaced with a fully charmed baryon, we obtain a fully charmed pentaquark candidate. In this work, we perform a systematic study on the mass spectra of the S-wave fully heavy pentaquark $QQQQ\bar{Q}$ 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 penta…
We study hadronic molecular states in a coupled system of $J/ψN - Λ_c\bar{D}^{(*)} - Σ_c^{(*)}\bar{D}^{(*)}$ in $I(J^P) = \frac{1}{2}(\frac{3}{2}^-)$ channel, using the complex scaling method combined with the Gaussian expansion method. We construct the potential including one pion exchange and one $D^{(*)}$ meson exchange with $S$-wave orbital angular momentum. We find that the both mass and width of the pentaquark $P_c(4380)$ can be reproduced within a reasonable parameter region, and that its main decay mode is $Λ_c\bar{D}^*$. We extend our analysis to a coupled system of $Λ_c D^{(*)} - Σ_c…
We explore the possibility of observing the anti-charmed pentaquark state from the $Θ_c \bar{n} π^+$ decay of $B$ meson produced at $B$-factory experiments. We first show that the observed branching ratio of the $B^+$ to $ Λ^-_c p π^+$, as well as its open histograms, can be remarkably well explained by assuming that the decay proceeds first through the $π^+ \bar{D}^0$ (or $\bar{D}^{*0}$) decay, whose branching ratios are known, and then through the subsequent decay of the virtual $\bar{D}^0$ or $\bar{D}^{*0}$ mesons to $Λ_c^- p$, whose strength are calculated using previously fit hadronic par…
Recently, LHCb collaboration reported the observation of two hidden-charmed resonances $P_c(4380)$ and $P_c(4450)$ consistent with hidden-charmed pentaquarks. We perform a dynamical investigation about the $\bar{D}Σ_c^*(2520)$ and $\bar{D}^*Σ_c(2455)$ interactions which are described by the meson exchanges in a quasipotential Bethe-Salpeter equation approach. Two poles around $4450$ and $4390$ MeV are produced from the $\bar{D}^*Σ_c(2455)$ interaction with spin parities $3/2^-$ and $5/2^+$, respectively. The peak for $5/2^+$ state has a comparable hight as that of $3/2^-$ state in the $J/ψp$ i…
The pentaquark width is calculated in QCD sum rules. The higher dimension operators contribution is accounted. It is shown, that $Γ_Θ$ should be very small, less than $1Mev$.
In this article, we study the magnetic moment of the pentaquark state $ Θ^+(1540)$ with the QCD sum rules approach in the external electromagnetic field. The numerical results indicate the magnetic moment of the pentaquark state $ Θ^+(1540)$ is about $μ_{Θ^+}=(0.24\pm0.02)μ_N$.
The pentaquark width is calculated in QCD sum rules. Result for $Γ_Θ$ show, that $Γ_Θ$ can vary in the region less than 1$MeV$. The main conclusion is, that if pentaquark is genuine states then sum rules really predict the narrow width of pentaquark $θ^+$, and the suppression of the width is both parametrical and numerical.
The LHCb Collaboration, using its full data set from runs $1$ and $2$, announced in $2019$ a surprising update of the hidden-charm pentaquark states $P_c(4380)^+$ and $P_c(4450)^+$, observed in 2015. A new state, $P_c(4312)^+$, was clearly seen at lower energies; furthermore, the original $P_c(4450)$ resonance was resolved into two individual states, named the $P_c(4440)^+$ and the $P_c(4457)^+$. Motivated by the fact that these new hidden-charm pentaquark states were successfully predicted by our chiral quark model, we extend herein such study to the doubly charmed sector. The analyzed total …
QCD sum rule is applied to the pentaquark spectroscopy. It is concluded that no positive parity state is seen in low energy region, while there may exist negative parity states at around 1.5 GeV. Choice of interpolating local operators and relation to the lattice calculations are discussed.
In this work we investigate the consequences of the Jaffe and Wilczek diquark model in the framework of QCD sum rules. An analysis of the Theta^+(1540) as (ud)^2\bar{s} state shows that the mass of the pentaquark is compatible with the experimentally measured value. The mass difference between the Theta^+ and the pentaquark with the quantum numbers of the nucleon amounts to 70 MeV and is consistent with the interpretation of the N(1440) as a pentaquark.
In this work we study the Theta(1540) in the framework of QCD sum rules based on (ud)^2\bar{s} diquark clustering as suggested by Jaffe and Wilczek. Within errors, the mass of the pentaquark is compatible with the experimentally measured value. The mass difference between the Theta and the pentaquark with the quantum numbers of the nucleon amounts to 70 MeV, consistent with the interpretation of the N(1440) as a pentaquark.
The LHCb collaboration has recently observed three narrow pentaquark states --- the $P_c(4312)$, $P_c(4440)$, and $P_c(4457)$ ---that are located close to the $\bar{D} Σ_c$ and $\bar{D}^* Σ_c$ thresholds. Among the so-far proposed theoretical interpretations for these pentaquarks, the molecular hypothesis seems to be the preferred one. Nevertheless, in the molecular picture the spins of the $P_c(4440)$ and $P_c(4457)$ have not been unambiguously determined yet. In this letter we point out that heavy antiquark-diquark symmetry induces a model-independent relation between the spin-splitting in t…
A review is given to pentaquark mass predictions in quark models and QCD. It is pointed out that no successful quark model prediction is available for low-lying pentaquark states. Some new results of direct application of QCD, QCD sum rules and lattice QCD, are also presented.
In a diquark-diquark-antiquark picture of the pentaquark we study the decay $Θ\to K^{+} n$ within the framework of QCD sum rules. After evaluation of the relevant three-point function, we extract the coupling $g_{ΘnK}$ which is directly related to the pentaquark width. Restricting the decay diagrams to those with color exchange between the meson-like and baryon-like clusters reduces the coupling constant by a factor of four. Whereas a small decay width might be possible for a positive parity pentaquark, it seems difficult to explain the measured width for a pentaquark with negative parity.
In a diquark-diquark-antiquark picture of the pentaquark we study the decay $Θ\rightarrow K^{+} n$ within the framework of QCD sum rules. After evaluation of the relevant three-point function, we extract the coupling $g_{ΘnK}$ which is directly related to the pentaquark width. Restricting the decay diagrams to those with color exchange between the meson-like and baryon-like clusters reduces the coupling constant by a factor of four. Whereas a small decay width might be possible for a positive parity pentaquark, it seems difficult to explain the measured width for a pentaquark with negative par…
In this article, we construct the scalar-diquark-axialvector-diquark-antiquark type interpolating currents, and study the masses and pole residues of the $J^{P}=\frac{3}{2}^{\pm}$ hidden-charmed pentaquark states with the QCD sum rules. In calculations, we use the formula $μ=\sqrt{M^2_{P}-(2{\mathbb{M}}_c)^2}$ to determine the energy scales of the QCD spectral densities. We obtain the masses of the hidden-charm pentaquark states with the strangeness $S=-1$ and $S=-2$, which can be confronted to the experimental data in the future.
In the article, we investigate the diquark-diquark-antiquark type fully-heavy pentaquark states with the spin-parity $J^P={\frac{1}{2}}^-$ via the QCD sum rules, and obtain the masses $M_{cccc\bar{c}}=7.93\pm 0.15\,\rm{GeV}$ and $M_{bbbb\bar{b}}=23.91\pm0.15\,\rm{GeV}$. We can search for the fully-heavy pentaquark states in the $J/ψΩ_{ccc}$ and $ΥΩ_{bbb}$ invariant mass spectrum in the future.
Pentaquark baryons $Θ^{+}$ and $Ξ^{--}$ are studied in the dual gravity theory of QCD in which simple mass formulae of pentaquarks are derived in the Maldacena prototype model for supersymmetric QCD and a more realistic model for ordinary QCD. In this approach it is possible to explain the extremely narrow decay widths of pentaquarks. With the aim of constructing more reliable mass formulae, a sketch is given on spin and the hyperfine interaction in the string picture.
Using configuration space techniques, we calculate next-to-leading order (NLO) five-loop QCD corrections to the correlators of interpolating pentaquark currents in the limit of massless quarks. We obtain very large NLO corrections to the spectral density which makes a standard sum rule analysis problematic. However, the NLO corrections to the correlator in configuration space are reasonable. We discuss the implications of our results for the phenomenological sum rule analysis of pentaquark states.
We perform a systematic study on the interactions of the $Σ_c^{(*)}D^{(*)}$ systems within the framework of chiral effective field theory. We introduce the contact term, one-pion-exchange and two-pion-exchange contributions to describe the short-, long-, and intermediate-range interactions. The low energy constants of the $Σ_c^{(*)}D^{(*)}$ systems are estimated from the $N\bar{N}$ scattering data by introducing a quark level Lagrangian. With three solutions of LECs, all the $Σ_c^{(*)}D^{(*)}$ systems with isospin $I=1/2$ can form bound states, in which different inputs of LECs may lead to dis…
In this work, we explore a systematic investigation on $S$-wave interactions between a doubly charmed baryon $Ξ_{cc}(3621)$ and a charmed meson in a $T$ doublet $(D_1,\,D_2^*)$. We first analyze the possibility for forming $Ξ_{cc}D_1/Ξ_{cc}D_2^*$ bound states with the heavy quark spin symmetry. Then, we further perform a dynamical study on the $Ξ_{cc}D_1/Ξ_{cc}D_2^*$ interactions within a one-boson-exchange model by considering both the $S$-$D$ wave mixing and coupled channel effect. Finally, our numerical results conform the proposals from the heavy quark spin symmetry analysis: the $Ξ_{cc}D_…
Very recently, two hidden-charmed resonances $P_c(4380)$ and $P_c(4450)$ consistent with pentaquark states were observed at the LHCb detector. The two $P_c$ states locate just below the $\bar{D}Σ^*_c$ and $\bar{D}^*Σ_c$ thresholds with mass of gaps about 5 and 15 MeV, respectively. Inspired by this fact we perform a dynamical investigation about the $\bar{D}Σ_c^*(2520)$ and $\bar{D}^*Σ_c(2455)$ interactions which are described by the meson exchanges. A bound state which carries spin-parity $J^P=3/2^-$ is produced from the $\bar{D}Σ^*_c(2520)$ interaction, which is consistent with the $P_c(4380…
In this article, we study the magnetic moment of the pentaquark state $ Θ^+(1540)$ as diquark-diquark-antiquark ($[ud][ud]\bar{s}$) state in the framework of the light-cone QCD sum rules approach. The numerical results indicate the magnetic moment of the pentaquark state $ Θ^+(1540)$ is about $μ_{Θ^+}=-(0.49\pm 0.06)μ_N$.
In this article, we study the pentaquark state $ Θ^+(1540)$ with a (scalar)diquark-(pseudoscalar)diquark-antiquark type interpolating current in the framework of the QCD sum rules approach by including the contributions from the direct instantons. The numerical results indicate that the contributions from the direct instantons are very small and can be safely neglected.
An attempt to study recently observed Pentaquark baryons is performed in the dual string theory of QCD. Mass formulae for Pentaquark baryons are naively estimated in the Maldacena's prototype model for supersymmetric QCD and a more realistic model for the ordinary QCD.
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 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…
We perform a QCD sum rule calculation to determine the mass and the parity of the lowest lying pentaquark state. We include operators up to dimension $d=13$ in the OPE and the direct instanton contributions. We find evidence for a positive parity state. The contribution from operators of dimension $d>5$ is instrumental in determining the parity of the state and achieving the convergence of the sum rule.
