Two-body Strong Decays Research Articles

Strong decays of the vector tetraquark states with the masses about 4.5 GeV via the QCD sum rules

We suppose that there exist three vector hidden-charm tetraquark states with the JPC=1−− at the energy about 4.5GeV, and investigate the two-body strong decays systematically. We obtain thirty QCD sum rules for the hadronic coupling constants based on rigorous quark-hadron duality, then obtain the partial decay widths, therefore the total widths approximately, which are compatible with the experimental data of the Y(4500) from the BESIII collaboration. The Y(4500) may be one vector tetraquark state having three main Fock components, or consists of three different vector tetraquark states. We can search for the typical decays Y→D¯10D0−D¯0D102, D¯1−D+−D¯−D1+2, D¯00D⁎0−D¯⁎0D002, D¯0−D⁎+−D¯⁎−D0+2, ηcω, J/ψω to diagnose the nature of the Y(4500).

The two-body strong decays of the fully-charm tetraquark states

We study the hadronic coupling constants in the two-body strong decays of the fully-charm tetraquark states with the J^{PC}=0^{++}, 1^{+-}, and 2^{++} via the QCD sum rules based on rigorous quark-hadron duality. Then we obtain the hadronic coupling constants and partial decay widths therefore total decay widths, which support assigning the X(6552) as the first radial excitation of the scalar tetraquark state. And other predictions can be used to diagnose exotic states in the future.

Can the new states around 2.2 GeV be identified as the ω(3D)?

Recently, the BESIII Collaboration reported that there exist two explicit enhancement structures near 2.25[Formula: see text]GeV, one has the mass of [Formula: see text][Formula: see text]MeV and the width of [Formula: see text][Formula: see text]MeV and another structure has the mass of [Formula: see text][Formula: see text]MeV and the width of [Formula: see text][Formula: see text]MeV when analyzing the cross section of subprocesses. Earlier, the BESIII Collaboration reported the existence of the [Formula: see text], with a mass of [Formula: see text][Formula: see text]MeV and width of [Formula: see text][Formula: see text]MeV. Based on these experimental results, we carried out a study. We present the comparison of the mass spectrum between theoretical and experimental masses and examine the two-body strong decays of these states within two different approaches to the [Formula: see text] model. We find that the newly discovered states are most likely to be an [Formula: see text] state. This discovery could be useful in establishing entire [Formula: see text] mesons.

Strong decay properties of single heavy baryons ΛQ, ΣQ and ΩQ

Motivated by recent progresses in experiments in searching for the [Formula: see text] baryons, we systematically analyze the strong decay behaviors of single heavy baryons [Formula: see text], [Formula: see text] and [Formula: see text]. The two-body strong decay properties of [Formula: see text]-wave, [Formula: see text]-wave and some [Formula: see text]-wave states are studied with the [Formula: see text] model. The results support assigning the recently observed [Formula: see text] and [Formula: see text] as the 2S([Formula: see text]) and 1D([Formula: see text]) states, respectively. In addition, the quantum numbers of many other experimentally observed baryons are also suggested according to their strong decays. Finally, some baryons which have good potentials to be observed in experiments are predicted and the possible decay channels for searching for these predicted states are also suggested.

Further study of within a chiral quark model* *Supported by the National Natural Science Foundation of China (12175065, 12005060, 12075288, 11735003, 11961141012). Ju-Jun Xie is also supported by the Youth Innovation Promotion Association CAS

In our previous studies, we analyzed the two-body strong decays of the low-lying Ω baryon states within a chiral quark model. The results showed that the mass, total width, and two body decay could be well reproduced with the spin-parity state classified in the quark model. Stimulated by the new observations of the three-body decay process at Belle, in the present study, we further investigate the three-body strong decay within the chiral quark model. It is found that the has a sizeable decay rate into the three-body final states . When considering as the resonance, the predicted ratio is close to the upper limit measured by the Belle Collaboration in 2019; however, it is too small to be comparable to the recent measurement . In addition, the coupled-channel effects on the bare three-quark state from nearby channels , , and are studied. Our theoretical results show that the coupled-channel effects on are not very large, and the molecular component is no more than . To clarify the nature of resonance, precise measurements on the ratio are needed, and further investigation on the effects of coupled channels is recommended.

Doubly charmed dibaryon states* *Supported by the China National Funds for Distinguished Young Scientists (11825503), the National Key Research and Development Program of China (2020YFA0406400), the 111 Project (B20063), the National Natural Science Foundation of China (12175091, 11965016, 12247101, 12047501), and the project for top-notch innovative talents of Gansu province

In this work, we study the doubly charmed dibaryon states with the () configuration. The mass spectra of doubly charmed dibaryon states are obtained systematically within the chromomagnetic interaction model. In addition to the mass spectrum analysis, we illustrate their two-body strong decay behaviours. Our results suggest that there may be narrow states or even stable states that cannot decay through the strong interaction. We hope that our results will provide valuable information for further experimental searches for doubly charmed dibaryon states.

Study of the ω and ω3 , ρ and ρ3 , and the newly observed ω -like state X(2220)

We study the excited states of $\omega$ and $\omega_3$ by comparison with the $\rho$ and $\rho_3$ families, and discuss the possibility of $X(2220)$ as $\omega$ excitation by analyzing the mass spectra and strong decay behaviors. In addition, we predict the masses and widths of $\omega(2D)$ and $\omega_3$and $\rho_3(4D)$, $\rho_3(1G)$, $\omega_3$ and $\rho_3(2G)$ and $\omega_3(3G)$ and $\rho_3(3G)$. The abundant information of their two-body strong decays predicted in this work will be helpful to further study of these $\omega$ and $\omega_3$ and $\rho$ and $\rho_3$ states in experiment and theory.

Strange cousin of Z c (4020/4025) as a tetraquark state* *Supported by the National Natural Science Foundation of China (12175068)

Motivated by the analogous properties of and , we tentatively assign as the -type hidden-charm tetraquark state with , where A denotes the axialvector diquark states, and explore -type tetraquark states without strange, with strange, and with hidden-strange via QCD sum rules in a consistent manner. We then explore the hadronic coupling constants in the two-body strong decays of tetraquark states without and with strange via QCD sum rules based on rigorous quark-hadron duality and acquire partial and total decay widths. The present calculations support assigning as the -type tetraquark state with , while the predictions for its strange cousin state can be confronted with experimental data in the future.

Two-body strong decays of the 2P and 3P charmonium states

Two-body open charm strong decays of the $2P$ and $3P$ charmonium states are studied by the Bethe-Salpeter(BS) method combined with the $^3P_0$ model. The wave functions and mass spectra of the $2P$ and $3P$ charmonium states are obtained by solving the BS equation with the relativistic correction. The strong decay widths and relative ratios of the $2P$ and $3P$ charmonium states are calculated. Comparing our results with the experimental data, we obtain some interesting results. Considering the $X^*(3860)$ as the $\chi_{c0}(2P)$, the total strong decay width is smaller than the experimental data. But the strong decay width depends on the parameter $\gamma$ in the $^3P_0$ model, and the mass and width of the $X^*(3860)$ have large errors, we cannot rule out the possibility that the $X^*(3860)$ is the $\chi_{c0}(2P)$. The $X(4160)$ is a good candidate for the $\chi_{c0}(3P)$, not only the strong decay width of the $\chi_{c0}(3P)$ is same as the experimental data, but the relative ratios $\frac{\Gamma(\chi_{c0}(3P)\to D\bar D)}{\Gamma(\chi_{c0}(3P)\to D^*\bar D^*)}\approx0.0019<0.09$, and $\frac{\Gamma({\chi_{c0}(3P)\to D\bar D^*})}{\Gamma({\chi_{c0}(3P)\to D^*\bar D^*})}=0<0.22$ are consistent with the experimental results of the $X(4160)$. Taking the $X(4274)$ as the $\chi_{c1}(3P)$, the strong decay width is consistent with the experimental data, so the $X(4274)$ is a good candidate for the $\chi_{c1}(3P)$. Assigning the $X(4350)$ as the $\chi_{c2}(3P)$, the corresponding strong decay width is slightly larger than the experimental data. To identify if the $X(4350)$ is $\chi_{c2}(3P)$, many more investigations are needed. All of the strong decay widths and relative ratios of the $2P$ and $3P$ charmonium states can provide the useful information to discover and confirm these particles in the future.

Strong decays of excited 2+ charmed mesons

The new charmed resonance $ D_2^*(3000) $ was observed by the LHCb Collaboration in $ B $ decays. In this paper, by assigning it as four possible excited states of the $ 2^+ $ family, we use the instantaneous Bethe-Salpeter method to calculate their Okubo-Zweig-Iizuka-allowed two-body strong decays. The results of $ 1^3F_2 $ and $ 3^3P_2 $ states deviate from the present experimental observation while $ 2^3P_2 $ and $ 2^3F_2 $ are in the error range. Our study also reveals that the widths of these states depend strongly on the masses. Due to the large uncertainties and different mass input, variable models get inconsistent conclusions at the moment. The analysis in this work can provide essential assistance for future measurements and investigations.

Possible P -wave DsD¯s0(2317) molecular state Y′(4274)

Stimulated by the measurement of the $J\psi\phi$ decay model of $Y(4274)$ by the LHCb Collaboration, we consider a possible interpretation of this state as a hadron molecular-a bound state of $D_s$ and $\bar{D}_{s0}(2317)$ mesons. Using effective Lagrangian approach, we calculate the two-body strong decay channels $Y(4274)\to{}J/\psi\phi,\chi_{c0}\eta,\chi_{c0}\eta,D^{*}_s\bar{D}_s$, $D\bar{D}^{*}$, $K\bar{K}^{*}$, and $\phi\phi$ through hadronic loops and three-body decays into $\pi^0{}D_s\bar{D}_s$. In comparison with the LHCb data, our results show that $Y(4274)$ cannot be assigned to be a $D_s\bar{D}_{s0}(2317)$ molecular state. The calculated partial decay widths with $J^P=1^{+}$ $D_s\bar{D}_{s0}$ molecular state picture indicates that allowed decay modes, $\chi_{c0}\eta$ and $\chi_{c1}\eta$, may have the smallest branching ratio and are of the order of 0.0 MeV. Future experimental measurements of such two processes can be quite useful to test the different interpretations of the $Y(4274)$. If $P-$wave $D_s\bar{D}_{s0}$ molecular exist [we marked as $Y^{'}(4274)$], the total decay is at the order of 1.06-1.84 MeV, which seems to be within the reach of the current experiments such as Belle II. In addition, the calculated partial decay widths indicate that allowed decay mode, $D\bar{D}^{*}$, may have the biggest branching ratio. The experimental measurements for this strong decay process could be a crucial to observe such a new state $Y^{'}(4274)$.

The newly observed state D_{s0}(2590)^{+}

We choose the Reduction Formula, PCAC and Low Energy Theory to reduce the S matrix of a OZI allowed two-body strong decay involving a light pseudoscalar, the covariant transition amplitude formula with relativistic wave functions as input is derived. After confirm this method by the decay D^*(2010)rightarrow Dpi , we study the newly observed D_{s0}(2590)^{+} with supposing it to be the state D_s(2^1S_0)^+, we find its decay width Gamma is highly sensitive to the D_{s0}(2590)^{+} mass, which result in the meaningless comparison of widths by different models with various input masses. Instead of width, we studied the overlap integral over the wave functions of initial and final states, here we parameterized it as X which is model-independent, and the ratio Gamma /{|{mathbf {P}_f}|^3}, both are almost mass independent, to give us useful information. The results show that, all the existing theoretical predictions X_{D_s(2S) rightarrow D^*K}=0.25sim 0.41 and Gamma /{|{mathbf {P}_f}|^3}=0.81sim 1.77hbox {MeV}^{-2} are smaller than experimental data 0.585^{+0.015}_{-0.035} and 4.54^{+0.25}_{-0.52}hbox {MeV}^{-2}. Further compared with X^{ex}_{D^*(2010) rightarrow Dpi }=0.540pm 0.009, the current data X^{ex}_{D_s(2S) rightarrow D^*K}=0.585^{+0.015}_{-0.035} is too big to be an reasonable value, so it is early to say D_{s0}(2590)^{+} is the conventional D_s(2^1S_0)^+ meson.

Where are the hidden-charm hexaquarks?

In this work, we carry out the study of hidden-charm hexaquark states with the typical configurations $qqc\bar{q}\bar{q}\bar{c}$ ($q=u, d, s$). The mass spectra of hidden-charm hexaquark states are obtained within the chromo-magnetic interaction model. In addition to the mass spectra analysis, we further illustrate their two-body strong decay behaviors. There exist some compact bound states which cannot decay through the strong interaction. Hopefully our results will help to search for such types of the exotic states in the future experiments.

Heavy flavor pentaquarks with four heavy quarks

In this work, we carry out the study of heavy flavor pentatuarks with four heavy quarks, which have typical $QQQQ\bar q$ configuration. Within the Chromomagnetic Interaction model, the mass spectrum of these discussed $QQQQ\bar q$ 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.

Strong decays of the newly P_{cs}(4459) as a strange hidden-charm Xi _c{bar{D}}^* molecule

In our former work [arXiv:2011.07214], the P_{cs}(4459) observed by the LHCb Collaboration can be explained as a coupled strange hidden-charm Xi _c{bar{D}}^*/Xi _c^*{bar{D}}/Xi _c'{bar{D}}^*/Xi _c^*{bar{D}}^* molecule with I(J^P)=0(3/2^-). Here, we further discuss the two-body strong decay behaviors of the P_{cs}(4459) in the meson-baryon molecular scenario by input the former obtained bound solutions. Our results support the P_{cs}(4459) as the strange hidden-charm Xi _c{bar{D}}^* molecule with I(J^P)=0(3/2^-). The relative decay ratio between Lambda _cD_s^* and J/psi Lambda is around 10, where the partial decay width for the Lambda _cD_s^* channel is around 0.6 to 2.0 MeV.

Strong decays of {bar{D}}^{*}K^{*} molecules and the newly observed X_{0,1} states

Lately, the LHCb Collaboration reported the discovery of two new states in the B^+rightarrow D^+D^- K^+ decay, i.e., X_0(2866) and X_1(2904). In the present work, we study whether these states can be understood as {bar{D}}^*K^* molecules from the perspective of their two-body strong decays into D^-K^+ via triangle diagrams and three-body decays into {bar{D}}^*Kpi . The coupling of the two states to {bar{D}}^*K^* are determined from the Weinberg compositeness condition, while the other relevant couplings are well known. The obtained strong decay width for the X_0(2866) state, in marginal agreement with the experimental value within the uncertainty of the model, hints at a large {bar{D}}^*K^* component in its wave function. On the other hand, the strong decay width for the X_1(2904) state, much smaller than its experimental counterpart, effectively rules out its assignment as a {bar{D}}^*K^* molecule.

Understanding the newly observed Ξc0 states through their decays

Inspired by the newly observed $\Xi_c^0$ states by the LHCb Collaboration, we investigate the OZI-allowed two-body strong decays of the $\lambda$-mode $1P$ wave $\Xi'_c$ states within the chiral quark model. Our results indicate that: (i) the newly observed states $\Xi_c(2923)^0$ and $\Xi_c(2939)^0$ are good candidates of the $\lambda$-mode $1P$ wave $\Xi'_c$ states with the spin-parity $J^P=3/2^-$, namely $|^4P_{\lambda}3/2^-\rangle$ and $|^2P_{\lambda}3/2^-\rangle$, respectively. (ii) The another newly observed state $\Xi_c(2965)^0$ mostly corresponds to the $\lambda$-mode $1P$-wave $\Xi'_c$ state with the spin-parity $J^P=5/2^-$, namely $|^4P_{\lambda}5/2^-\rangle$. (iii) For the two $\lambda$-mode $J^P=1/2^-$ mixed states, the $|P_{\lambda}~1/2^-\rangle_1$ is a narrow state with a width of $\Gamma\sim15$ MeV and mainly decays into $\Xi'_c\pi$; while the $|P_{\lambda}~1/2^-\rangle_2$ state has a width of $\Gamma\sim52$ MeV and dominantly decays into $\Xi_c\pi$ and $\Lambda_cK$ channels. If the broad structure around $2880$ MeV observed at LHCb arises from the new $\Xi^0_c$ state, this state is very likely to be the $|P_{\lambda}~1/2^-\rangle_2$ state.

Analysis of the strong decays of Pc(4312) as a pentaquark molecular state with QCD sum rules * * Supported by National Natural Science Foundation (11775079)

In this article, we tentatively assign Pc(4312) to be the pentaquark molecular state with the spin-parity , and discuss the factorizable and non-factorizable contributions in the two-point QCD sum rules for the molecular state in detail to prove the reliability of the single pole approximation in the hadronic spectral density. We study its two-body strong decays with the QCD sum rules, and special attention is paid to match the hadron side with the QCD side of the correlation functions to obtain solid duality. We obtain the partial decay widths and , which are compatible with the experimental value of the total width, and support assigning to be the pentaquark molecular state.

Study of the ω meson family and newly observed ω -like state X(2240)

Since the present $\omega$ meson family has not been established, in this work, we carry out an investigation of the mass spectrum and Okubo-Zweig-Iizuka a allowed two-body strong decay of the $S$-wave and the $D$-wave $\omega$ mesons, and make the comparison with the experimental data of these reported $\omega$ states and the $\omega$-like $X(2240)$ state observed by BESIII. By this study, we not only suggest the possible assignments to these observed $\omega$ states under the framework of the $\omega$ meson family, but also predict three $\omega$ mesons ($\omega(5S)$, $\omega(2D)$ , and $\omega(4D)$) which are still missing in experiment. The present study may provide valuable information to further construct the $\omega$ meson family. Considering the present running status of BESIII, we also suggest that BESIII should pay more attention to the issue of $\omega$ meson with accumulating more data.

Possible interpretation of the newly observed Omega _b states

Inspired by the newly observed Omega _b states by the LHCb Collaboration, we investigate the two-body strong decays of the low-lying lambda -mode Omega _b baryons up to N=2 shell using the chiral quark model within the j-j coupling scheme. Our results indicate that: (i) the newly observed states Omega _b(6316)^- and Omega _b(6330)^- are good candidates of the light spin j=1 states, while the spin-parity J^P=1/2^- and J^P=3/2^- cannot be distinguished. The other two states, Omega _b(6340) and Omega _b(6350) mostly correspond to the light spin j=2 states, while the spin-parity J^P=3/2^- and J^P=5/2^- cannot be distinguished as well. (ii) The 2S states with spin-parity J^P=1/2^+ and J^P=3/2^+, respectively, might be narrow states with a width of Gamma <2 MeV. (iii) The 1D states are not broad and the total decay widths vary from several to dozens of MeV, which have a good potential to be observed in future experiments.