arXiv subjects

Hua-Xing Chen

Publications and source records attributed to Hua-Xing Chen.

At least 73 records · Page 4Linked to original sources

arXiv2022

Newly observed $a_0(1817)$ as the scaling point of constructing the scalar meson spectroscopy

Stimulated by the newly observed $a_0(1817)$ by the BESIII Collaboration, we find a perfect Regge trajectory composed of the $a_0(980)$, $a_0(1450)$, and $a_0(1817)$, which leads us to categorize the $a_0(980)$, $a_0(1450)$, and $a_0(1817)$ into the isovector scalar meson family. This scenario is supported by their two-body Okubo-Zweig-Iizuka allowed strong decay behaviors. In this scheme, we also predict the third radial excitation of the $a_0(980)$, which is denoted as the $a_0(2115)$, accessible at future experiment as a direct test of this assignment. We find another Regge trajectory which contains three isoscalar scalar states $f_0(980)$, $X(1812)$, and $f_0(2100)$. We investigate their two-body Okubo-Zweig-Iizuka allowed strong decay patterns, which are roughly consistent with the experimental data. The $f_0(980)$, $X(1812)$, and $f_0(2100)$ can be well grouped into the isoscalar scalar meson family. We want to emphasize that these two Regge trajectories have a similar slope. In summary, the present work provides a scheme of constructing the scalar meson family based on these reported scalar states. The possibility of the $f_0(1710)$ as the candidate of the scalar glueball cannot be excluded by the observation of the $a_0(1817)$ since the $a_0(1817)$ is more suitable as the isovector partner of the $X(1812)$.

hep-ph↗

arXiv2022

Hidden-charm pentaquark states through the current algebra: From their productions to decays

There may exist seven $\bar D^{(*)} Σ_c^{(*)}$ hadronic molecular states. We construct their corresponding interpolating currents, and calculate their masses and decay constants using QCD sum rules. Based on these results, we calculate their relative production rates in $Λ_b^0$ decays through the current algebra, i.e., $\mathcal{B}(Λ_b^0 \to P_c K^-):\mathcal{B}(Λ_b^0 \to P_c^\prime K^-)$ with $P_c$ and $P_c^\prime$ two different states. We also study their decay properties through the Fierz rearrangement, and further calculate these ratios in the $J/ψp$ mass spectrum, i.e., $\mathcal{B}(Λ_b^0 \to P_c K^- \to J/ψp K^-):\mathcal{B}(Λ_b^0 \to P_c^\prime K^- \to J/ψp K^-)$. Our results suggest that the $\bar D^{*} Σ_c^{*}$ molecular states of $J^P = 1/2^-$ and $3/2^-$ are possible to be observed in future experiments.

hep-ph↗

arXiv2022

Hadronic molecules in B decays

There are eighteen possibly existing $D^{(*)} \bar D^{(*)}$, $D^{(*)} \bar K^{(*)}$, and $D^{(*)} D_s^{(*)-}$ hadronic molecular states. We construct their corresponding interpolating currents, and calculate their masses and decay constants using QCD sum rules. Based on these results, we calculate their relative production rates in $B$ and $B^*$ decays through the current algebra, and calculate their relative branching ratios through the Fierz rearrangement, as summarized in Table III. Our results support the interpretations of the $X(3872)$, $Z_c(3900)$, $Z_c(4020)$, and $X_0(2900)$ as the molecular states $D \bar D^*$ of $J^{PC} = 1^{++}$, $D \bar D^*$ of $J^{PC} = 1^{+-}$, $D^* \bar D^*$ of $J^{PC} = 1^{+-}$, and $D^* \bar K^*$ of $J^P = 0^{+}$, respectively. Our results also suggest that the $Z_{cs}(3985)$, $Z_{cs}(4000)$, and $Z_{cs}(4220)$ are strange partners of the $X(3872)$, $Z_c(3900)$, and $Z_c(4020)$, respectively. In the calculations we estimate the lifetime of a weakly-coupled composite particle $A = |BC\rangle$ to be $1/t_A \approx 1/t_B + 1/t_C + Γ_{A \to BC} + \cdots$, with $\cdots$ partial widths of other possible decay channels.

hep-ph↗

arXiv2022

QCD axial anomaly enhances the $ηη^\prime$ decay of the hybrid candidate $η_1(1855)$

We study the hybrid mesons with the exotic quantum number $I^GJ^{PC} = 0^+1^{-+}$ and investigate their decays into the $ηη^\prime$, $a_1(1260) π$, $f_1(1285) η$, $f_1(1420) η$, $K^*(892) \bar K$, $K_1(1270) \bar K$, and $K_1(1400) \bar K$ channels. We find that the QCD axial anomaly enhances the decay width of the $ηη^\prime$ channel although this mode is strongly suppressed by the small $P$-wave phase space. Our results support the interpretation of the $η_1(1855)$ recently observed by BESIII as the $\bar s s g$ hybrid meson of $I^GJ^{PC}=0^+1^{-+}$. The QCD axial anomaly ensures the $ηη^\prime$ decay mode to be a characteristic signal of the hybrid nature of the $η_1(1855)$.

hep-ph↗

arXiv2022

Substructure of Multiquark Hadrons (Snowmass 2021 White Paper)

In recent years there has been a rapidly growing body of experimental evidence for existence of exotic, multiquark hadrons, i.e. mesons which contain additional quarks, beyond the usual quark-antiquark pair and baryons which consist of more than three quarks. In all cases with robust evidence they contain at least one heavy quark Q=c or b, the majority including two heavy quarks. Two key theoretical questions have been triggered by these discoveries: (a) how are quarks organized inside these multiquark states -- as compact objects with all quarks within one confinement volume, interacting via color forces, perhaps with an important role played by diquarks, or as deuteron-like hadronic molecules, bound by light-meson exchange? (b) what other multiquark states should we expect? The two questions are tightly intertwined. Each of the interpretations provides a natural explanation of parts of the data, but neither explains all of the data. It is quite possible that both kinds of structures appear in Nature. It may also be the case that certain states are superpositions of the compact and molecular configurations. This Whitepaper brings together contributions from many leading practitioners in the field, representing a wide spectrum of theoretical interpretations. We discuss the importance of future experimental and phenomenological work, which will lead to better understandingof multiquark phenomena in QCD.

hep-ph↗

arXiv2022

New hadron configuration: The double-gluon hybrid state

This is the first study on the double-gluon hybrid, which consists of one valence quark and one valence antiquark together with two valence gluons. We concentrate on the one with the exotic quantum number $J^{PC} = 2^{+-}$ that conventional $\bar q q$ mesons can not reach. We apply QCD sum rule method to evaluate its mass to be $2.26^{+0.20}_{-0.25}$ GeV, and study its possible decay patterns. Especially, its three-meson decay patterns are generally not suppressed severely compared to two-meson decay patterns, so the $S$-wave three-meson decay channels $f_1ωπ/f_1ρπ$ can be useful in identifying its nature, which is of particular importance to the direct test of QCD in the low energy sector.

hep-ph↗

arXiv2021

Decay properties of the $X(3872)$ through the Fierz rearrangement

We systematically construct all the tetraquark currents of $J^{PC} = 1^{++}$ with the quark configurations $[cq][\bar c \bar q]$, $[\bar c q][\bar q c]$, and $[\bar c c][\bar q q]$ ($q=u/d$). Their relations are derived using the Fierz rearrangement of the Dirac and color indices, through which we study decay properties of the $X(3872)$ under both the compact tetraquark and hadronic molecule interpretations. We propose to search for the $X(3872) \rightarrow χ_{c0} π$, $η_c ππ$, and $χ_{c1} ππ$ decay processes in particle experiments.

hep-ph↗

arXiv2021

Two- and three-gluon glueballs of $C=+$

We study two- and three-gluon glueballs of $C=+$ using the method of QCD sum rules. We systematically construct their interpolating currents, and find that all the spin-1 currents of $C=+$ vanish. This suggests that the ``ground-state'' spin-1 glueballs of $C=+$ do not exist within the relativistic framework. We calculate masses of the two-gluon glueballs with $J^{PC} = 0^{\pm+}/2^{\pm+}$ and the three-gluon glueballs with $J^{PC} = 0^{\pm+}/2^{\pm+}$. We propose to search for the $J^{PC} = 0^{-+}/2^{-\pm}/3^{\pm-}$ three-gluon glueballs in their three-meson decay channels in future BESIII, GlueX, LHC, and PANDA experiments.

hep-ph↗

arXiv2021

$P$-wave charmed baryons of the $SU(3)$ flavor $\mathbf{6}_F$

We use QCD sum rules to study mass spectra of $P$-wave charmed baryons of the $SU(3)$ flavor $\mathbf{6}_F$. We also use light-cone sum rules to study their $S$- and $D$-wave decays into ground-state charmed baryons together with light pseudoscalar and vector mesons. We work within the framework of heavy quark effective theory, and we also consider the mixing effect. Our results can explain many excited charmed baryons as a whole, including the $Σ_c(2800)^0$, $Ξ_c(2923)^0$, $Ξ_c(2939)^0$, $Ξ_{c}(2965)^{0}$, $Ω_c(3000)^0$, $Ω_c(3050)^0$, $Ω_c(3066)^0$, $Ω_c(3090)^0$, and $Ω_c(3119)^0$. Their masses, mass splittings within the same multiplets, and decay properties are extracted for future experimental searches.

hep-ph↗

arXiv2021

Investigation of the stability for fully-heavy $bc\bar{b}\bar{c}$ tetraquark states

We study the existence of fully-heavy hidden-flavor $bc\bar{b}\bar{c}$ tetraquark states with various $J^{PC}=0^{\pm+}, 0^{--},1^{\pm\pm}, 2^{++}$, by using the moment QCD sum rule method augmented by fundamental inequalities. Using the moment sum rule analyses, our calculation shows that the masses for the S-wave positive parity $bc\bar{b}\bar{c}$ tetraquark states are about $12.2-12.4$ GeV in both $[\mathbf{\bar{3}_c}]_{bc}\otimes[\mathbf{3_c}]_{\bar{b}\bar{c}}$ and $[\mathbf{6_c}]_{bc}\otimes[\mathbf{\bar{6}_c}]_{\bar{b}\bar{c}}$ color configuration channels. Except for two $0^{++}$ states, such results are below the thresholds $T_{η_cη_b}/T_{Υψ}$ and $T_{B_cB_c}$, implying that these S-wave positive parity $bc\bar{b}\bar{c}$ tetraquark states are probably stable against the strong interaction. For the P-wave negative parity $bc\bar{b}\bar{c}$ tetraquarks, their masses in the $[\mathbf{\bar{3}_c}]_{bc}\otimes[\mathbf{3_c}]_{\bar{b}\bar{c}}$ channel are around $12.9-13.2$ GeV, while a bit higher in the $[\mathbf{6_c}]_{bc}\otimes[\mathbf{\bar{6}_c}]_{\bar{b}\bar{c}}$ channel. They can decay into the $c\bar c+b\bar b$ and $c\bar b+b\bar c$ final states via the spontaneous dissociation mechanism, including the $J/ψΥ$, $η_cΥ$, $J/ψη_b$, $B_c^+B_c^-$ channels.

hep-ph↗

arXiv2021

Exotic $\bar{D}_s^{()}D^{()}$ molecular states and $sc\bar q\bar c$ tetraquark states with $J^P=0^+, 1^+, 2^+$

We have calculated the mass spectra for the $\bar{D}_s^{(*)}D^{(*)}$ molecular states and $sc\bar q\bar c$ tetraquark states with $J^P=0^+, 1^+, 2^+$. The masses of the axial-vector $\bar{D}_sD^{*}$, $\bar{D}_s^{*}D$ molecular states and $\mathbf{1}_{[sc]} \oplus \mathbf{0}_{[\bar q \bar{c}]}$, $\mathbf{0}_{[sc]} \oplus \mathbf{1}_{[\bar q \bar{c}]}$ tetraquark states are predicted to be around 3.98 GeV, which are in good agreement with the mass of $Z_{cs}(3985)^-$ from BESIII \cite{besiii2020Zcs}. In both the molecular and diquark-antidiquark pictures, our results suggest that there may exist two almost degenerate states, as the strange partners of the $X(3872)$ and $Z_c(3900)$. We propose to carefully examine the $Z_{cs}(3985)$ in future experiments to verify this. One may also search for more hidden-charm four-quark states with strangeness not only in the open-charm $\bar{D}_s^{(*)}D^{(*)}$ channels, but also in the hidden-charm channels $η_c K/K^\ast$, $J/ψK/K^\ast$.

hep-ph↗

arXiv2021

Mass spectra for the $cc\bar{b}\bar{b}$/$bb\bar{c}\bar{c}$ tetraquark states

We have studied the masse spectra for the $cc\bar{b}\bar{b}$/$bb\bar{c}\bar{c}$ tetraquark states with quantum numbers $J^{P}=0^{\pm},1^{\pm}$, and $2^{+}$. We systematically construct the interpolating currents with various spin-parity quantum numbers and calculate their two-point correlation functions in the framework of QCD moment sum rule method. Our calculations show that the masses are about $12.3-12.4$ GeV for the positive parity $cc\bar{b}\bar{b}$ tetraquark ground states with $J^{P}=0^+, 1^+, 2^+$, while $12.8-13.1$ GeV for the negative parity channels with $J^{P}=0^-, 1^-$. The mass predictions for the positive parity $cc\bar{b}\bar{b}$ ground states are lower than the $B_{c}B_{c}$ threshold, implying that these tetraquarks can only decay via weak interaction and thus are expected to be stable and narrow.

hep-ph↗

arXiv2021

Mass spectra of $NΩ$ dibaryons in the $^{3}S_1$ and $^{5}S_2$ channels

We study the mass spectra of the $NΩ$ dibaryons in the $^{3}S_1$ and $^{5}S_2$ channels with $J^{P}=1^{+}$ and $2^{+}$ respectively, by using the method of QCD sum rules. We construct two dibaryon interpolating currents in the molecular picture and calculate their correlation functions and spectral densities up to dimension-16 condensates. Our results indicate that there may exist an $NΩ$ dibaryon bound state in the $^{5}S_2$ channel with a binding energy of about $21\ \mathrm{MeV}$. The masses of the $^{3}S_1$ $NΩ$ dibaryons with $J^{P}=1^{+}$ are predicted to be higher than the $NΩ$ and $ΛΞ$ thresholds, and thus can decay into these final states directly in S-wave. The $NΩ(^{5}S_2)$ dibaryon bound state can decay into the octet-octet final states $ΛΞ$ and $ΣΞ$ in D-wave via the quark rearrangement mechanism. The existence of these $NΩ$ dibaryons may be identified in the relativistic heavy-ion collision experiments in the future.

hep-ph↗

arXiv2021

Establishing the first hidden-charm pentaquark with strangeness

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 $\bar D^* Ξ_c$ 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 $\bar D Ξ_c$ molecular state of $J^P=1/2^-$.

hep-ph↗

arXiv2021

Toward the existence of odderon as a three-gluon bound state

Inspired by the evidence of the odderon exchange recently observed by the D0 and TOTEM Collaborations, a QCD sum rule investigation is performed to study the odderon as a three-gluon bound state. There may exist six lowest-lying three-gluon odderons with the quantum numbers $J^{PC} = 1/2/3^{\pm-}$. We systematically construct their interpolating currents, and calculate their mass spectra. To verify their existence, we propose to search for the spin-3 odderons in their $VVV$ and $VVP$ decay channels directly at LHC, with $V$ and $P$ light vector and pseudoscalar mesons respectively.

hep-ph↗

arXiv2021

Light tetraquark states with the exotic quantum number $J^{PC} = 3^{-+}$

We apply the method of QCD sum rules to study the $s q \bar s \bar q$ tetraquark states with the exotic quantum number $J^{PC} = 3^{-+}$, and extract mass of the lowest-lying state to be $2.33^{+0.19}_{-0.16}$ GeV. To construct the relevant tetraquark currents we need to explicitly add the covariant derivative operator. Our systematical analysis on their relevant interpolating currents indicates that: a) this state well decays into the $P$-wave $ρϕ/ωϕ$ channel but not into the $ρf_2(1525)/ωf_2(1525)/ϕf_2(1270)$ channels, and b) it well decays into the $K^*(892) \bar K_2^*(1430)$ channel but not into the $P$-wave $K^*(892) \bar K^*(892)$ channel.

hep-ph↗

arXiv2020

Identifying the $Ξ_c^0$ baryons observed by LHCb as $P$-wave $Ξ_c^\prime$ baryons

We systematically study mass spectra and decay properties of $P$-wave $Ξ_c^\prime$ baryons of the $SU(3)$ flavor $\mathbf{6}_F$, using the methods of QCD sum rules and light-cone sum rules within the framework of heavy quark effective theory. Our results suggest that the three excited $Ξ_c^0$ baryons recently observed by LHCb can be well explained as $P$-wave $Ξ_c^\prime$ baryons: the $Ξ_c(2923)^0$ and $Ξ_c(2939)^0$ are partner states of $J^P = 1/2^-$ and $3/2^-$ respectively, both of which contain one $λ$-mode orbital excitation; the $Ξ_c(2965)^0$ has $J^P = 3/2^-$, and also contains one $λ$-mode orbital excitation. We propose to search for another $P$-wave $Ξ_c^\prime$ state of $J^P = 5/2^-$ in the $Λ_c K/Ξ_c π$ mass spectral in future experiments. Its mass is about $56^{+30}_{-35}$ MeV larger than the $Ξ_c(2965)^0$, and its width is about $18.1^{+19.7}_{-~8.3}$ MeV.

hep-ph↗

arXiv2020

Decay properties of $P_c$ states through the Fierz rearrangement

We systematically study hidden-charm pentaquark currents with the quark configurations $[\bar c u][u d c]$, $[\bar c d][u u c]$, and $[\bar c c][u u d]$. Some of their relations are derived using the Fierz rearrangement of the Dirac and color indices, and the obtained results are used to study strong decay properties of $P_c$ states as $\bar D^{(*)} Σ_c$ hadronic molecules. We calculate their relative branching ratios for the $J/ψp$, $η_c p$, $χ_{c0} p$, $χ_{c1} p$, $\bar D^{(*)0} Λ_c^+$, $\bar D^{0} Σ_c^{+}$, and $\bar D^{-} Σ_c^{++}$ decay channels. We propose to search for the $P_c(4312)$ in the $η_c p$ channel and the $P_c(4440)/P_c(4457)$ in the $\bar D^{0} Λ_c^+$ channel.

hep-ph↗