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Register a new userStrong decays of fully-charm tetraquarks into di-charmonia
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We study strong decays of the possible fully-charm tetraquarks recently observed by LHCb, and calculate their relative branching ratios through the Fierz rearrangement. Together with our previous QCD sum rule study [Phys. Lett. B 773, 247 (2017)], our results suggest that the broad structure around $6.2$-$6.8$ GeV can be interpreted as an $S$-wave $ccbar c bar c$ tetraquark state with $J^{PC} = 0^{++}$ or $2^{++}$, and the narrow structure around 6.9 GeV can be interpreted as a $P$-wave one with $J^{PC} = 0^{-+}$ or $1^{-+}$. These structures were observed in the di-$J/psi$ invariant mass spectrum, and we propose to confirm them in the di-$eta_c$, $J/psi h_c$, $eta_c chi_{c0}$, and $eta_c chi_{c1}$ channels. We also propose to search for their partner states having the negative charge-conjugation parity in the $J/psi eta_c$, $J/psi chi_{c0}$, $J/psi chi_{c1}$, and $eta_c h_c$ channels.
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With the spin rearrangement, we have performed a comprehensive investigation of the decay patterns of the S-wave tetraquarks and P-wave tetraquarks where the P-wave excitation exists either between the diquark and anti-diquark pair or inside the diquark. Especially, we compare the decay patterns of $Y(4260)$ with different inner structures such as the conventional charmonium, the molecule, the P-wave tetraquark and the hybrid charmonium. We notice the $J/psi pipi$ mode is suppressed in the heavy quark symmetry limit if $Y(4260)$ is a molecular state. Moreover the hybrid charmonium and hidden-charm tetraquark have very similar decay patterns. Both of them decay into the $J/psi pipi$ and open charm modes easily. We also discuss the decay patterns of $X(3872)$, $Y(4360)$, and several charged states such as $Z_c(4020)$. The $h_cpi^{pm}$ decay mode disfavors the tetraquark assumption of $Z_c(4020)$.
The open-charm strong decays of higher charmonium states up to the mass of the $6P$ multiplet are systematically studied in the $^3P_0$ model. The wave functions of the initial charmonium states are calculated in the linear potential (LP) and screened potential (SP) quark model. The decay widths for most of the well-established charmonium states above the open-charm thresholds can be reasonably described. By comparing our quark model calculations with the experimental observations we also discuss the nature of some of the newly observed charmonium-like states. It is found that (i) the $psi(4415)$ may favor the $psi(4S)$ or $psi_1(3D)$ assignment. There may exist two highly overlapping vector charmonium states around 4.4 GeV; (ii) In the LP model the $J^{PC}=1^{--}$ $Y(4660)$ resonance and the $J^{PC}=0^{++}$ $X(4500)$ resonance may be assigned as the $psi(5S)$ and $chi_{c0}(4P)$, respectively; (iii) The newly observed state $X^*(3860)$ can be assigned as the $chi_{c0}(2P)$ state with a narrow width of about $30$ MeV; (iv) It seems to be difficult to accommodate the $X(4140)$ and $X(4274)$ states in the same potential model as excited $chi_{c1}$ states. (v) The $X(3940)$ resonance can be assigned as the $eta_c(3S)$ state; (vi) The vector charmonium-like states $Y(4230/4260,4360)$ and scalar $X(4700)$ cannot be described by any conventional charmonium states self-consistently in our model.
The recent observation by the D0 collaboration of a narrow structure X(5568) consisting of four different quark flavors bdus, has not been confirmed by LHCb. More data and dedicated analyses are needed to cover a larger mass range. In the tightly bound diquark model, we estimate the lightest bdus, 0^+ tetraquark at a mass of about 5770 MeV, approximately 200 MeV above the reported X(5568), and just 7 MeV below the B Kbar threshold. The charged tetraquark is accompanied by I=1 and I=0 neutral partners almost degenerate in mass. A bdus, S-wave, 1^+ quartet at 5820 MeV is implied as well. In the charm sector, cdus, 0^+ and 1^+ tetraquarks are predicted at 2365 MeV and 2501 MeV, about 40-50 MeV heavier than D_{s0}(2317) and D_{s1}(2460). bdus tetraquarks can be searched in the hadronic debris of a jet initiated by a b. However, some of them may also be produced in B_c decays. The proposed discovery modes of S-wave tetraquarks are B_c --> X_{b0} + pi with the subsequent decays X_{b0} --> B_s + pi, giving rise to final states such as B_s pi^+ pi^0. We also emphasize the importance of B_c decays as a source of bound hidden charm tetraquarks, such as B_c --> X(3872) + pi.
We perform a SU(3) analysis for both semi-leptonic and non-leptonic heavy meson weak decays into a pseudoscalar meson and a fully-light tetraquark in 10 or 27 representation. A reduction of the SU(3) representation tensor for the fully-light tetraquarks is produced and all the flavor components for each representation tensor are listed. The decay channels we analysis include $B/D to U/T~P~l u$, $B/D to U/T~P $ and $B_c to U/T~P/D$, with $U/T$ represents a fully-light tetraquark in 10 or 27 representation and $P$ is a pseudoscalar meson. Finally, among these results we list all the golden decay channels which are expected to have more possibilities to be observed in experiments.
In this work, we systematically study the mass spectrum of the fully heavy tetraquark in an extended chromomagnetic model, which includes both color and chromomagnetic interactions. Numerical results indicate that the energy level is mainly determined by the color interaction, which favors the color-sextet $ket{(QQ)^{6_{c}}(bar{Q}bar{Q})^{bar{6}_{c}}}$ configuration over the color-triplet $ket{(QQ)^{bar{3}_{c}}(bar{Q}bar{Q})^{3_{c}}}$ one. The chromomagnetic interaction mixes the two color configurations and gives small splitting. The ground state is always dominated by the color-sextet configuration. We find no stable state below the lowest heavy quarkonium pair thresholds. Most states may be wide since they have at least one $S$-wave decay channel into two $S$-wave mesons. One possible narrow state is the $1^{+}$ $bbbar{b}bar{c}$ state with a mass $15719.1~text{MeV}$. It is just above the $eta_{b}bar{B}_{c}$ threshold. But this channel is forbidden because of the conservation of the angular momentum and parity.
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