Searcharxiv⌕ Search

arXiv subjects

Shi-Lin Zhu

Publications and source records attributed to Shi-Lin Zhu.

At least 235 records · Page 13Linked to original sources

The Strong Decay Patterns of the $1^{-+}$ Exotic Hybrid Mesons

We calculate the coupling constants of the decay modes $1^{-+}\rightarrowρπ, f_1π, b_1π, ηπ, η'π, a_1π, f_1η$ within the framework of the light-cone QCD sum rule. Then we calculate the partial width of these decay channels, which differ greatly from the existing calculations using phenomenological models. For the isovector $1^{-+}$ state, the dominant decay modes are $ρπ, f_1π$. For its isoscalar partner, its dominant decay mode is $a_1π$. We also discuss the possible search of the $1^{-+}$ state at BESIII, for example through the decay chains $J/ψ(ψ')\to π_1 +γ$ or $J/ψ(ψ')\to π_1 +ρ$ where $π_1$ can be reconstructed through the decay modes $π_1\to ρπ\to π^+π^-π^0$ or $π_1\to f_1(1285)π^0$. Hopefully the present work will be helpful to the experimental establishment of the $1^{-+}$ hybrid meson.

hep-ph↗

$D\bar{D}$ production and their interactions

S and P wave $D\bar{D}$ scatterings are studied in a meson exchange model with the coupling constants obtained in the heavy quark effective theory. With the extracted P wave phase shifts and the separable potential approximation, we include the $D\bar{D}$ rescattering effect and investigate the production process $e^+e^-\to D\bar{D}$. We find that it is difficult to explain the anomalous line shape observed by the BES collaboration with this mechanism. Combining our model calculation and the experimental measurement, we estimate the upper limit of the nearly universal cutoff parameter to be 1.7 GeV. With this number, the upper limits of the binding energies of the S wave $D\bar{D}$ and $B\bar{B}$ bound states are obtained. Assuming that the S wave and P wave interactions rely on the same cutoff, our study provides a way of extracting the information about S wave molecular bound states from the P wave meson pair production.

hep-ph↗

Light Scalar Meson sigma(600) in QCD Sum Rule with Continuum

The light scalar meson sigma(600) is known to appear at low excitation energy with very large width on top of continuum states. We investigate it in the QCD sum rule as an example of resonance structures appearing above the corresponding thresholds. We use all the possible local tetraquark currents by taking linear combinations of five independent local ones. We ought to consider the pi-pi continuum contribution in the phenomenological side of the QCD sum rule in order to obtain a good sum rule signal. We study the stability of the extracted mass against the Borel mass and the threshold value and find the sigma(600) mass at 530 MeV +- 40 MeV. In addition we find the extracted mass has an increasing tendency with the Borel mass, which is interpreted as caused by the width of the resonance.

hep-ph↗

Possible heavy molecular states composed of a pair of excited charm-strange mesons

The P-wave charm-strange mesons $D_{s0}(2317)$ and $D_{s1}(2460)$ lie below the $DK$ and $D^\ast K$ threshold respectively. They are extremely narrow because their strong decays violate the isospin symmetry. We study the possible heavy molecular states composed of a pair of excited charm strange mesons. As a byproduct, we also present the numerical results for the bottonium-like analogue.

hep-ph↗

Possible $J^{PC} = 0^{--}$ Charmonium-like State

We study the possible charmonium-like states with $J^{PC}=0^{--}, 0^{-+}$ using the tetraquark interpolating currents with the QCD sum rules approach. The extracted masses are around 4.5 GeV for the $0^{--}$ charmonium-like states and 4.6 GeV for the $0^{-+}$ charmonium-like states while their bottomonium-like analogues lie around 10.6 GeV. We also discuss the possible decay, production and the experiment search of the $0^{--}$ charmonium-like state.

hep-ph↗

The molecular systems composed of the charmed mesons in the $H\bar{S}+h.c.$ doublet

We study the possible heavy molecular states composed of a pair of charm mesons in the H and S doublets. Since the P-wave charm-strange mesons $D_{s0}(2317)$ and $D_{s1}(2460)$ are extremely narrow, the future experimental observation of the possible heavy molecular states composed of $D_s/D_s^\ast$ and $D_{s0}(2317)/D_{s1}(2460)$ may be feasible if they really exist. Especially the possible $J^{PC}=1^{--}$ states may be searched for via the initial state radiation technique.

hep-ph↗

Strong and Electromagnetic Decays of The $D$-wave Heavy Mesons

We calculate the $π$, $ρ$, $ω$, and $γ$ coupling constants between the heavy meson doublets $(1^-,2^-)$ and (0^-,1^-)/(0^+,1^+) within the framework of the light-cone QCD sum rule at the leading order of heavy quark effective theory. Most of the sum rules are stable with the variations of the Borel parameter and the continuum threshold. Then we calculate the strong and electromagnetic decay widths of the $(1^-,2^-)$ D-wave heavy mesons. Their total widths are around several tens of MeV, which is helpful in the future experimental search.

hep-ph↗

Light vector meson and heavy baryon strong interaction

We calculate the coupling constants between the light vector mesons and heavy baryons within the framework of the light-cone QCD sum rule in the leading order of heavy quark effective theory. Most resulting sum rules are stable with the variations of the Borel parameter and the continuum threshold. The extracted couplings will be useful in the study of the possible heavy baryon molecular states.

hep-ph↗

The Possible J^{PC}=0^{--} Exotic State

In order to explore the possible existence of the exotic $0^{--}$ state, we have constructed the tetraquark interpolating operators systematically. As a byproduct, we notice the $0^{+-}$ tetraquark operators without derivatives do not exist. The special Lorentz structure of the $0^{--}$ currents forbids the four-quark correction to the spectral density. Now the gluon condensate is the dominant power correction. Within the framework of the finite energy sum rule, none of the seven interpolating currents supports a resonant signal. Therefore we conclude that the exotic $0^{--}$ state does not exist below 2 GeV, which is consistent with the current experimental observations.

hep-ph↗

The Vector Meson And Heavy Meson Strong Interaction

We calculate the coupling constants between the light vector mesons and heavy mesons within the framework of the light-cone QCD sum rule in the leading order of heavy quark effective theory. The sum rules are very stable with the variations of the Borel parameter and the continuum threshold. The extracted couplings will be useful in the study of the possible heavy meson molecular states. They may also helpful in the interpretation of the proximity of X(3872), Y(4260) and Z(4430) to the threshold of two charmed mesons through the couple-channel mechanism.

hep-ph↗

Light Pseudoscalar Meson and Heavy Meson Scattering Lengths

We have performed a systematical calculation of the pion ($π, K, η$) and heavy pseudoscalar meson S-wave scattering lengths up to ${\cal O}(p^3)$ in the chiral perturbation theory in the heavy quark symmetry limit. With the three scattering lengths from the lattice simulations as input we estimate the unknown low-energy constants. Then we predict all the other unmeasured scattering lengths. The analytical expressions and predictions may be helpful to future investigations. Especially we note that the DK scattering length is positive. Therefore their interaction is attractive, which helps to lower the mass of the "bare" charm-strange scalar state in the quark model through the couple-channel effect.

hep-ph↗

Large $N_c$ Expansion and the Parity Violating $π, N, Δ$ Couplings

In the limit of large $N_c$ we first consider the $N_c$ ordering of the various parity violating $π, N, Δ$ couplings. Then we derive the relations among these couplings and consistency relations from the stability of these couplings under the chiral loop corrections with and without the mass splitting between $N$ and $Δ$. Especially we find that $h_Δ=-{3\over \sqrt{5}}h_π$ in the large $N_c$ limit, which correctly reproduces the relative sign and magnitude of the "DDH" values for these PV couplings.

hep-ph↗

Y(4143) is probably a molecular partner of Y(3930)

After discussing the various possible interpretations of the Y(4143) signal observed by the CDF collaboration in the $J/ψϕ$ mode, we tend to conclude that Y(4143) is probably a $D_s^\ast {\bar D}_s^\ast$ molecular state with $J^{PC}=0^{++}$ or $2^{++}$ while Y(3930) is its $D^\ast {\bar D}^\ast$ molecular partner as predicted in our previous work (arXiv:0808.0073). Both the hidden-charm and open charm two-body decays occur through the rescattering of the vector components within the molecular states while the three- and four-body open charm decay modes are forbidden kinematically. Hence their widths are narrow naturally. CDF, Babar and Belle collaborations may have discovered heavy molecular states already. We urge experimentalists to measure their quantum numbers and explore their radiative decay modes in the future.

hep-ph↗

Semileptonic decays of $B_{s1}$, $B_{s2}^*$, $B_{s0}$ and $B_{s1}'$

Stimulated by recent observations of the excited bottom-strange mesons $B_{s1}$ and $B_{s2}^*$, we calculate the semileptonic decays $B_{s0}, B_{s1}^{\prime}, B_{s1}, B_{s2}^*\to [D_s(1968), D_{s}^*(2112), D_{sJ}(2317), D_{sJ}(2460)]\ell\barν$, which is relevant for the exploration of the potential of searching these semileptonic decays in experiment.

hep-ph↗

The I^G J^{PC}=0^+ 1^{-+} Tetraquark State

We study the tetraquark state with I^G J^{PC} = 0^+ 1^{-+} in the QCD sum rule. We exhaust all possible flavor structures by using a diquark-antidiquark construction and find that the flavor structure 3*6+6*3 is preferred. There are altogether four independent currents which have the quark contents q s \bar q \bar s. By using both the Shifman-Vainshtein-Zakharov (SVZ) sum rule and the finite energy sum rule, these currents lead to mass estimates around 1.8 - 2.1 GeV, where the uncertainty is due to the mixing of two single currents. Its possible decay modes are S-wave b_1(1235) ηand b_1(1235) η^\prime, and P-wave KK, ηη, ηη^\prime and η^\prime η^\prime, etc. The decay width is around 150 MeV through a rough estimation.

hep-ph↗

Scalar Tetraquark Currents With Application to the QCD Sum Rule

We study the light scalar mesons in the QCD sum rule. We construct both the diquark-antidiquark currents $(qq)(\bar q \bar q)$ and the meson-meson currents $(\bar qq)(\bar qq)$. We find that there are five independent currents for both cases, and derive the relations between them. For the meson-meson currents, five independent currents are formed by products of color singlet $\bar q q$ pairs or color octet pairs. However, they can be related to each other, and the relations are derived. We obtain the masses of the light scalar mesons which are consistent with the experiments.

hep-ph↗

The Δcontribution to the parity-violating nucleon-nucleon force

Because the nucleon may be excited and transformed into a virtual $Δ$ resonance easily, we consider the decuplet contribution to the parity-violating (PV) nucleon-nucleon interaction in the chiral effective field theory. The effective PV nucleon-nucleon potential is derived without introducing any unknown coupling constants.

nucl-th↗

X(3872) and Other Possible Heavy Molecular States

We perform a systematic study of the possible molecular states composed of a pair of heavy mesons such as $D\bar D$, $D^\ast\bar D$, $D^\ast \bar D^\ast$ in the framework of the meson exchange model. The exchanged mesons include the pseudoscalar, scalar and vector mesons. Through our investigation, we find that (1) the structure X(3764) is not a molecular state; (2) There exists strong attraction in the range $r < 1$ fm for the $D^*\bar D^*$ system with $J=0, 1$. If future experiments confirm $Z^+(4051)$ as a loosely bound molecular state, its quantum number is probably $J^{P}=0^+$. Its partner state $Φ^{**0}$ may be searched for in the $π^0χ_{c1}$ channel; (3) The vector meson exchange provides strong attraction in the $D^\ast \bar D$ channel together with the pion exchange. A bound state solution exists with a reasonable cutoff parameter $Λ\sim 1.4$ GeV. X(3872) may be accommodated as a molecular state dynamically although drawing a very definite conclusion needs further investigation; (4) The $B^\ast \bar B$ molecular state exists.

hep-ph↗