Dynamical study of the possible molecular state X（3872） with the s-channel one gluon exchange interaction

The recently observed X（3872） resonance, which is difficult to assign a conventional cc charmonium state in the quark model, may be interpreted as a molecular state. Such a molecular state is a hidden flavor four quark state because of its charmonium-like quantum numbers. The s-channel one gluon exchange is an interaction which only acts in the hidden flavor multi-quark system. In this paper, we will study the X（3872） and other similiar hidden flavor molecular states in a quark model by taking into account the s-channel one gluon exchange interaction.     

Analysis of the decay B^0→Xc1π^0 with light-cone QCD sum rules

In this article, we calculate the contribution from the nonfactorizable soft hadronic matrix element to the decay B^0→Xc1π^0 with the light-cone quantum chromo-dynamic （QCD） sum rules. The numerical results show that its contribution is rather large and should not be neglected. The total amplitudes lead to a branching fraction which is in agreement with the experimental data marginally.     

Dynamical study of the possible molecular state X(3872) with the s-channel one gluon exchange interaction

The recently observed X(3872) resonance, which is difficult to assign a conventional c charmonium state in the quark model, may be interpreted as a molecular state. Such a molecular state is a hidden flavor four quark state because of its charmonium-like quantum numbers. The s-channel one gluon exchange is an interaction which only acts in the hidden flavor multi-quark system. In this paper, we will study the X(3872) and other similiar hidden flavor molecular states in a quark model by taking into account the s-channel one gluon exchange interaction.     

Charmed-Hadron Production in Υ(1S) Semi-inclusive Decay

In the framework of the NRQCD factorization formalism,we calculate the decay rate for the process Υ(1 S) → ccgg to the next-to-leading order(NLO) in the relative velocity v of the b quark in the bottomonium rest frame.We also study the momentum distributions of the charm quark and the charmed-hadron in the decay.The momentum distribution of the charmed-hadron is obtained by convolving the charm quark momentum distribution with a fragmentation function of the charm quark into the hadron.In addition,we fit the nonperturbative NRQCD matrix element v 2 Υ through comparing the theoretical prediction with the measurement from the BaBar collaboration for the decay rate of Υ(1 S) → D + X.In return,taking this matrix element as an input parameter,we predict the decay rates as well as the momentum distributions for a collection of charmed-hadrons in the process Υ(1S) → ccgg → hX.     

QCD Sum Rules Study of X（4350）

The QCD sum rule approach is used to analyze the nature of the recently observed new resonance X （4350）, which is assumed to be a diquark-antidiquark state [cs][cs] with jPC = 1-＋. The interpolating current representing this state is proposed. In the calculation, contributions of operators up to dimension six are included in the operator product expansion （OPE）, as well as terms which are linear in the strange quark mass ms. We find ml-＋ = （4.82 ~ 0.19） GeV, which is not compatible with the X（4350） structure as a 1-＋ tetraquark state. Finally, we also discuss the difference of a four-quark state＇s mass whether the state＇s interpolating current has a definite charge conjugation.     

Can X(5568) be a tetraquark state?

Very recently, the D0 collaboration has reported the observation of a narrow structure, X(5568), in the decay process X(5568)→ B_s~0π±using the 10.4fb~(-1) data of pp collision at 8~(1/2) = 1.96 TeV. This structure is of great interest since it is the first hadronic state with four different valence quark flavors, b, s, u, d. In this work,we investigate tetraquarks with four different quark flavors. Based on the diquark-antidiquark scheme, we study the spectroscopy of the tetraquarks with one heavy bottom/charm quark and three light quarks. We find that the lowest-lying S-wave state, a tetraquark with the flavor [su][bd] and the spin-parity JP= 0~+, is about 150 MeV higher than the X(5568). Further detailed experimental and theoretical studies of the spectrum, production and decays of tetraquark states with four different flavors are vital to gain a better understanding of the nature and classification of hadron exotic states.     

Chiral SU（3） Quark Model Study of Tetraquark States： cnn^-s^-/css^-s^-

The new members of the charm-strange family Dsj^＊（2317）, Dsj（2460）, and Ds（2632）, which have the surprising properties, are challenging the present models. Many theoretical interpretations have been devoted to this issue. Most authors suggest that they are not the conventional cs^- quark model states, but possibly are four-quark states, molecule states, or mixtures of a P-wave cs^- and a four-quark state. In this work, we follow the four-quark-state picture, and study the masses of cnn^-s^-/css^-s^- states （n is u or d quark） in the chiral SU（3） quark model. The numerical results show that the mass of the mixed four-quark state （cnn^-s^-/css^-s^-） with spin parity j^P ： 0^＋ might not be Ds （2632）. At the same time, we also conclude that Dsj^＊（2317） and Dsj（2460） cannot be explained as the pure four-quark state.     

Analysis of the decay B0→χclπ0 with light-cone QCD sum rules

In this article,we calculate the contribution from the nonfactorizable soft hadronic matrix element to the decay B~0→χc1~π~0 with the light-cone quantum chromo-dynamic(QCD) sum rules.The numerical results show that its contribution is rather large and should not be neglected.The total amplitudes lead to a branching fraction which is in agreement with the experimental data marginally.     

Probing the mass degeneracy of particles with different spins

The spin is an important property of a particle. Although it is unlikely, there is still a possibility that two particles with di erent spins share similar masses. In this paper, we propose a method to probe this kind of mass degeneracy of particles with di erent spins. We use the cascade decay B⁺→X(3872)K⁺, X(3872)→D⁺D^- to illustrate our method. It can be seen that the possible mass degeneracy of X(3872) can lead to interesting behavior in the corresponding cascade decay.     

Controlled Teleportation Using Four-Particle Cluster State

A controlled teleportation scheme is presented. In this scheme, quantum information of a single-qubit state or an entangled two-qubits state is transmitted from a sender （Alice） to a receiver （Charlie） via a four-particle cluster state under the control of the supervisor （Bob）. The feature of this scheme is that the teleportation between the sender and the receiver depends on the control of the supervisor.     

Mass of X(3872) in Bethe–Salpeter Equation for Quarks

From Bethe–Salpeter equation, we deduce the equation which describes the two-body system consisting of a scalar meson and a vector meson. This equation is applied to investigate the exotic narrow state X(3872) assumed as a molecule state composed of D⁰D^*0. The contribution of the resonance D^-0 is the attractive interaction between two heavy mesons in this molecule state. The calculated mass of X is consistent with the experimental data.     

QQqq Four-Quark Bound States in Chiral SU(3) Quark Model

The possibility of QQqq heavy-light four-quark bound states has been analyzed by means of the chiral SU(3) quark model, where Q is the heavy quark (c or b) and q is the light quark (u, d, or s). We obtain a bound state for the bbnn configuration with quantum number J^P=1⁺,I=0 and for the ccnn (J^P=1⁺,I=0) configuration, which is not bound but slightly above the D^*D^* threshold (n is u or d quark). Meanwhile, we also conclude that a weakly bound state in bbnn system can also be found without considering the chiral quark interactions between the two light quarks, yet its binding energy is weaker than that with the chiral quark interactions.     

Can X(3872) be a JP=2- Tetraquark State?

In this article, we test the nature of X(3872), which is assumed to be a P-wave [cq]-scalar-diquark [cq]-axial-vector-antidiquark tetraquark state with J^P=2^-. The interpolating current representing the J^P=2^- state is proposed. Technically, contributions of the operators up to dimension six are included in the operator product expansion. The mass obtained for such state is m_2-=(4.38? 0.15) GeV. We conclude that it is impossible to describe the X(3872) structure as J^P=2^- tetraquark state.     

Production Rate of Ds+Ds- at φ(4030)

By using a generalized relativistic quark pair creation model (QPCM), the hadronic decay processes of φ(4030), assigned as the 3S state of cc, are investigated. The relative rates of φ(4030) → DD, DD^*+DD^*, D^*D^*,and in particular D_s⁺D_s^- are calculated and compared with data. The nodes of the radially excited wavefunctions of charmonium states are found to be significant for these decay processes. Considering the SU(3) suppression factor of ~3 for the s quark pair creation relative to the u and d quarks, we obtain σ(e⁺e^- → φ4(4030) → D_s⁺D_s^-) ~ 0.9 nb.     

Quasi Three-Body Decay of D Meson

The aim of this work is to provide a phenomenological analysis of the contribution of D~0 meson to K*(892)~0π~+π~-(K*(892)~0-→π~+K~-), K~-π~+ω(ω-→π~+π~-π~0) and K~-π~+?(?(1020)-→ K~+K~-) quasi-three-body decays. The analysis of mentioned multi-body decays is such as to factorize into the three-body decay and several channels observed. Hadronic three-body decays receive both resonant and non-resonant contribution. Based on the factorization method, there are tree and emission annihilation diagrams for these decay modes. In the case of D~0 to vector pseudoscalar states appeared in factored terms, the matrix elements of the vector and axial vector currents between the D~0 and PV mesons can be computed by using D~(*+)pole. Considering the non-resonant and resonant amplitude in our computation,the theoretical values of the branching ratio are(9.78 ± 0.46) × 10~(-3),(2.74 ± 0.17) × 10~(-2), and(3.53 ± 0.23) × 10~(-5), while the experimental results of them are(9.9 ±2.3) × 10~(-3),(2.7 ± 0.5) × 10~(-2), and(4 ± 1.7) × 10~(-5) respectively. Comparing computational analysis values with experimental values show that our results are in approximately agreement with them.     

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 conduct a search for the X(3872) → χ_c0π, η_cππ, and χ_c1ππ decay processes in particle experiments.     

Study on Production of Exotic 0^＋ Meson D＇^＊aj（2317） in Decays of ψ（4415）

The newly observed D^＊aj family containing D^＊aj（2317）, Daj（2460）, and Daj（2632） attracts great interests. Determining their structures may be an important task for both theorists and experimentalists. In this work we use a non-relativistic model （the harmonic oscillator model） to evaluate the production rate of D^＊aj （2317） from the decays of ψ（4415）. For a comparison, we a/so employ the widely adopted heavy quark effective theory to repeat the calculation. We lind that the rate is sizable and may be observed at BES III and CLEO, if it is a p-wave excited state of Da（1968）. Unfortunately, the other two members of the family cannot be observed through decays of charmonia, because of the constraints from the final state phase space.     

BESIII 实验对奇特态 X(3872) 的研究

量子色动力学允许超出夸克模型中重子和介子的奇特态的存在。对奇特态的研究是当前高能物理实验的热门话题之一。X(3872)是第一个被实验上观测到的奇特态候选者。实验和理论上对X(3872)的研究从未间断,这使得X(3872)成为了解最好的奇特态。运行在北京正负电子对撞机(BEPCII)上的北京谱仪(BESIII)实验积累了大量的质心能量从3.87 到 4.70 GeV的正负电子对撞数据样本。利用这些数据样本,得到了很多关于X(3872)的实验结果。本文将回顾BESIII上关于X(3872)所取得一系列成果及最新实验进展。对X(3872)等奇特态的研究,将有利于我们对自然界的基本相互作用的理解,也将促进标准模型理论的完善。