DsJ(2860) as the first radial excitation of Ds0*(2317)

A coupled-channel model previously employed to describe the narrow Ds0*(2317) and broad D0*(2400) charmed scalar mesons is generalized so as to include all ground-state pseudoscalar-pseudoscalar and vector-vector two-meson channels. All parameters are chosen fixed at published values, except for the overall coupling constant, which is fine-tuned to reproduce the Ds0*(2317) mass. Thus, the radial excitations Ds0*(2850) and D0*(2740) are predicted, both with a width of about 50 MeV. The former state appears to correspond to the new DsJ(2860) resonance decaying to DK announced by BABAR in the course of this work. Also, the D0*(2400) resonance is roughly reproduced, though perhaps with a somewhat too low central resonance peak.     

夸克模型中的Dsj(2317),Dsj(2460)衰变

用夸克模型结合D_s,D_s^*, 讨论窄共振态D_sj^*(2317),D_sj(2460). 除η－π⁰混合角由D^*_s衰变宽度给出, 所有的参数均取自Godfrey和Isgur的夸克模型. 得到的电磁衰变宽度与实验数据和其他作者的结果相一致. 但是, 与现有的实验结果比较, D_sj^*(2317), D_sj(2460)的π介子衰变宽度要小一个数量级. 我们怀疑简单的手征夸克-π轴矢相互作用的哈密顿量不适合于D_sj^*(2317), D_sj(2460)的强衰变.     

On the decays of d~*(2380) in a constituent chiral quark model

After summarizing the experimental results and present status of the d~*(2380) observed at WASA@COSY,two extreme models for explaining its structure, a compact hexaquark dominated model and a loose ??'-D_(12)π model, are briefly discussed, especially the former. By comparing their results with the corresponding data, the differences of the two models are addressed. As a remedy for the latter model, a mixing model and its result are also quoted for a comparison. It is shown that the compact hexaquark dominated structure might be more promising.However, the mixing model is also a possible structure, and more accurate Γ_(d~*)→NN_π data are needed for confirmation.     

Study of semileptonic decays Bs→Ds1(2536)l(v) and Bs→Ds2(2573)l(v) in the CQM model

Based on the assumption that Ds1 (2536) and Ds2 (2573) belong to T doublet (1+,2+),we calculate the semileptonic decays of Bs to Ds1(2536) and Ds2(2573) in terms of the Constituent Quark Meson (CQM)model.For Bs→Ds1(2536)+l(v) and Bs→Ds2(2573)+l(v),the order of magnitude of the obtained branching ratios is 10-3.Our numerical results of the semileptonic decays of Bs to Ds1(2536) and Ds2(2573) are large,which implies that two semileptonic decays should be seen in future experiments.     

DsJ(2632)强衰变的研究

SELEX合作组发现的D_sJ(2632)引起了很多的讨论, 同时也带来了激烈的争论. 它的自旋宇称还没有最后确定, 如果它真的存在, 它的夸克结构可能是奇特的. 以前有的文献假定D_sJ(2632)是1^－的径向激发态, 我们假定它可能是夸克结构为qq,J^P为2⁺的基态或者0⁺D_sJ(2317)的第一径向激发态, 用Bethe-Salpeter方程重新计算了它的衰变宽度. 计算结果表明, 理论值和实验数据还是存在尖锐的矛盾.     

Decays of Dsj*(2317) and Dsj(2460) Mesons in the Quark Model

We study the decay widths of the narrow resonances D_sj^*(2317) and D_sj(2460) in the chiral quark model, together with the well-known D^* and D_s^* mesons. All the parameters in our calculation are taken from Godfrey and Isgur's quark model except the π⁰－η mixing angle which is fixed by the D_s^* decay widths. The calculated electromagnetic decay widths agree with those from other groups and the experimental data available quite well. However, the pionic decay widths of D_sj(2317) and D_sj(2460) are too small to fit the experimental data. We suspect that the simple chiral quark pion axial-vector interaction Hamiltonian is not suitable for hadron strong decays of D_sj(2317) and D_sj(2460).     

Observation of the psi(4415)-->DD2*(2460) decay using initial-state radiation

We report measurements of the exclusive cross section for e(+)e(-)-->D(0)D(-)pi(+) over the center-of-mass energy range 4.0 GeV to 5.0 GeV with initial-state radiation and the first observation of the decay psi(4415)-->D(0)D(-)pi(+). From a study of the resonant substructure in psi(4415) decay we conclude that the psi(4415)-->D(0)D(-)pi(+) decay is dominated by psi(4415)-->DD(2)(*)(2460). We obtain B(psi(4415)-->D(0)D(-)pi(nonresonant)(+))/B(psi(4415)-->DD(2)(*)(2460)-->D(0)D(-)pi(+))<0.22 at 90% C.L. The analysis is based on a data sample collected with the Belle detector with an integrated luminosity of 673 fb(-1).     

Analysis of the Possible $D\bar{D}_{s0}^*(2317)$ and $D^*\bar{D}_{s1}^*(2460)$ Molecules with QCD Sum Rules *

In this article, we assume that there exist the pseudoscalar $D\bar{D}_{s0}^*(2317)$ and $D^*\bar{D}_{s1}^*(2460)$ molecular states $Z_{1,2}$ and construct the color singlet-singlet molecule-type interpolating currents to study their masses with the QCD sum rules. In calculations, we consider the contributions of the vacuum condensates up to dimension-10 and use the formula $\mu=\sqrt{M_{X/Y/Z}^{2}-(2{\mathbb{M}}_{c})^{2}}$ to determine the energy scales of the QCD spectral densities. The numerical results, $M_{Z_1}=4.61_{-0.08}^{+0.11}\,\text{GeV}$ and $M_{Z_2}=4.60_{-0.06}^{+0.07}\,\text{GeV}$, which lie above the $D\bar{D}_{s0}^*(2317)$ and $D^*\bar{D}_{s1}^*(2460)$ thresholds respectively, indicate that the $D\bar{D}_{s0}^*(2317)$ and $D^*\bar{D}_{s1}^*(2460)$ are difficult to form bound state molecular states, the $Z_{1,2}$ are probably resonance states.     

Bounds on the CP asymmetry in like-sign dileptons from B(0)B*(0) meson decays

We have measured the charge asymmetry in like-sign dilepton yields from B(0)B*(0) meson decays using the CLEO detector at the Cornell Electron Storage Ring. We find a(0)(ll) identical with[N(l(+)l(+))-N(l(-)l(-))]/[N(l(+)l(+))+N(l(-)l(-))] = +0.013+/-0.050+/-0.005. We combine this result with a previous, independent measurement and obtain Re(epsilon(B))/(1+ the absolute value of epsilon(B)(2)) = +0.0035+/-0.0103+/-0.0015 (uncertainties are statistical and systematic, respectively) for the CP impurity parameter, epsilon(B).     

Study of B<Subscript>s</Subscript>→D<Subscript>sJ</Subscript>(2317,2460)lν̄ semileptonic decays in the CQM model

Assuming D^* _sJ(2317) and D_sJ(2460) to be the (0⁺,1⁺) chiral partners of the regular particles D_s(1968) and D^* _s(2112), we calculate the semileptonic decays of B_s to D_s(1968), D^* _s(2112), D_sJ ^*(2317) and D_sJ(2460) in terms of the constituent quark meson model. The large branching ratios of the semileptonic decays of B_s to D_sJ ^*(2317) and D_sJ(2460) indicate that these two semileptonic decays should be seen in future experiments. PACS 12.25.Ft; 12.38.Lg; 12.39.Fe; 12.39.Hg     

Study of K*(892) mass and width splitting caused by model difference

According to the new K*(892)0 and K*(892)- masses reported by the BELLE experiment and the K*(892)0 mass reported by the FOCUS experiment, mass splitting between neutral and charged K*(892) becomes very small. This is significantly different from the current world average values given by the Particle Data Group 2008. We find that there are differences between models used to fit the K*(892) decay invariant mass spectra in different measurements and study the model dependence in the measurement of K*(892) parameters. We refit the K*(892)0 mass spectra of the BELLE and FOCUS experiments with the formula used by BELLE in fitting K*(892)- to get new mass and width. After refitting, the K*(892)0 mass of the BELLE experiment becomes 1.4 MeV/c2 larger than the initial value and that of the FOCUS experiment is 1 MeV/c2 smaller than the initial value. We also fit the spectra of some other experiments to extract the K*(892) parameters using the BELLE K* (892)- parametrization.     

Understanding the structure of d~*(2380) in chiral quark model

The structure and decay properties of d~* have been detailedly investigated in both the chiral SU(3) quark model and the extended chiral SU(3) quark model that describe the energies of baryon ground states and the nucleon-nucleon(NN) scattering data satisfactorily. By performing a dynamical coupled-channels study of the system of ?? and hidden-color channel(CC) with quantum numbers I(J~P) = 0(3~+) in the framework of the resonating group method(RGM), we find that the d~* has a mass of about 2.38-2.42 Ge V and a root-mean-square radius(RMS) of about 0.76-0.88 fm. The channel wave function is extracted by a projection of the RGM wave function onto the physical basis, and the fraction of CC component in the d~* is found to be about 66%-68%, which indicates that the d~* is a hexaquark-dominated exotic state. Based on this scenario the partial decay widths of d~*→dπ~0π~0and d~*→dπ~+π~- are further explicitly evaluated and the total width is then obtained by use of the branching ratios extracted from the measured cross sections of other possible decay channels. Both the mass and the decay width of d~* calculated in this work are compatible with the data(M≈2380 Me V, Γ≈70 Me V) reported by WASA-at-COSY Collaboration.     

Observation of a new DsJ meson in B+-->D0D0K+ decays

We report the observation of a new DsJ meson produced in B+-->D0DsJ-->D0D0K+. This state has a mass of M=2708+/-9(-10)(+11) MeV/c2, a width Gamma=108+/-23(-31)(+36) MeV/c2 and a 1- spin-parity. The statistical significance of this observation is 8.4 sigma. The results are based on an analysis of 449 x 10(6) BB events collected at the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+e- collider.     

Systematic analysis of D_J(2580), D_J~*(2650), D_J(2740), D_J~*(2760),D_J(3000) and D_J~*(3000) in the D meson family

In this work, we tentatively assign the charmed mesons D J(2580), D*J(2650), D J(2740), D*J(2760),D J(3000) and D*J(3000) observed by the LHCb collaboration according to their spin, parity and masses, then systematically study their strong decays to ground state charmed mesons plus pseudoscalar mesons with the3P0 decay model. Based on these studies, we assign the D*J(2760) as the 1D5/23-state, the D*J(3000) as the 1F5/22+or 1F7/24+state, the D J(3000) as the 1F7/23+or 2P1/21+state in the D meson family. As a byproduct, we also study the strong decays of the states 2P1/20+, 2P3/22+, 3S1/21-, 3S1/20-etc, which will be valuable in searching for the partners of these D mesons.     

Strong decays of <Emphasis Type="Italic">N</Emphasis>*(1535) in an extended chiral quark model

The strong decays of the N*(1535) resonance are investigated in an extended chiral quark model by including the low-lying qqqqq components in addition to the qqq component.The results show that these five-quark components in N*(1535) contribute significantly to the N*(1535)→ Nπ and N*(1535) → Nη decays.The contributions to the Nη decay come from both the lowest energy and the next-to-lowest energy five-quarks components,while the contributions to the Nπ decay come from only the latter one.Taking these contr...     

Contact terms in E.M. decays of mesons

The ratios R_J(P)Γ(J)→P⁺P^?), P = π or K, have been evaluated ad due to contact interactions genrated by gauge invariance, for mesons with natural J^P. R_J increases rapidly with J. This provides unambigous tests for the model and indicates that contact terms are prolific sources of photons and leptons in hadron collisions.