On the mass of the ss^- member of the 1^3D1 meson nonet

In the framework of Regge phenomenology and meson meson mixing, this paper estimates the mass of isoscalar state （ss^-） of the 1^3D1 meson nonet, and the results given by two different approaches are 1735.51 ± 59MeV and 1730.29 ±46.SMeV.     

对31S0介子九重态中ss成员的质量分析

利用雷吉轨迹理论和介子九重态质量混合公式两种方案，对3^１Ｓ_０介子九重态中同位旋标量态(主要是ss—成分)的质量给出预言，两种方案分别给出1853MeV和1849±1.2MeV.两种方案自洽的结果，将为实验上寻找该态的候选者提供帮助. 关键词： 雷吉轨迹 介子混合 同位旋标量态     

1S0 and 3S13D1 nucleon-nucleon potentials in the quark compound bag model

For nucleons interacting via formation of the quark compound bag the resulting potential is written in a general form. Explicit examples of potentials are constructed in the ¹S₀, ³S₁ and ³S₁-³D₁ states fitted to the experimental data at T_L ? 1 GeV. As an outcome the QCB energy levels (dibaryons) and NN admixture in QCB are obtained in good agreement with theoretical predictions.     

Continuum bound states K L, D 1(2420), D s1(2536), and their partners K S, D 1(2400), D * sJ(2463)

The very recently observed D^*_sJ(2463) meson is described as a bound state in a unitarised meson model, owing its existence to the strong OZI-allowed coupling to the nearby S-wave threshold. By the same non-perturbative mechanism, the narrow axial-vector D_s1(2536) resonance shows up as a quasi-bound-state partner embedded in the continuum. With the same model and parameters, it is also shown that the preliminary broad 1 ⁺ D₁(2400) resonance and the established narrow 1 ⁺ D₁(2420) may be similar partners, as a result of the strong OZI-allowed coupling to the nearby S-wave threshold. The continuum bound states D₁(2420) and D_s1(2536) are found to be mixtures of 33% and 67% , whereas their partners D₁(2400) and D^*_sJ(2463) have more or less the opposite -state content, but additionally with some or admixture, respectively. The employed mechanism also reproduces the ratio of the K_L-K_S mass difference and the K_S width, by describing K_L as a bound state embedded in the continuum. The models results for states containing one b quark are also discussed.Received: 7 June 2003, Revised: 20 October 2003, Published online: 18 December 2003PACS: 12.40.Yx, 14.40.Aq, 14.40.Lb, 13.25.Es, 13.25.Ft, 13.75.Lb     

Assignment of Isodoublet of 2^3S1 Meson Nonet

Inserting the masses of some states, which have been established in theexperiments or the theory of lattice QCD, we investigate the mass of theisodoublet of the 2³S₁ meson nonet. The agreement results, 1567±22.6MeV and 1576.8MeV, are given by two different approaches. We suggest that the assignment of 2³S₁ meson nonet should be re-examined in future experiments.     

The forgotten 1D2 level of charmonium

The standard “charmonium” picture predicts four C=+1 states (³P₀, ³P₁, ³P₂, 2 ¹S₀) between ψ and ψ′. If these are identified with the four experimentally observed levels, serious difficulties arise. We remark that a ,,forgotten” ¹D₂ level (J^PC=2^?) is likely to be around 3.5 GeV. It may be identified with χ(2.45) or χ(3.50), avoiding the above above difficulties. The 2 ¹S₀ level has then yet to be discovered.     

Durees de vie des niveaux 1D2 ET 1S0 du magnesium

Radiative lifetimes of the excited n¹S₀ (n = 4, 5) and n¹D₂ (n = 3, 4) states in magnesium have been measured by time resolved fluorescence technique using two photon excitation.     

Relativistic calculations of 3s2 1S0-3s3p 1P1 and 3s2 1S0-3s3p 3P1,2 transition probabilities in the Mg isoelectronic sequence

Using the multi-configuration Dirac-Fock self-consistent field method and the relativistic configuration-interaction method,calculations of transition energies,oscillator strengths and rates are performed for the 3s 2 1 S 0-3s3p 1 P 1 spinallowed transition,3s 2 1 S 0-3s3p 3 P 1,2 intercombination and magnetic quadrupole transition in the Mg isoelectronic sequence(Mg I,Al II,Si III,P IV and S V).Electron correlations are treated adequately,including intravalence electron correlations.The influence of the Breit interaction on oscillator strengths and transition energies are investigated.Quantum electrodynamics corrections are added as corrections.The calculation results are found to be in good agreement with the experimental data and other theoretical calculations.     

Towards resolution of the scalar meson nonet enigma

By the application of a linear mass spectrum to a composite system of both the pseudoscalar and scalar meson nonets, we find three relations for the masses of the scalar states which suggest the assignment for the scalar meson nonet a₀(1320), K ₀ ^* (1430), f₀(1500), and f₀ ^′(980).     

Towards the understanding of 11P1 meson mass spectrum

Based on the meson-meson mixing and Regge trajectory, this paper establishes the mass relations which can describe the mass spectrum of 1^1 P1 meson state. Using these mass relations, it obtains the mass of K1B, hi （1380） and hc（1P） to be 1358.5MeV, 1468 MeV and 3543.9 MeV, respectively. The results are compared with other theoretical results and should be tested by experiments in the future.     

The relation between D and A1 axial-vector meson decays

We analyse the available information on the production and three-body decays of the D(1285) meson in an attempt to establish its relationship to the A₁(J^PC = 1⁺⁺) which mounting evidence suggests has a mass and width of 1100 and 250 MeV, respectively. In particular, we demonstrate that the narrow width of the D(20 to 30 MeV) is by no means incompatible with a broad A₁ and SU(3) symmetry. Taking due account of the possible existence of a K_A meson at 1340 MeV, we predict the decay properties of the ninth member of the nonet (the D') and argue that the E(1420) is not a viable candidate for this state.     

The multiplets of finite-width 0++ mesons and encounters with exotics

The complex-mass (finite-width) 0⁺⁺ nonet and decuplet are investigated by means of the exotic commutator method. The hypothesis of the vanishing of the exotic commutators leads to the system of master equations (ME). Solvability conditions of these equations define relations between the complex masses of the nonet and decuplet mesons which, in turn, determine relations between the real masses (mass formulae), as well as between the masses and widths of the mesons. Mass formulae are independent of the particle widths. The masses of the nonet and decuplet particles obey simple ordering rules. The nonet mixing angle and the mixing matrix of the isoscalar states of the decuplet are completely determined by solution of ME; they are real and do not depend on the widths. All known scalar mesons with the mass smaller than 2000 MeV (excluding σ(600)) and one with the mass belong to two multiplets: the nonet (a₀(980),K₀(1430),f₀(980),f₀(1710)) and the decuplet (a₀(1450),K₀(1950),f₀(1370),f₀(1500),f₀(2200)/f₀(2330)). It is shown that the famed anomalies of the f₀(980) and a₀(980) widths arise from an extra “kinematical” mechanism, suppressing decay, which is not conditioned by the flavor coupling constant. Therefore, they do not justify rejecting the qq̄ structure of them. A unitary singlet state (glueball) is included into the higher lying multiplet (decuplet) and is divided among the f₀(1370) and f₀(1500) mesons. The glueball contents of these particles are totally determined by the masses of decuplet particles. Mass ordering rules indicate that the meson σ(600) does not mix with the nonet particles.     

D* D1 and D D'*(2600) interactions and the charged charmonium-like state Z(4430)

The D^*D₁(2420) and DD'^*(2600) interactions are studied in a one-boson-exchange model. Isovector bound state solutions with spin parity J^P=1⁺ are found from the D^*D₁(2420) interaction, which may be related to the observed charged charmonium-like state Z(4430). There is no bound state solution found from the DD'^*(2600) interaction.     

Absolute measurement of an atomic cascade rate using a two photon coincidence technique. Application to the 4p21S0 -4s4p 1P1 -4s21S0 cascade of calcium excited by a two photon absorption

The two photon coincidence technique yields an absolute measurement of a cascade decay rate without knowing the detection efficiency of each detector. This method is applied to calcium atoms in an atomic beam excited to the 4p²¹S₀ state, and decaying via the resonant ¹P₁ state; it yields the excitation rate of the upper 4p²¹S₀ level. Since the excitation process (two photon absorption) is controlled, one can compute the excitation rate of the upper level as a function of the transition probabilities in the cascade. The lower transition is well known and we can therefore deduce the transition probability for the 4p²¹S₀ -4s4p ¹P₁, transition which previously had not been accurately determined. The preliminary measurements yield a line strength s = 0.98 ± 0.3 au in good agreement with a recent measurement of the lifetime of the 4p²¹S₀ state.     

Analytical potential energy function for the electronic states 2^∏1/2 and 2^∏3/2 of O^x2 （x=＋1, -1）

The splitting of potential energy levels for ground state X^2∏g of O^x2 （x = ＋1,-1） under spin-orbit coupling （SOC） has been calculated by using the spin-orbit （SO） multi-configuration quasi-degenerate perturbation theory （SO-MCQDPT）. Their Murrell-Sorbie （M S） potential functions are gained, and then the spectroscopic constants for electronic states 2^∏1/2 and 2^∏3/2 are derived from the M S function. The vertical excitation energies for O^x2 （x = ＋1,-1） are v[O2＋1^（2∏3/2→X^2∏1/2）] =195.652cm^-1, and v[O2^-1（2^∏1/2 →X^2∏3/2）] =182.568cm^-1, respectively. All the spectroscopic data for electronic states 2^∏1/2 and 2^∏3/2 are given for the first time.     

Facteur de lande du niveau 83S1 du mercure

The g_J factor of the 8³S₁ state of mercury has been measured with two different techniques. The obtained value is of the same order of magnitude as for the 7³S₁ state and larger than the Landé factor of the free electron.     

Impact broadening and shifts for 6sns 1S0 and 6snd 1D2 series of barium

Impact broadening and shifts of Ba transitions to parity forbidden Rydberg states have been measured using two-photon laser spectroscopy techniques. Broadening and shift rates for the 6sns ¹S₀ (10 < n < 19) and 6snd ¹D₂ (8 < n < 26) levels due to thermal collisional interactions with Xe, Kr and Ar as perturber gases are plotted. Perturbations due to configuration interactions are discussed.     

Doubly Charmed Exotic Mesons

We discuss the mass spectrum of doubly charmed mesons as hadronic molecules composed by D and D^* meson. Considering the heavy quark symmetry and chiral symmetry, we introduce the one-boson ( ${\pi , \rho , \omega}$ ) exchange potential between D and D^* meson. For all possible quantum numbers I(J ^P ) with isospin I, total angular momentum J( ≤ 2) and parity P, we solve the fully coupled channel Schrödinger equation. We find that in many quantum numbers the bound and resonant states composed by D or D^* meson can exist near the DD, DD^* and D^*D^* thresholds.