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吴佳俊  S. Dulat  邹冰松 《中国物理 C》2010,34(9):1508-1511
A new particle Σ^ * with J ^P = 1/2^-was predicted by unquenched quark models with its mass around the well established Σ * (1385) with J P = 3/2 + .Here we re-examine some old data of the K^-p → Λπ^-π^ + reaction.Firstly we re-fit the data for kaon beam momenta in the range of 1.0 - 1.8 GeV.Secondly we study the reaction at the energies around Λ*(1520) peak.Both studies show evidence for the existence of Σ*with J^ P = 1/2^-around 1380 MeV.Higher statistic data on relevant reactions are needed to clarify the situation.  相似文献   

3.
We present measurements of the γγ* → π^0 transition form factor for the momentum transfer range Q^2=4-40 GeV^2 and the γγ* → ηc transition form factor for the range Q^2=2-50 GeV^2. The current status of measurements of the meson-photon transition form factors for the η and η' mesons is discussed. The results of the measurement of the ηc mass, total and two-photon widths are also presented.  相似文献   

4.
安春生 《中国物理 C》2009,33(12):1393-1396
Here we employ the extended chiral constituent quark model to investigate the five-quark components in the N* (1535) resonance. The axial charge of N*(1535) and the electromagnetic transition γ*N → N*(1535) are also analyzed. The results show that there may be sizable strangeness component in N*(1535).  相似文献   

5.
We revisit the form factors of B → K^* by using the heavy quark limit and large energy limit, assuming that the form factors have single pole forms near the zero recoil. The deviation from the single pole model is taken into account by adding a term proportional to (v. v′ - 1)2. On the other hand, we require the form factors to obey tile large recoil symmetry relationships when v . v′ becomes very large. A self-consistent set of B → K^* form factors is found. This set of form factors is checked to be consistent with the experimental data aboutB → K^*U modes.  相似文献   

6.
By employing the QCD factorization approach for the exclusive B→Vу decays, we study the exclusive decay B→K^*у in the top-quark two-Higgs-doublet mode/(T2HDM). Within the considered parameter space, we find the following conclusions (a) A hght charged-Higgs boson with a mass about 200 GeV is clearly excluded by the date of B→K^*у decay, and this lower limit is comparable with that from the inclusive B→X8*у decay; (b) The theoretical predictions for CP asymmetry of B→K^*у in the T2HDM is always less than 1% in size; and (c) The isospin symmetry breaking for B→K^*у decay in the SM and T2HDM considered here is around 6% in size and well consistent with the data and the general expectations.  相似文献   

7.
Klaus Gö  tzen 《中国物理 C》2010,34(6):638-643
The BES-Ⅲ Detector is a very versatile multipurpose device located at the Institute of High Energy Physics (IHEP) in Beijing, China. Concerning the physics program it ties stringently up to the past BES and BES-Ⅱ experiments. Since start of the data taking in the middle of 2008 the accumulated dataset of 200.10^6 J/ψ events and 100.10^6 ψ' events already exceeds the world data on these resonances. In addition to studies of the charmonium systems the data offers great opportunity for investigations in the light hadron sector. In detail it will be reported about the confirmation of the enhancement in pp invariant mass in radiative J/ψ decays, the search for decays Y(2175) → K*0K*0, observation of a charged K^± in K^±π^0 and observation of a new excited baryon N*(2065) decaying to pπ^0 and charged onjugate. The first result is based on data taken by BES-Ⅱ and BES-Ⅲ, the latter three on data collected by BES-Ⅱ only.  相似文献   

8.
The π^+π^ transition of heavy quarkonia in decay ψ(2S) →π^+π^-J/ψ is studied. With the BESII data on the decay ψ(2S) →π^+π^-J/ψ, we update the values of coupling constants (gi) and chromopolarizability (αψ(2s)J/ψ) in this process.  相似文献   

9.
As a sister work of[Phys. Rev. D 79 (2009) 094004], we incorporate the color-screening effect due to light quark pair creation into the heavy quark-antiquark potential, and investigate the effects of screened potential on the spectrum of bottomonimn. We calculate the masses, electromagnetic decays, and E1 transitions of bottomonium states. We find that the fine splittings between χbJ (J = 0, 1, 2) states are in good agreement with experimental data, and the E1 transition rates of γ(2S) → γχbJ(1P) and γ(3S) →γχbJ(2P) (J = 0, 1, 2) all agree with data within experimental errors. In particular, the mass of γ(6S) is lowered down to match that of the γ(11020), which is smaller than the predictions of the linear potential models by more than 100 MeV. Comparison between charmonium and bottomonium in some related problems is also discussed.  相似文献   

10.
This work studies the systematic reduced transition probabilities B(E2)↓, intrinsic quadrupole moments and deformation parameters of Pd isotopes with even neutrons from N =62 to 66. The downward reduced transition probabilities B(E2)↓from gamma transition 8^+to 6^+, 6^+ to 4^+, 4^+ to 2^+ and 2^+ to 0+states of even-even108 112Pd isotopes were calculated by the Interacting Boson Model(IBM-1) and compared with the available previous experimental results. The ratio of the excitation energies of the first 4+and the first 2+excited states, R4/2, is also studied for the classification of symmetry of these nuclei. Furthermore we have studied systematically the transition rate R = B(E2: L+ →(L 2)+)/B(E2 : 2+ →0+) of some of the low-lying quadrupole collective states in comparison with the available experimental data. The associated quadrupole moments and deformation parameters have been calculated. The results of this calculation are in good agreement with the corresponding available experimental data. The108 112Pd isotopes show the O(6) symmetry.  相似文献   

11.
A tull three-dimensional angular momentum projection on top ot a triaxial relativistic mean-fieid calculation is implemented for the first time. The underlying Lagrangian is a point coupling model and pairing correlations are taken into account by a monopole force. This method is applied for the low-lying excited states in ^24Mg. Good agreement with the experimental data is found for the ground state properties. A minimum in the potential energy surface for the 22^+ state, with β≈ 0.55,7 γ≈ 10^o, is used as the basis to investigate the rotational energy spectrum as well as the corresponding B(E2) transition probabilities as compared to the available data.  相似文献   

12.
李学潜 《中国物理 C》2010,34(2):267-269
The experimental observation indicates that the branching ratio of ψ'→ρπ is very small while the ρ-π channel is a main one in J/ψ decays. To understand the puzzle, various interpretations have been proposed. Meanwhile according to the hadronic helicity selection rule, this decay mode should be suppressed. Numerical calculations are needed to determine how it is suppressed. We calculate the branching ratios of J/ψ→ρπ and ππ in the framework of QCD. The results show that the branching ratios are proportional to (mu+md/MJ/ψ)^2 for the ρπ mode and (mu-md/MJ/ψ)^2 for the ππ mode which is isospin violated. The theoretical prediction of the ratio of J/ ψ→ρπ is smaller than data, but not too small to invoke a completely new mechanism. Thus the puzzle is still standing even though we learn much knowledge towards the puzzle and this will help to finally interpret the puzzle and then gain a deeper insight to the heavy quarkonia.  相似文献   

13.
A lattice gas model is presented for the A2 +2B2 → 2B2A reaction system with particle diffusion in two dimensions. In the model, B2 dissociates in the random dimer-filling mechanism and A2 dissociates in the end-on dimer filling mechanism. A reactive window appears and the system exhibits a continuous phase transition from a reactive state to a "B + vacancy" covered state with infinitely many absorbing states. When the diffusion of particle B is considered, there are only two absorbing states. It is found that the critical behavior of the continuous phase transition changes from the directed percolation (DP) class to the pair contact process with diffusion (PCPD) class.  相似文献   

14.
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/c^2 larger than the initial value and that of the FOCUS experiment is 1 MeV/c^2 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.  相似文献   

15.
Based on the assumption of two-quark structure of the scalar meson K0^*(1430), we calculate the CP-averaged branching ratios for B→K0^*(1430)η(') decays in the framework of the perturbative QCD (pQCD) approach here. We perform the evaluations in two scenarios for the scalar meson spectrum. We find that: (a) the pQCD predictions for Br(B→K0^*(1430)η(')) which are about 10^-5 10^-6, basically agree with the data within large theoretical uncertainty; (b) the agreement between the pQCD predictions and the data in Scenario Ⅰ is better than that in Scenario Ⅱ, which can be tested by the forthcoming LHC experiments; (c) the annihilation contributions play an important role for these considered decays.  相似文献   

16.
A new band in the odd proton nucleus ^123I is identified via in-beam γ-ray spectroscopy using the ^14N+^116Cd reaction. This band shows up as doublets with the previously assigned π97/2 (vh11/2)^2 band. Possible configurations of the new band are discussed in the framework of the cranked shell model and the geometrical model It is argued that the new band might be a chiral partner of the previously known πg9/2 (vh11/2)2 band.  相似文献   

17.
The electronic structure, lattice dynamics, and electron-phonon coupling of gallium-doped germanium are inves- tigated using ab initio supercell methods. Our results indicate the superconducting transition in gallium-doped germanium can be explained within a standard phonon mediated mechanism. The contribution of acoustic modes to the coupling constant A almost entirely comes from Ga related modes, and - 25% to λ. The calculated coupling constant is 0.35 and the corresponding transition temperature is 0.44 K for the gallium-doped germanium with 6.25% gallium content using Coulomb pseudopotential μ^* = 0.1, in agreement well with the experimental data.  相似文献   

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19.
徐庆君  Z. Was 《中国物理 C》2010,34(6):889-895
PHOTOS Monte Carlo is widely used for simulating QED effects in decay of intermediate particles and resonances. It can be easily connected to other main process generators. In this paper we consider decaying processes γ*→π^+π^-(γ) and K^±→π^+π^-e^±υ(γ) in the framework of Scalar QED. These two processes are interesting not only for the technical aspect of PHOTOS Monte Carlo, but also for precision measurement of αED(Mz), g--2, as well as ππ scattering lengths.  相似文献   

20.
刘晓海  张远江  赵强 《中国物理 C》2010,34(9):1402-1404
We propose one possible mechanism,i.e.,the vector meson (VV) rescattering effects,to interpret the near threshold narrow enhancement observed in J/ψ → γpp.The estimate indicates that these effects can give sizeable contributions to this channel,and a destructive interference between different rescattering amplitudes is required to reproduce the line shape of the data.  相似文献   

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