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1.
沈成平  苑长征 《中国物理 C》2010,34(8):1045-1051
A combined fit is performed to the BABAR and Belle measurements of the e^+e^- →φπ^+π^- and φf0(980) cross sections for center-of-mass energy between threshold and 3.0 GeV. The resonance parameters of the φ(1680) and Y(2175) are determined. The mass is (1681-12^+10) MeV/c^2 and the width is (221-24^+34) MeV/c^2 for the φ(1680), and the mass is (2117-49^+59) MeV/c^2 and the width is (164-80^+69) MeV/c^2 for the Y(2175). This information will shed light on the understanding of the nature of the excited φ and Y states observed in e+e- annihilation.  相似文献   

2.
In this article, we calculate the branching ratios of B→K0^* (1430)K decays by employing the pertur-bative QCD (pQCD) approach at leading order. We perform the evaluations in the two scenarios for the scalar meson spectrum. We find that (i) The leading order pQCD predictions for the branching ratio Br(B^+→K^+K0^*(1430)^0)are in good agreement with the experimental upper limit in both scenarios, while the pQCD predictions for other considered B→K0^*(1430)K decay modes are also presented and will be tested by the LHC experiments; (ii) The annihilation contributions play an important role in these considered decays, for B^0→K0^*(1430)^±K^± decays,for example,which are found to be (1-4)×10^-6.  相似文献   

3.
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   

4.
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.  相似文献   

5.
The decay channel ψ′→ π 〉+π^-J/ψ(J/ψ 〉 γp^-p) is studied using a sample of 1.06 × 10^8 ψ′ events collected by the BESIII experiment at BEPCII. A strong enhancement at threshold is observed in the p^-p invariant mass spectrum. The enhancement can be fitted with an S-wave Breit-Wigner resonance function with a resulting peak mass of M = 1861-13^+6 (stat)-26^+7 (syst) MeV/c^2 and a narrow width that is Г 〈 38 MeV/c^2 at the 90% confidence level. These results are consistent with published BESII results. These mass and width values do not match with well established mesons.  相似文献   

6.
Studies in which BABAR data have shown evidence for mixing in the neutral charm meson system are presented. A new measurement of the lifetime difference parameter ycp = (1.16±0.22±0.18)% is described. Results are also presented from a systematic study of DK and D*K invariant mass distributions from a 470 fb^-1 sample of asymmetric e^+e^- interactions recorded by the BABAR detector at the PEP-Ⅱ storage rings. A new charmed-strange meson has been observed with mass [3044 ± 8stat (-5^+30 )syst] MeV/c^2 and width [239± 35stat (-42^+46)syst]MeV/c^2.  相似文献   

7.
Properties of the ground state of ^178Hf and the isomeric state ^178Hf^m2 are studied within the adiabatic and diabatie constrained relativistic mean field (RMF) approaches. The RMF calculations reproduce well the binding energy and the deformation for the ground state of ^178Hf. Using the ground state single-particle eigenvalues obtained in the present eaiculation, the lowest excitation configuration with K^π = 16^+ is found to be v(7/2^-[514])^-1(9/2^+ [624])^1 π(7/2^+ [404])^-1 (9/2^-[514])^1. Its excitation energy caiculated by the RMF theory with time-odd fields taken into account is equal to 2.801 MeV, i.e., close to the ^178Hf^m2 experimentai excitation energy 2.446 MeV. The self-consistent procedure accounting for the time-odd component of the meson fields is the most important aspect of the present calculation.  相似文献   

8.
Abstract: The cross sections of e+e-→π+π-hc at center-of-mass energies from 3.90 to 4.42 GeV were measured by the BESIII and the CLEO-c experiments. Resonant structures are evident in the e+e-→π+π-hc line shape. The fit to the line shape results in a narrow structure at a mass of (4216±18) MeV/c2 and a width of (39±2) MeV, and a possible wide structure of mass (4293±9) MeV/c2 and width (222=k67) MeV. Here, the errors are combined statistical and systematic errors. This may indicate that the Y(4260) state observed in e+e-→π+π-J/ψ has a fine structure in it.  相似文献   

9.
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   

10.
We study whether the broad enhancement X(1576) arises from the final state interaction (FSI) of p(1450, 1700)→p^+ p^- →K^+ K^-decay,Both the absorptive and dispersive contributions of the above amplitudes are considered since the intermediate states are very close to p(1450, 1700). AThe same mechanism leads to a similar enhancement around 1580 MeV in the π^+ π^- specturm in the J/ψ →π^0 π^+ π^- channel, which can be used to test whether X(1576) can be ascribed to the FSI effect ofp(1450, 1700) → p^+ p^-.  相似文献   

11.
Stochastic Resonance in Neural Systems with Small-World Connections   总被引:1,自引:0,他引:1       下载免费PDF全文
We study the stochastic resonance (SR) in Hodgkin-Huxley (HH) neural systems with small-world (SW) connections under the noise synaptic current and periodic stimulus, focusing on the dependence of properties of SR on coupling strength c. It is found that there exists a critical coupling strength c^* such that if c 〈 c^*, then the SR can appear on the SW neural network. Especially, dependence of the critical coupling strength c^* on the number of neurons N shows the monotonic even almost linear increase of c^* as N increases and c^* on the SW network is smaller than that on the random network. For the effect of the SW network on the phenomenon of SR, we show that decreasing the connection-rewiring probability p of the network topology leads to an enhancement of SR. This indicates that the SR on the SW network is more prominent than that on the random network (p = 1.0). In addition, it is noted that the effect becomes remarkable as coupling strength increases. Moreover, it is found that the SR weakens but resonance range becomes wider with the increase of c on the SW neural network.  相似文献   

12.
This paper applies the symmetry-aziapted-cluster/symmetry-adapted-cluster configuration-interaction (SAC/SACCI) method to optimize the structures for X^1∑^+, A^1 Ⅱ and C^1 ∑^- states of SiO molecule with the basis sets D95++, 6-311++G and 6-311++G^**. Comparing the obtained results with the experiments, it gets the conclusion that the basis set 6-311++G^** is most suitable for the optimal structure calculations of X^1.∑^+, A^Ⅱ and C^1∑^- states of SiO molecule. The whole potential energy curves for these electronic states are further scanned by using SAC/6-311++G^** method for the ground state and SAC-CI/6-311++G^** method for the excited states, then use a least square method to fit Murrell~Sorbie functions, at last the spectroscopic constants and force constants are calculated, which are in good agreement with the experimental data.  相似文献   

13.
We determine the resonant parameters of the vector states φ(1680) and φ(2170) by performing a combined fit to the e+e-→ηφ cross sections from the threshold to 2.85 GeV measured by the BaBar,Belle,BESⅢ,and CMD-3 experiments.The mass(1678-3+5±7) MeV/c2 and width(156±5±9) MeV are obtained for φ(1680),and the mass(2169±5±6)MeV/c2 and width(96-14+17±9)MeV are obtained for φ(2170).The statistical significance ofφ(2...  相似文献   

14.
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   

15.
In the qq quark model, the states π2(1670) and η2(1645) are assigned as the I1D2 meson nonet. The partner of state η2(1645) needs further confirmation in the experiments. We employ the meson-meson mixing and the Regge trajectory methods to calculate the mass of the partner of state η2 (1645) to be 1879.8 MeV and 1863 ± 24 MeV respectively. We also calculate the strong decay width in the 3po decay model. These predictions can be compared with experiments in the future.  相似文献   

16.
E. Prencipe 《中国物理 C》2010,34(6):644-649
This paper intends to shortly summarize the recent results on Spectroscopy, published from the BABAR Collaboration. The BABAR experiment is a B-factory, at SLAC, where asymmetric energy beams of electron-positron are accelerated and collide at the energy in the center of mass of T(4S). In 9 years of data taking, BABAR had collected 433 fb^-1 equivalent luminosity on-peak-data at the T(4S) energy, 30 fb^-1 data at the T(3S) energy, 15 fb^-1 data at the T(2S) energy, and a scan around T(4S) was done, collecting 25 pb^-1 every 5 MeV. Thanks to the high luminosity achieved, it is possible to perform high precision measurements, and spectroscopy studies. An update on the measurement of the state X(3872) will be given, as final result published by using the whole dataset available. Then, a new preliminary Y(4260) measurement is reported, and the study of the invariant mass J/ψπ^+π^- in ISR events is shown, where no evidence of the state Y(4050) is highlighted. As conclusion, the results on the angular distribution analysis performed on the state Z(4430) are reported.  相似文献   

17.
任凭  邢志忠 《中国物理 C》2010,34(4):433-443
The lepton-number-violating decays of singly-charged Higgs bosons H^± are investigated in the minimal type-( Ⅰ+Ⅱ ) seesaw model with one SU(2)L Higgs triplet △ and one heavy Majorana neutrino N1 at the TeV scale. We find that the branching ratios B(H^+ → 1α^+υ^-) (for α = e,μ,τ) depend not only on the mass and mixing parameters of three light neutrinos υi (for i = 1, 2, 3) but also on those of N1. Assuming that the mass of N1 lies in the range of 200 GeV to 1 TeV, we figure out the generous interference bands for the contributions of υi and N1 to B(H^+→ 1α^+υ^-). We illustrate some salient features of such interference effects by considering three typical mass patterns of υi, and show that the relevant Majorana CP-violating phases can affect the magnitudes of B(H^+→ 1α^+υ^-)) in this parameter region.  相似文献   

18.
The comparison between single-point energy scanning (SPES) and geometry optimization (OPT) in determining the equilibrium geometries of c^3∑g^+ and B^1-Пu states of dimer 7Li2 is made at numerous basis sets by using a symmetryadapted-cluster configuration-interaztion (SAC-CI) method in the Gaussian 03 program package. In this paper the difference of the equilibrium geometries obtained by SPES and by OPT is reported. The results obtained by SPES are found to be more reasonable than those obtained by OPT in full active space at the present SAC-CI level of theory. And the conclusion is attained that the cc-PVTZ is a most suitable basis set for these states. The calculated dissociation energies and equilibrium geometries are 0.8818 eV and 0.3090 nm for c^3∑g^+ state, and 0.3668 eV and 0.2932 nm for B^1-Пu state respectively. The potential energy curves are calculated over a wide internuclear distance range from about 2.5α0 to 37α0 and have a least-squares fit into the Murrell-Sorbie function. According to the calculated analytic potential energy functions, the harmonic frequencies (We) and other spectroscopic data (ωeXe, Be and αe) are calculated. Comparison of the theoretical determinations at present work with the experiments and other theories clearly shows that the present work is the most complete effort and thus represents an improvement over previous theoretical results.  相似文献   

19.
We present a study of the inclusive photon spectra from 5.9 million J/ψ decays collected with the KEDR detector at the VEPP-4M e+e collider. We measure the branching fraction of radiative decay J/ψ→ηcγ, ηc width and mass. Our preliminary results are: M(ηc) = 2979.4± 1.5 ± 1.9 MeV/c^2, Г(ηc) = 27.8±5.1 ±3.3 MeV, B(Jψ→ηcγ) = (2.34±0.15±0.40)%.  相似文献   

20.
Charmed meson charmonium spectra are studied with improved quark actions on anisotropic lattices. We measured the pseudo-scalar and vector meson dispersion relations for four lowest lattice momentum modes with quark mass values ranging from the strange quark to charm quark with three different values of gauge coupling β and four different values of bare speed of light v. With the bare speed of light parameter v tuned in a mass-dependent way, we study the mass spectra of D, Ds, ηc, D^*, D^*s and J/ψ mesons. The results extrapolated to the continuum limit are compared with the experiment, and a qualitative agreement is found.  相似文献   

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