共查询到20条相似文献,搜索用时 31 毫秒
1.
M. Ablikim et al 《中国物理C(英文版)》2012,36(11):1031-1039
Based on 58 million J/ψ events collected by the BESⅡ detector at the BEPC, J/ψ→ΛΛ π+π- is observed for the first time. The branching fraction is measured to be Br(J/ψ→ΛΛ π+π-)=(4.30±0.13±0.99)×10-3, excluding the decays to intermediate states, namely J/ψ→Ξ-Ξ+, J/ψ→Σ(1385)-Σ(1385)+, and J/ψ→Σ(1385)+Σ(1385)-. The branching fractions for these intermediate resonance channels are measured to be:Br(J/ψ→Ξ-Ξ+)=(0.90±0.03±0.18)×10-3, Br(J/ψ→Σ(1385)-Σ(1385)+)=(1.23±0.07±0.30)×10-3,and Br(J/ψ→Σ(1385)+Σ(1385)-)=(1.50±0.08±0.38)×10-3, respectively. The angular distribution is of the form dN/d(cosθ)α(1+αcos2θ) with α=(0.35±0.29±0.06) for J/ψ→Ξ-Ξ+, α=(-0.54±0.22±0.10) for J/ψ→Σ(1385)-Σ(1385)+, and α=(-0.35±0.29±0.06) for J/ψ→Σ(1385)+Σ(1385)-. 相似文献
2.
The mass spectrum of the J/ψ meson family can't be explained by the MIT bagmodel.Based on the theory of our Rubber Bag model of hadrons,the mass spectrumof the ordinary hadrons and that of the J/ψ family (ψ(3772) included) are calcula-ted in a unified way in this paper.The results so obtained conform well to experi-mental data. 相似文献
3.
BES Collaboration 《中国物理C(英文版)》1995,19(8):673-685
The cross sections of e+e-→hadrons,e+e-,μ+μ-have been measured in the vicinity of J/ψresonance at BES/BEPC.The fit of the observed cross sections gives the new results of J/ψ resonance parameters:the partial widths to hadrons,electrons and muous are Γh=74.1±8.1keV,Γe= 5.14±0.39keV and Γμ=5.13±0.52keV respectively;the total width Γ=84.4±8.9keV;the branching fractions Γh/Γ=(87.8±0.5)%,Γe/Γ=(6.09± 0.33)%,and Γμ/Γ=(6.08±0.33) %. 相似文献
4.
Treating Lee Model by Slac method,we find that,to state ||V> of one particle and state ||VN> of two particles,there corresponds a solution of Slac bag type re-spectively.The latter bears resemblance to the former in energy especially for ||V> state with the replacement of the interaction constants g by g/√e only.In addition,the“bag”corresponds precisely to the scalar field in ||V> and ||VN> states.However,for ψN- and ψV- field,we get δ-function type solutions by Slac method.They deviate greatly from the rigorous solutions.The“skin confinement”as statedby Bardeen et al.,and Rafelski is closely related to the δ-confinment in the one par-tiele state found here by coherent state approximation.Thus it may not representthe physical picture in the rigorous solution of a quantum field theory. 相似文献
5.
HADRONIC PRODUCTION OF J/ψ、ψ′(3684) AND THE CONTENT OF THE CHARMED STRATONS IN THE SEA OF THE STRATONS 下载免费PDF全文
Hadronic production of J/ψ、ψ′(3684) particles is discussed in this paper on thebasis of reference [1] after considering the massive effects of the charmed straton.The results of [1] are improved.With the aid of the decay of ψ″→DD and the effective coupling constant between ψ″(3772) and the charmed straton we estimate that the content of the charmed stratonin the sea of the stratons is 0.41% of the ordinary stratons at most. 相似文献
6.
M. Ablikim et al 《中国物理C(英文版)》2012,36(11):1040-1045
The decay ψ(2S)→Ω-Ω+ is analyzed using 14×106 ψ(2S) events recorded by the Beijing Spectrometer Ⅱ (BESⅡ) at the Beijing Electron Positron Collider (BEPC). Based upon events with no missing charged tracks and a satisfactory four-constraint kinematic t, we determine the upper limit for the branching fraction of ψ(2S)→Ω-Ω+ to be 1.5×104 at a 90% confidence level. By including events with one missing charged track, we are able to report the first evidence of an Ω+ signal with a statistical signi cance of 3.1|σ. The branching fraction of ψ(2S)Ω+ is determined to be (4.80±1.56(stat)±1.30(sys))105. 相似文献
7.
APPROXIMATE B.S. WAVE FUNCTIONS FOR AN ELECTROMAGNETIC BOUND SYSTEM OF SPINS (1/2, 1/2) OR (1/2, 1/2) WITH UNEQUAL MASSES 下载免费PDF全文
The Bethe-Salpeter equation for an electromagnetic bound system of spins (1/2—1/2) or (1/2—1/2) with unequal masses are solved in this paper. The approximate B.S. wave functions for these systems are given. Utilising these wave functions, the decay rate and branching ratio for Ξ0→(Σ+μ-)+vμ are calculated with accuracy up to order O(α). The results are wΞ0→(Σ+μ-)+vμ1.12(1/sec) and R=[wΞ0→(Σ+μ-)+vμ]/[wΞ0→(Σ+μ-)+vμ]4.7×10-7. Similarly, the process Λ→(pμ-)+vμ is also discussed. 相似文献
8.
BES Collaboration 《中国物理C(英文版)》1996,20(6):481-490
From a study of(2S)decays into vector-pseudoscalar final states,ρπ and KK*,based on a sample of 1.27×106 produced (2S) events,we have set upper limits at 90% confidence level on the branching fractions into ρπof 3.6×10-5, into K+K*+c.c.of 2.5×10-5,and into K0K*0+c.c.of 1.2×10-4.We find that all these decays are substantially suppressed relative to the corresponding J/ψ decays in comparison with PQCD predictions.Our results confirm the MARK Ⅱ measurements at an improved sensitivity level. 相似文献
9.
BES Collaboration 《中国物理C(英文版)》2002,26(1):8-16
The decay mode of J/ψ→π03(π+π-) was studied very little before. There are no informations except branching ratios for this channel in PDG book which based on less than 0.2×106J/ψ events of MARKⅠ. Now, BESⅠ has a data sample of 7.8×106J/ψ events, we can make more accurate results than MARKⅠ. Total of 3290±43 J/ψ→π03(π+π-) events including 1275±86 J/ψ→ω2(π+π-) events are selected. J/ψ→π03(π+π-) and J/ψ→ω2(π+π-) events have been generated with MC simulition for calculating events selection efficiency. BESⅠ result is: Br(J/ψ→π03(π+π-))=(2.52±0.06±0.43)% and Br(J/ψ→π03(π+π-))=(1.31±0.09±0.21)%. Meanwhile, we studied the invariant mass of 4π and ωππ to find interesting signals. It seems that there is a peak at about 1.74GeV in the invarianat mass spectrum of 4π, and a enhancement was also found at about 1.9GeV in the invariant mass spectrum of ωππ. It is not clear whether they are from resonances or background. Therefore, more work in detail is still going on. 相似文献
10.
BES Collaboration 《中国物理C(英文版)》1996,20(2):97-106
Two processes ψ(2S)→π+π-J/ψ,J/ψ→1+1- and J/ψ→anything are carefully studied to get the J/ψ leptonic branching fractions with the ψ(2S)data at BES/BEPC.The results are B(J/ψ→e+e-)=(5.90±0.07±0.16)% and B(J/ψ→μ+μ-)=(5.96 ±0.08±0.16)%,and Be/Bμ is estimated to be 0.990±0.018±0.024.Assuming Be=Bμ,the leptonic branching fraction of the J/ψ is B(J/ψ→1+1-)=(5.93±0.05 ± 0. 16 )%.This result is used to estimate the QCD scale factor ∧(nf/MS) and the strong coupling constant αs. 相似文献
11.
Mark B. Wise 《Physics letters. [Part B]》1980,89(2):229-231
The branching ratio for the decay B → J/ψ + hadrons is estimated from a calculation of the quark decay b → J/ψ + s. 相似文献
12.
BES Collaboration 《中国物理C(英文版)》1998,22(2):97-105
The channels of J/ψ decay into,ΛΛ,ΛΛγ and ΛΛπ0 are analyzed with 7.8×106 J/ψ events collected by BES detector at BEPC Collider.The branching ratios for three channels and the angular distribution for the first channel are measured.The branching ratios are Br(J/ψ→ΛΛ)=(l.08±0.06±0.24)×10-3,Br(J/ψ→ΛΛγ)-4(90% CL)and Br(J/ψ→ΛΛπ0)=(2.3±0.7±0.8)×l0-4 respectively. The angular distribution for J/ψ→ΛΛ is dN dcosθ=N0(1+αcos20),α=0.52±0.33±0.13. 相似文献
13.
BES Collaboration< BR> BAI Jing-Zhi BAN Yong BIAN Jian-Guo CAI Xiao CHANG Jin-Fan CHEN Hai-Xuan CHEN He-Sheng CHEN Hong-Fang CHEN Jiang-Chuan CHEN Jin CHEN Jun CHEN Ma-Li CHEN Yuan-Bo CHI Shao-Peng CHU Yuan-Ping CUI Xiang-Zong DAI Hong-Liang DAI You-Shan DENG Zi-Yan DONG Liao-Yuan DU Shu-Xian DU Zhi-Z 《中国物理C(英文版)》2004,28(4):325-331
Evidence of ψ(3770) decays to a non-DD final state is observed. A total of 6.8±3.0 ψ(3770)→J/ψ→π+π— events are obtained from a data sample of 8.0±0.5 pb-1 taken at center-of-mass energies around 3.773GeV using the BES-Ⅱ detector at the BEPC. The branching fraction is determined to be BF(ψ(3770)→J/ψ→π+π—)=(0.59±0.26±0.16)%, corresponding to the partial width of Γ(ψ(3770)→J/ψπ+π—)=(139±61±41)keV. 相似文献
14.
BES Collaboration 《中国物理C(英文版)》1995,19(4):289-295
Based on 7.8×106 J/ψ events collected by the BES at BEPC, through study of the hadronic decays J/ψ→φπ+π- and J/ψ→ωπ+π-, the branching ratios of the processes and the mass positions and the widths of f0 are obtained. The angular distributions of J/ψ→φf0,f0→π+π-, are fitted and the helicity amplitude ratio of this process is first given. 相似文献
15.
YANG Bo-Jun 《中国物理C(英文版)》1986,10(1):98-103
The rotation-vibration spectra of nuclear molecule 12C+12C is chassified by the irreducible representations of group U(5). It is shown that the symmetry of rotation-vibration levels of nuclear molecule 12C+12C are discribed by means of dynamical symmetry U(5)U(4)O(4)O(3). 相似文献
16.
BES Callaboration 《中国物理C(英文版)》2002,26(2):93-99
With 7.8 million produced J/ψ events collected by the BES detector at the BEPC, the decay J/ψ→Σ0Σ0 is analysed. The branching ratio is measured to be BR(J/ψ→Σ0Σ0)=(0.97±0.04±0.24)×10-3. The angular distribution is of the form dN dcosθ=N0(1+α cos2θ) with α value of -0.21±0.27±0.13. 相似文献
17.
18.
BES Collaboration 《中国物理C(英文版)》1993,17(2):97-106
Based on the 2.5 million J/ψ's collected by the BES at BEPC,through the hadronic decay J/ψ→ωf2(1270),f2(1270)→π+π-,ω→π+π-π0,the properties of the resonance f2(1270) are studied:its mass,width,and branching ratio.the angular distribution is fitted with maximum likelihood methood,determining its.JPC=2++ and giving in the first time the helicity amplitude ratios of this process as:x=0.99±0.29; y=-0.24±0.17; z1=0.90±0.57;z2=0.56±0.22. 相似文献
19.
TESTING GLUON DISTRIBUTION FUNCTION OF HADRONS IN LARGE PT PROCESS WITH DIRECT PHOTON EMISSION 下载免费PDF全文
In this paper we disscuse disscuse the physicsical aspect of cross-section differences ΔABcγ=dσ(AB→cγX)-dσ(AB→cγX) and give the simple rules to select the elementary subprocesses which contribute to cross-section differences.
We bind a way to test the gluon distribution functions of hadrons through the measurement of cross-section difference or combination of cross-section differences in the large PT process with direct photon emission. Moreover we obtain simple relations between each combination of cross-sections and the corresponding gluon distribution functions of proton, neutron, pion and daon:
Gp8(x)/(Δpphγ-Δpphγ)=Gn8(x)/(Δpphγ)=Gπ8(x)/(Δπ+phγ+Δπ-phγ=GK8(x)/(ΔK+phγ+ΔK-phγ)which are expected to be test in experiment. 相似文献
We bind a way to test the gluon distribution functions of hadrons through the measurement of cross-section difference or combination of cross-section differences in the large PT process with direct photon emission. Moreover we obtain simple relations between each combination of cross-sections and the corresponding gluon distribution functions of proton, neutron, pion and daon:
Gp8(x)/(Δpphγ-Δpphγ)=Gn8(x)/(Δpphγ)=Gπ8(x)/(Δπ+phγ+Δπ-phγ=GK8(x)/(ΔK+phγ+ΔK-phγ)which are expected to be test in experiment. 相似文献
20.
LIU Jin-Sheng HUANG Jing CHEN Ding ZHANG Ying ZHAI Liu-Ming CHEN Xu HU Xiao-Bin LIN Yu-Hui ZHANG Xue-Yao FENG Cun-Feng JIA Huan-Yu ZHOU Xun-Xiu CHEN Tian-Lu LI Hai-Jin LIU Mao-Yuan YUAN Ai-Fang 《中国物理C(英文版)》2015,39(8):086004-086004
Aiming at the observation of cosmic-ray chemical composition in the "knee" energy region, we have been developing a new type of air-shower core detector(YAC, Yangbajing Air shower Core detector array) to be set up at Yangbajing(90.522?E, 30.102?N, 4300 m above sea level, atmospheric depth: 606 g/m2) in Tibet, China.YAC works together with the Tibet air-shower array(Tibet-Ⅲ) and an underground water Cherenkov muon detector array(MD) as a hybrid experiment.Each YAC detector unit consists of lead plates of 3.5 cm thickness and a scintillation counter which detects the burst size induced by high energy particles in the air-shower cores.The burst size can be measured from 1 MIP(Minimum Ionization Particle) to 106 MIPs.The first phase of this experiment, named"YAC-Ⅱ ", consists of 16 YAC detectors each with a size of 40 cm×50 cm and distributed in a grid with an effective area of 10 m2.YAC-Ⅱ is used to check hadronic interaction models.The second phase of the experiment, called"YAC-Ⅱ ", consists of 124 YAC detectors with coverage of about 500 m2.The inner 100 detectors of 80 cm×50 cm each are deployed in a 10×10 matrix with a 1.9 m separation; the outer 24 detectors of 100 cm×50 cm each are distributed around these to reject non-core events whose shower cores are far from the YAC-Ⅱ array.YAC-Ⅱ is used to study the primary cosmic-ray composition, in particular, to obtain the energy spectra of protons, helium and iron nuclei between 5×1013eV and 1016 eV, covering the "knee" and also connected with direct observations at energies around 100 TeV.We present the design and performance of YAC-Ⅱ in this paper. 相似文献