共查询到20条相似文献,搜索用时 15 毫秒
1.
We search for the ψ(4S) state in the B~±→ηJ/ψK~± and e~+e~-→ηJ/ψ processes based on the Belle measurements with the assumed mass M =(4230±8) MeV/c~2 and width Γ =(38±12) MeV. No significant signal is observed in the ηJ/ψ mass spectra. The 90% confidence level upper limit on the product branching fraction B(B~±→ψ(4S)K~±)B(ψ(4S)→ηJ/ψ) 6.8×10~(-6) is obtained in the B~±→ηJ/ψK~± decays. By assuming the partial width of ψ(4S)→e~+e~-to be 0.63 ke V, a branching fraction limitB(ψ(4S)→ηJ/ψ) 1.3% is obtained at the 90%confidence level in e~+e~-→ηJ/ψ, which is consistent with the theoretical prediction. 相似文献
2.
M. Ablikim M. N. Achasov X. C. Ai O. Albayrak M. Albecht D. J. Ambrose A. Amoroso 《中国物理C(英文版)》2016,40(11):113001-113001
By analyzing 2.93 fb-1 data collected at the center-of-mass energy √s=3.773 GeV with the BESIII detector, we measure the absolute branching fraction of the semileptonic decay D+→K0e+ve to be B(D+→K0e+ve)=(8.59±0.14±0.21)% using K0→KS0→π0π0, where the first uncertainty is statistical and the second systematic. Our result is consistent with previous measurements within uncertainties.. 相似文献
3.
Experimental study of cross-section ratios in the collisions of Cq+ and oq+(q= 1-4) on atomic helium in strong-interaction region 下载免费PDF全文
We have measured the cross-section ratios of helium induced by Cq+ and Oq+ (q=1-4) in an energy range from 20 keV/amu to 500 keV/amu, and obtained the two-dimensional spectra by employing the coincidence method combined with the MPA-3 data acquisition system. Hence, we obtain the ratios of total single-ionization cross-sections (SI, SC, SLSI, and DLSI), total double-ionization cross-sections (DI, DC, TI, SLDI, and DLDI) and cross-sections of every process (SI, SC, SLSI, DLSI, DI, DC, TI, SLDI, and DLDI), which induce the single-ionization and double-ionization, to the total cross sections respectively. The competitive relations between the reaction-channels and the experimental data law of each reaction-channel are revealed explicitly, and the qualitative explanations involved in those results are also presented accordingly. 相似文献
4.
《The European Physical Journal C - Particles and Fields》2007,52(3):531-542
The inclusive production cross sections of the charmed mesons D0,D+,Ds
+ and D*+ have been measured in interactions of 920 GeV protons on C, Ti, and W targets with the HERA-B detector at the HERA storage
ring. Differential cross sections as a function of transverse momentum and Feynman’s x variable are given for the central
rapidity region and for transverse momenta up to pT=3.5 GeV/c. The atomic mass number dependence and the leading to non-leading particle production asymmetries are presented as well.
PACS 13.85.Ni; 24.85.+p; 13.20.Fc 相似文献
5.
Wen-Long Yuan Xiao-Cong Ai Xiao-Bin Ji Shen-Jian Chen Yao Zhang Ling-Hui Wu Liang-Liang Wang Ye Yuan 《中国物理C(英文版)》2016,40(2):026201-026201
Based on J/ψ events collected with the BESIII detector,with corresponding Monte Carlo samples,the tracking efficiency and its systematic uncertainty are studied using a control sample of J/ψ→ppπ~+π~-.Validation methods and different factors influencing the tracking efficiency are presented in detail.The tracking efficiency and its systematic uncertainty for protons and pions with the transverse momentum and polar angle dependence are also discussed. 相似文献
6.
V. Chabaud B. Hyams T. Papadopoulou K. Rybicki P. Weilhammer H. Becker G. Blanar M. Cerrada H. Dietl J. Gallivan B. Gottschalk E. Lorenz G. Lütjens G. Lutz W. Männer B. Niczyporuk D. Notz J. De Groot 《Nuclear Physics B》1980,175(2):189-196
We have studied A2? production by π? on a nuclear target in the K?KS0 decay channel, where the A2? is observed above a small background at 17.2 GeV/c incident momentum. Direct confirmation of coherent A2 (JP = 2+) production has been found. 相似文献
7.
Douglas E. Thornton 《Optics Communications》2011,284(12):2890-2894
The saturation absorption technique is applied to the 87Rb 2S1/2 F″ = 2 → 2P3/2 F′ = 1, 2 and 3 transitions to study the effect of velocity changing collisions (VCC). The VCC caused Doppler pedestal increases with argon pressure from 0 to 110 mTorr and decreases with modulation frequencies of 700-3200 Hz. The resonances of the velocity selective, saturated optical pumping are washed out for pressure of 110 mTorr. The magnitude of the Doppler pedestal relative to the homogeneous features, yields a rate for velocity changing collisions of 6.5 ± 0.2 × 10−10 cm3 s−1. 相似文献
8.
《The European Physical Journal A - Hadrons and Nuclei》2008,35(3):291-293
In photoproduction experiments, a large number of final states yielding various resonance contributions are accessible. To
extract resonance parameters via partial-wave analysis not only the measurement of differential cross-sections is necessary,
but also the determination of polarization observables. At the electron accelerator ELSA (Bonn) the coherent bremsstrahlung
method was used to generate a linearly polarized photon beam. Using the CBELSA/TAPS detector setup, the beam asymmetry Σ in
the reaction γp → pπ0η was determined as a function of various masses and angles for photon energies between 970MeV and 1650MeV. 相似文献
9.
强磁场下的重粒子碰撞激发过程是重要的非弹性碰撞过程, 但相关研究还几乎是空白. 应用经典蒙特卡洛的方法在得到无磁场下He2++H(1s)的碰撞激发截面的基础上, 详细研究了不同强度的纵向和横向强磁场环境下到不同主量子数n和磁量子数m的碰撞激发过程的态选择截面. 同时用非微扰量子方法, 得到了强磁场下靶原子的能级, 并分析了其随磁场强度变化的原因. 对碰撞过程发现由于磁场的引入导致到不同m态的激发截面有较大的分离, 同时在较低入射能区的态选择截面变化行为与磁场方向有很大关系, 这与能级变化及横向强磁场所特有的抗磁项的相互竞争有密切联系. 通过对有关事例、径迹的分析, 解释了这些变化形成的原因. 也发现由于核的运动, 沿磁场方向的轨道角动量并非绝对守恒, 而有微小的变化.
关键词:
重粒子碰撞激发
经典蒙特卡洛模拟
强磁场
态选择截面 相似文献
10.
This paper reports that the ratios of double to single electron loss cross-section (R) of O^2+ in collision with Ar and He at the velocity of 1 -4 vo(vo is the Bohr velocity) have been obtained by the coincidence technique. The trend of R - V in the experiment indicates that the effective charge varies with injected velocity. The effective charge can be obtained by the n-body classical trajectory Monte Carlo method, which is interpreted by the molecular Coulomb over barrier model. 相似文献
11.
The energy loss effects of the incident quark, gluon, and the color octet ccˉ on J/ψ suppression in p-A collisions are studied by means of the experimental data at E866, RHIC, and LHC energy. We extracted the transport coefficient for gluon energy loss from the E866 experimental data in the middle x F region(0.20 x F 0.65) based on the Salgado-Wiedemann(SW) quenching weights and the recent EPPS16 nuclear parton distribution functions together with nCTEQ15. It was determined that the difference between the values of the transport coefficient for light quark, gluon, and heavy quark in cold nuclear matter is very small. The theoretical results modified by the parton energy loss effects are consistent with the experimental data for E866 and RHIC energy, and the gluon energy loss plays a remarkable role on J/ψ suppression in a broad variable range. Because the corrections of the nuclear parton distribution functions in the J/ψ channel are significant at LHC energy level, the nuclear modification due to the parton energy loss is minimal. It is worth noting that we use the color evaporation model(CEM) at leading order to compute the p-p baseline, and the conclusion in this paper is CEM model dependent. 相似文献
12.
C. Kourkoumelis L.K. Resvanis T.A. Filippas E. Fokitis A.M. Cnops S. Iwata R.B. Palmer D.C. Rahm P. Rehak I. Stumer C.W. Fabjan T. Fields D. Lissauer I. Mannelli P. Mouzourakis A. Nappi W.J. Willis M. Goldberg G.C. Moneti 《Physics letters. [Part B]》1979,85(1):147-150
The correlation between a high transverse momentum π0and η and a second π0 have been measured using an apparatus with large azimuthal acceptance. The angular distribution of α, measuring the deviation from collinearity in azimuth, peaks near zero. The r.m.s. of the distribution is found to have an inverse logarithmic rather than a fall-off. 相似文献
13.
With a photon spectrum of high energy charged partons, both differential and total cross sections of J/ψ and Υ(1s) inclusive photoproduction in ultra-peripheral p-Pb Collisions (UPCs) at √s=5.5 TeV are given. A direct photon process and a resolved photon process including fragment and non-fragment contributions are considered. The total cross section is compared to the inelastic production results in coherent p-Pb collisions at the same center-of-mass energy. Our results seem non-negligible. 相似文献
14.
T.K. Balasubramanian G.L. Bhale M.N. Dixit N.A. Narasimham 《Journal of Molecular Spectroscopy》1981,88(2):259-263
Fluorescence was excited in the B3Πu(0+)-X1Σg+ system of diatomic iodine by means of the 5145-Å line of an Ar+ laser and the 6328-Å line of a HeNe laser. The resulting spectrum was recorded on a SPEX double monochromator and a quantitative measurement of the intensities was carried out. The variation of the electronic transition moment with R centroid observed by us shows a behavior similar to what has been reported earlier. 相似文献
15.
V. S. Pavlovich 《Journal of Applied Spectroscopy》2007,74(4):501-507
We used known experimental data to analyze the influence of intermolecular interactions on the position of the 0-0-band a1Δg → X3Σ
g
−
phosphorescence of molecular oxygen in solutions. A bathochromic (red) shift caused by dispersion interactions and fluctuations
of the internal electric field (induction effect) is analyzed employing new formulas obtained by us in the framework of the
Onsager model. The contributions from intermolecular repulsion and higher multipole interactions to the shift of the spectrum
are also discussed. It is found that the polarizability in the a1Δg state is higher than in the X3Σ
g
t-
state by 0.19 ± 0.03 Å3. Taking into account the induced nature of O2 phosphorescence in solutions, it is noted that the change of polarizability Δαeg = 0.19 Å3 should differ from the change of Δαeg inherent in free molecular oxygen.
__________
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 74, No. 4, pp. 453–459, July–August, 2007. 相似文献
16.
A.L.S. Angelis H.-J. Besch B.J. Blumenfeld L. Camilleri T.J. Chapin R.L. Cool C. del Papa L. Di Lella Z. Dimčovski R.J. Hollebeek L.M. Lederman D.A. Levinthal J.T. Linnemann C. Newman N. Phinney B.G. Pope S.H. Pordes K.K. Young 《Physics letters. [Part B]》1979,87(4):398-402
An apparatus consisting of a superconducting solenoid magnet, cylindrical drift-chambers, and two arrays of lead-glass ?erenkov counters has been used at the CERN ISR to study the production of e+e? pairs of invariant mass above 6.5 GeV/c2. Cross sections for the continuum and the ? family of resonances are presented, as well as the mean transverse momentum 〈pT〉 of the electron-positron pairs in the continuum and resonance region. 相似文献
17.
基于激光诱导击穿光谱技术, 利用Nd:YAG脉冲激光激发Al2O3 (含量为99%)陶瓷片产生等离子体, 获得了AlO自由基B2∑+–X2∑+跃迁的33条发射谱线. 就AlO自由基光谱的时间演化规律和激光能量对谱线的影响规律进行了研究与分析. 结果表明, AlO自由基光谱出现在Al原子和Al离子光谱之后, 且持续时间较长. 当激光的脉冲能量由10 mJ起不断增加时, AlO自由基光谱强度逐渐减小, 且最大值出现时间随激光能量的增加而后移. 在此基础上, 进行了陶瓷等离子体在空气和氩气环境下的对比试验, 发现从Al2O3陶瓷片中激发所产生的AlO自由基必须有空气中O2参与反应.
关键词:
激光诱导击穿光谱
AlO自由基
B2∑+–X2∑+跃迁光谱')" href="#">B2∑+–X2∑+跃迁光谱 相似文献
18.
19.
We propose a forward method based on PYTHIA6.4 to study the jet properties in ultra-relativistic pp collisions.In the forward method,the partonic initial states are first generated with PYTHIA6.4 and then hadronized in the Lund string fragmentation model,and finally the hadronic jets are constructed from the created hadrons.Jet properties calculated with the forward method for pp collisions at √s=7 TeV are comparable to those calculated with the usual anti-kt algorithm(backward method)in PYTHIA6.4.The comparison between the backward and forward methods may contribute to the understanding of the partonic origin of jets in the backward method. 相似文献
20.
U. Idschok P. Kobe F. Selonke B. Wessels V. Blobel H. Fesefeldt B. Hellwig D. Mönkemeyer P. Söding H. Franz J.W. Lamsa N. Schmitz W. Schrankel 《Nuclear Physics B》1973,53(2):282-288
A low-mass S-wave (ππ)0 enhancement is observed in the reaction pp → p (ππ)0 p at 12 and 24 GeV/c incident momentum. The mechanism for producing these low-mass pion pairs is investigated, and it is shown that double pomeron exchange can contribute at most 5% to their production cross section at 24 GeV/c. 相似文献