分类： 物理学 >> 凝聚态:结构、力学和热性能 提交时间： 2017-03-26
摘要： To achieve a high precision τ mass measurement at BESIII, two free para-meters (mτ and ε) and three parameters (mτε and σBG)fittings are simulated using sampling technique. For two parameters fitting, two points should be taken, the one is near the threshold of τ+τ- production to determine mτ , the other point is at 3.595 GeV to determine e±ciency. The ratio of luminosity at the two points is 3 to 1. For three parameters fitting, one point should be added at the low energy region with about 10% of the total luminosity. The optimal ratio of luminosity at the other two points is still 3 to 1.
分类： 物理学 >> 凝聚态:结构、力学和热性能 提交时间： 2017-03-26
摘要： e+e− experiments at charmonium production threshold are reviewed, it is found that the contribution of the continuum process via virtual photon has been neglected in almost all the experiments and most channels analyzed. It is pointed out that the contribution of the continuum part may affect the final results significantly in ψ(2S) and ψ(3770) decays, while the interference between the continuum amplitude and the resonance amplitude may even affect the J/ψ decays as well as the ψ(2S) and ψ(3770). This leads to the revise of the analysis of strong and electromagnetic amplitude in ψ(2S) decays, including ψ(2S) → V P which is the long lasting puzzle between J/ψ and ψ(2S) decays. For ψ(3770) physics, a large constructive interference for light hadron modes and destructive interference for DD could be responsible for the discrepancy between the larger cross section of inclusive hadrons by direct measurement of e+e− → ψ(3770) → hadrons than the DD cross section measured using D single-tag and double-tag method.
分类： 物理学 >> 核物理学 提交时间： 2016-09-13
摘要： In many high energy experiments, the physics quantities are obtained by measuring the cross sections at a few energy points over an energy region. This was referred to as scan experiment. The optimal design of the scan experiment (how many energy points, what the energies are, and what is the luminosity at each energy point) is of great significance both for scientific research and from economical viewpoint. Two approaches, one has recourse to the sampling technique and the other resorts to the analytical proof, are adopted to figure out the optimized scan scheme for the relevant parameters. The final results indicate that for爊爌arameters scan experiment,爊爀nergy points are necessary and sufficient for optimal determination of these爊爌arameters; each optimal position can be acquired by single parameter scan (sampling method), or by analysis of auxiliary function (analytic method); the luminosity allocation among the points can be determined analytically with respect to the relative importance between parameters. By virtue of the second optimization theory established in this paper, it is feasible to accommodate the perfectly optimal scheme for any scan experiment.
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