The non-local vacuum condensates of quantum chromodynamics (QCD) describe the distributions of quarks and gluons in the non-perturbative QCD vacuum state. Physically, this means that vacuum quarks and gluons have a nonzero mean-squared momentum in the vacuum, called virtuality. The quark virtuality is given by the ratio of the local quark-gluon mixed vacuum condensate to the quark local vacuum condensate. The gluon virtuality is expressed by gluon vacuum condensates and four-quark vacuum condensates. We study the two virtualities by solving Dyson-Schwinger Equations and calculating quark and gluon vacuum condensates. Our theoretical results for quark virtuality are in good agreement with many other theoretical model predictions such as QCD sum rules and lattice QCD calculations. Our calculation on gluon virtuality is initial and the results are quite interesting.
ZHOU LiJuan1, QIN SongMei2, WU Qing3 & MA WeiXing4 1 Collaboration Group of Hadron Physics and Non-perturbative QCD Study, Guangxi University of Tech- nology, Liuzhou 545006, China
The principle of the method for the BESIII TOF calibration using cosmic ray data without magnetic field are reported in this paper. After applying calibration constants, the single-end readout time resolution could reach about 150 ps, and the time resolution for one layer is achieved to be about 110 ps. The paper also described the extraction scheme for the event start time of cosmic events.
The short-range correlation between nucleons in finite nuclei is investigated in high energy protonnucleus and α-nucleus elastic scattering in the framework of Glauber multiple scattering theory without any free parameters. The effects on the p-^4He and ^4He-^12C elastic scattering, and in particular on the proton elastic scattering off hallo-like nuclei, ^6,8He, are estimated. Our calculations show that the short-range correlations play an important role in reproducing experimental data and could be also thought of as being possible origin and nature of halo-like phenomena in the nuclear structure. More accurate calculations along this line are needed.
