besⅲ实验上ψ→pφ分支比的测量和对λ-()振荡的寻找.docVIP

BESE实验上书(2S) f p⑺ ①分支比的测量和对A -(?)振荡的寻 找 At present, Standard Model (SM) is the most successful theory to explain the com-position and interaction of the matter, and QuantumChromo Dynamics (QCD) is the elementary theory of strong interaction in the framework of SM. The predictions of the QCDin the high energy regime have been extensively approved. However, QCDbe-comes invalid in the low energy regime due to the perturbative theory does not work in the case of the large effective coupling. Therefore, it is more important to study the hadron physics experimentally in the low energy regime, which is one of the main rea-sons that the Beijing Electron-Positron Collider (BEPC n ) operates at the center of-mass energy within 2.0 -4.6 GeV. According to the current knowledge, a mesonconsists of quark and anti-quark pair, and a baryon consists of three quarks. In addition, QCD also predicts the existence of the exotic states, such as the glueball, hybrid, multi-quark and molecule states and so on. The Beijing Spectrometer (BES E) is not only a gen-eral purpose magnetic spectrometer operating at BEPCII, but also a worldwide unique detector running at the energy region of 2.0 - 4.6 GeV. Since successfully constructed in 2008, BES E has accumulated the largest samples of J/ 书 and 书(2S) in the world.The decays of J/ 书 and 书(2S) can provide not only the unprecedented opportunity for studying the hadron spectroscopy, but also the excellent laboratory for searching the exotic states and new physics beyond the SM. In 2003, a strong enhancement near the pp mass threshold, known as the X(pp), was first observed by the BES n experiment in the radiative decay J/ 书—丫 pp. It was later confirmed by the CLEO and BES Eexperiments. In theory, X(pp) is assumed to be a baryonium, a multi-quark state or an effect due to pure final-state interaction (FSI), its nature has not been clarified yet. I n additi on, long time ago it was proposed that p ① product ion is well suited to search the exotic pen