Exotic particles and perhaps new physics?

摘要

The last few years have witnessed phenomenal advances in experimental particle physics. A milestone achieved in accelerator physics was collisions of beams with more than 10~(17) articles/beam/cm~2/s. Efficient detectors, better beams and better data analysis have all led to many exciting discoveries. After thirty years of searching, five international collaborations have recently announced strong experimental evidence for a five-quark exotic particle named the theta-plus ((theta)~+). In April 2003 evidence for a new, narrow resonance (D_s~+ (2317)) with unexpectedly low mass was reported. A 'mystery meson', X(3872) as well as a new, narrow enhancement in proton--antiproton mass distribution have also been sighted. All these new states, which were not as predicted by theory, will provide fresh insight into our understanding of how the fundamental particles bind themselves to form nuclear matter. Apart from these, the B-factories with performance beyond expectations, are providing new data on various B meson decay modes, which will help understand the asymmetry between matter and antimatter. In addition, these experiments are capable of giving a glimpse of physics beyond the Standard Model (SM) of particles and their interactions. In fact, current observations already indicate the presence of such new physics.