There is intense activity in the search of glueballs, light hybrids and multiquark states, either as supernumerary states with ordinary quantum numbers JPC, or as genuine exotics with JPC that cannot be matched by ordinary quantum numbers. In particular, evidence has been found for 1-+ states between 1 and 2 GeV by VES at Serpukhov, by E852 at Brookhaven, and by COMPASS at CERN, and the search continues at JLab by GLUEX. The structure of these states are still ambiguous. Four-quark states and hybrid states are the most possible explanations. To study these non-qq resonances beyond the conventional quark model, the Wilson coefficients of dimension-8 condensate contribution to the current-current correlator of 1−+ light hybrid current gq(x)γνiGμν(x)q(x) are calculated. With inclusion of these higher-power corrections and updating the input parameters, the mass of the 1−+ light hybrid meson are re-analyzed from Monte-Carlo based QCD sum rules. In this talk, the basic idea of the quark model and QCD sum rules will be briefly reviewed and then the results of calculation and numerical analysis will be presented.
Abstract: The majority of matter in the universe is nonluminous and of unknown composition. It has been dubbed ‘dark matter’ for these reasons. The dark matter problem is one of the most pressing problems in both particle physics and astrophysics. This talk will provide an overview of the study of dark matter from a particle physics perspective. The evidence for the existence of dark matter will be reviewed, and the motivations for particle models of dark matter will be discussed. The talk will conclude with a description of experimental and observational searches for dark matter, including nuclear recoil searches, cosmic ray signals, and production in particle colliders.