Abstract
Dark matter contains 85% of the matter density and it is supposed to have a rich structure, same as our complex baryonic world. The dark sector related with the 85% matter density, is defined as particles which do not interact strongly with the Standard Model particles. It contains dark matter as a stable particle, and particles mediating interaction
between dark matter and visible sector. Such particles are called dark mediators, whose interaction with visible sector is feeble, thus could be long-lived. We go over the direct, indirect and collider searches for the canonical dark matter candidate, the weakly interacting massive particles. Then we focus on the recent phase-2 upgrade of the LHC detectors, which has generally planned a timing resolution of 30 ps. We demonstrate that with the timing upgrade of the LHC, it can improve the sensitivity for the long-lived particle searches significantly, comparing with the traditional displaced-vertex methods. Besides the canonical dark matter candidate, we briefly introduce the ultralight dark matter phenomenology, emphasizing an interplay with neutrino physics and a possible solution to small structure problem.
