Dark matter and new physics

Date :From 2011-09-21 To 2011-11-06
Advisory committee :
Local coordinators :Xiao-Jun Bi(IHEP), Kai-Xuan Ni (SJTU),Chang-Gen Yang (IHEP), Qian Yue (Tsinghua U.),Yu-Feng Zhou (ITP)
International coordinators :Elena Aprile (Columbia U., USA),Katherine Freese (Michigan U, USA),Cristiano Galbiati (Princeton U. USA),Chao-Qiang Geng, (NCTS),Shigeki Matsumoto (IPMU, Japan ),Qaisar Shafi(Chair, University of Delaware, USA),Shu-Fang Su ( Arizona U. USA),Henry Tsz-king Wang (IOP-AS),John Wefel (Louisiana State U., USA)

 The discovery of dark matter is of fundamental importance to the present-day particle physics and cosmology. Numerous observations such as the rotational curves in galaxies, the gravitational lensing of galactic clusters, the WMAP measurements and the studies of large scale structures of the universe have indicated that nearly 23% of the energy density of our universe is made of non-baryonic cold dark matter, while only 4% is made of ordinary baryonic matter. The origin and the nature of dark matter, however, remains largely unknown, which is a great challenge of our time. From particle physics point of view, it definitely requires new physics beyond the current standard model of particle physics.
 
Great experimental efforts have been made for detecting and exploring the nature of dark matter. At present there are more than twenty ongoing underground experiments designed for direct detection of signals from dark matter 1 scattering off nuclei such as CDMS, XENON, DAMA, etc.. Different target nuclei and detection methods have been adopted to gain confidences to control systematic uncertainties. Meanwhile, A number of satellite-borne and balloon-borne detecters are also in operation, aiming at detecting the indirect signals such as cosmic positrons, anti-protons and gamma-rays possibly emitted from the dark matter annihilation or decay processes.
 
With the help of advanced experimental facilities, rapid progresses have been achieved in improving the sensitivity of the dark matter detection in both direct and indirect detections. Recently, the PAMELA experiment indicated a sharp upturn in the positron fraction in the cosmic rays, which is not expected from the standard astro-particle physics. The balloon-borne experiment ATIC-2 reported large excess of the total flux of electrons and positrons in a range of 300-800 GeV with a sharp cut-off at around 600-800 GeV. The latest Fermi-LAT results did not confirm the ATIC results on the excesses, but still indicate a spectrum harder than the expected backgrounds. The underground experiment DAMA/LIBRA has shown indications of an annual modulation of signals consistent with what might be expected from the dark matter nuclei scattering, while other experiments such as CDMS and XENON gave improved upper bounds of the elastic scattering cross section at the order of 10−44cm2. Very recently, the new results from CDMS-II and CoGeNT showed possible dark matter scattering events, which needs to be further examined by future experiments.
 
In the next few years, new generation of experiments such as AMS02, Ice- Cube, etc. will provide us more accurate information on the cosmic positrons, anti-protons, neutrinos, and gamma-rays, etc. in broader energy ranges. The underground direct detection experiments are going to improve the sensitivity by 1-2 order of magnitudes, which will touch the main bulk of the parameter space of many WIMP models. The running of the Large Hadronic Collider (LHC) will also shed lights on the dark matter detection.
 
 For the aspect of direct detection of dark matter in China, a few domestic universities and institutes such as the Institute for High Energy Physics (IHEP), Purple Moutain Observatory (PMO), TsingHua University (THU) and Shanghai Jiaotong University (SJU) have joined DarkSide, DAMA, ATIC, KIMS, TEXONO and XENON Collaborations to pursue the experimental studies for many years. THU has accumulated rich experiences on technologies includ- 2 ing ultra-pure CsI crystal detector and Ultra-Low-Energy HPGe detector. More theoretical supports are definitely needed for the further development of dark matter experimental search.

Recently, a promising site for the possible construction of a deep underground laboratory of China has been identified, which is an exciting progress related to the dark matter direct detection in China. Several universities and institutes are pushing forward to establish the national underground laboratory, and several experiments have already been proposed in 2009. We think that the first dark matter experiment of China will start in one or two years paralleling with the successful operation of the China-owned underground laboratory. The KITPC program may provide a good opportunity to introduce Chinese experimental plans of dark matter detection to the international community, and the discussions among the scientists will contribute to define the future scientific programs of the underground laboratory.
 
Given the rapid progresses in this research field, we find it timely to propose a KITPC program on dark matter and new physics at 2011. At that time, new exciting experimental results are expected to come out. The aim of the proposed program is to bring together world experts working at the interfaces of dark matter detection, dark matter theory, particle physics and cosmology. Topics of interest will include the implications of the recent space/underground experimental results, the mechanisms for the origin and annihilation/decay of dark matter, and new dark matter models from the particle physics beyond the standard model. We hope that the program will stimulate the theoretical and experimental advances in dark matter and new physics study.
 
The KITPC workshop will also host the seventh international workshop "Dark Side of the Universe (DSU 2011)" from September 26-30. DSU 2011 will be a continuation of DSU workshops previously held in Seoul (2005), Madrid (2006), Minnesota (2007), Cairo (2008), Melbourne (2009) and Leon (2010)". Topics covered during the DSU workshop will include dark matter, dark energy, inflation, and the interplay of particle physics, astroparticle physics and cosmology.

We hope that the program and the workshop will push forward the study of the dark matter detection experiments in China including both space and underground experiments, which has been initiated recently by the domestic community. We believe that this program will foster a stronger collaboration between the international and domestic scientists and bring up a new generation of young researchers that are well informed of the latest development of this research field.