The First Two Years at the LHC

Date :From 2012-06-05 To 2012-08-10
Advisory committee :
Local coordinators :H.-J. He, C.-S. Li, T.-J. Li (Contact Person), C. Liu, M.-X. Luo, Jing Shu(Contact Person), Z.-G. Si,J.-M. Yang, S.-H. Zhu
International coordinators :J. Ellis, T. Han, Y.-P. Kuang, P. Langacker, T.-J. Li (Co-Chair), L.-T. Wang (Co-Chair), Y.-L. Wu, C.-P. Yuan

The Standard Model (SM) is a tremendous success of twentieth century physics. However, there are quite a few problems in the SM that motivate new physics, for example, the gauge hierarchy problem, the strong CP problem, the SM fermion mass hierarchies, the absence of gauge coupling unification, charge quantization, etc. In addition, there are convincing pieces of evidence for new physics beyond the SM, for instance, dark matter, neutrino masses and mixings, cosmic inflation, and dark energy. From the theoretical point of view, all of the gauge interactions might be unified into Grand Unified Theories (GUTs), and all the fundamental interactions in Nature might be unified in string theory. To understand the fundamental laws of the Nature, we need to test the new physics scenarios around the TeV scale, and try to probe the physics close to the Planck scale, in the current and future experiments.

The Large Hadron Collider (LHC) has been operating since March 30, 2010. At the moment, more than 1 fb−1 data have been collected by each of the two multi-purpose detectors ATLAS and CMS, with many participants from China and dozens of other countries. The machine and experiments continue to perform well. The SM has been “rediscovered”. For example, measurements of the W± and Z0 gauge bosons are consistent with expectations, as are those of the top quark, and b quark tagging is working very well. The shape of distributions for high energy jets and missing transverse energy are also in good agreement with Monte Carlo simulations. Operating at a center of mass energy of 7 TeV, the LHC has brought the field of High Energy Physics (HEP) to a new energy frontier. It is expected to at least reach an integrated luminosity of 2 or 3 fb−1 by the end of 2011 and perhaps 5 to 7 fb−1 by the end of 2012. This will enable us to explore directly large classes of new physics beyond the Standard Model at the TeV scale, an energy frontier at which new physics is strongly expected to appear. Needless to say, it is crucial and timely in 2011 to focus on implications of the early LHC data. Intensive studies have already been performed on new physics and their phenomenology at colliders, and much is being learned about how to interpret the signals of new physics.

The specific content of this program will naturally depend on the outcome of the early stages of the LHC operation, and its emphasis will certainly be on addressing whatever physics opportunities and challenges arise from LHC data. It could include detailed consideration of the Standard Model physics, discussions on potential indications of early discovery, as well as possible implications for theoretical models and further experimental studies. Potential areas to focus on include supersymmetry, GUTs, string phenomenology, Higgs physics, top quark physics, B physics, large extra dimensions and alternative approaches, keeping in mind related electroweak and QCD issues. We also note that there are many other experiments which will produce interesting results in the next couple of years, including neutrino physics, dark matter searches and measurements of flavor mixings and CP violation. While the main focus of our proposed program is on topics directly related to LHC data, the synergy of the LHC results with other experiments and measurements will also be considered. We would strongly encourage the participation of experimentalists. In addition, we shall organize a three-day conference associated with the program, with the time to be determined. Major LHC experimental collaborations have shown interest in participating and presenting their results. The program should lead to new research results and opportunities for fruitful collaboration. It will also provide a valuable venue for having pedagogical lectures.

Given the large impressive pool of the applicants from a broad base, we believe that this program will serve as a great platform to promote on-site research collaborations. With active on-going analysis of the LHC data, such a program will be of great benefit to the Chinese particle physics community in stimulating activity in these areas and in increasing connections to the international experts active in these areas. Such interaction and collaboration will not only be beneficial to Chinese physicists and their international colleagues, but also be scientifically important and help fill a gap compared to other areas of particle theory worldwide.