Grant: Subatomic Physics Envelope - Project

It is now 40 years since Steven Weinberg published his seminal paper linking ElectroMagnetism and the Weak Interaction which led to the development of the ""Standard Model"" of particle physics. All the present data from accelerator experiments, aside from neutrino oscillations, can be explained by the SM but most physicists believe that there is a more fundamental theory beyond the SM since it contains more than 20 arbitrary parameters and it also predicts too small a value for the baryon number resulting from the big bang.The search for the Higgs boson, the fundamental particle which is supposedly responsible for the mass of all the other particles, is currently underway at the new 1B$ LHC at CERN. Some new particles are almost certain to be discovered during the next 5 years at this ""high energy"" frontier.However, there is another frontier, namely the ""precision"" frontier, which is also being actively pursued for new physics beyond the SM. Such precision experiments are complementary to the production experiments at the high energy colliders. Our TREK experiment, at J-PARC in Tokai, Japan is one such experiment. We are searching for a T-Violating transverse muon polarization (P_T) in K+ decay, This process is forbidden in 1st order in the SM and so a non-zero measurement would immediately indicate the presence of some new physics. Indeed, there are predictions from the triplet Higgs model and also various SUSY models which come close to reaching the current upper bound on P_T from our earlier experiment at KEK. We note that P_T is linearly sensitive to the amplitude of any new interaction which could interfere with the higher order SM processes rather than the square of the amplitude (which is the situation in the production experiments). Our experiment will upgrade our existing detector and use the increased beam intensity at J-PARC to gain at least a factor of 20 improvement in our measurement sensitivity which will validate one of the non-SM theories or at least significantly constrain the parameter space for any of the extended SM theories.