Searching for Physics Beyond the Standard Model

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The ultimate goal of particle physics is to find the fundamental theory of "unification" that describes all the particles of the universe, and the forces with which they interact, in a simple and elegant way. A first step was made with the development of the Standard Model (SM), which explains essentially all experimental data to date. However, for many reasons, we believe that the SM cannot be the whole story -- there must be physics beyond the SM. The search for this new physics (NP) is the crucial problem in particle physics today. I have been involved in this endeavour for most of my career, and my proposed research program continues along these lines: to participate in the search for new physics. The Large Hadron Collider (LHC) at the particle-physics laboratory CERN (Geneva, Switzerland) has four experiments that are looking for signs of NP. While no direct signals of NP have been seen, i.e., no new, non-SM particles have been detected, one of the experiments, LHCb, has observed and confirmed several indirect hints of NP. That is, there are measurements of observables that disagree with the predictions of the SM, suggesting that there are virtual NP contributions to the processes. These indirect signals point to two different decays of the b quark in which NP might be present. There is also a longstanding anomaly in another observable, the muon anomalous magnetic moment. Finally, 27% of the energy of the universe is made up of dark matter (DM), i.e., new particles that interact only gravitationally. As the SM does not contain any DM candidates, the existence of DM is already proof of NP. The bottom line is that, at present, we have several experimental results suggesting where to look for the physics beyond the SM. In searching for NP, (i) we want to confirm that the experimental data does indeed provide clear evidence for NP, and (ii) if present, we want to identify the NP. To this end, it is necessary to propose NP explanations of the experimental results and suggest ways of differentiating competing explanations. It is also important to find new ways of searching for signals of NP. My research involves all of these approaches. Now, research in particle physics is purely curiosity-driven - we simply want to understand how the universe works. Knowing what the NP is will help in this regard, but will not lead directly to improvements for society. On the other hand, historically there have always been numerous technological advances related to the building of the colliders and detectors used to search for NP. The most famous of these is the World Wide Web, which was invented at CERN in the 1980s, and has led to the internet. There is also the training of highly-qualified personnel (HQP). Research in particle physics develops a set of problem-solving skills that can be applied in many other areas. For example, I know of HQP who are now working in teaching, computer science, finance, geography, forestry, oceanography, and medical imaging.