My research is in the broad area of theoretical particle physics.
I started in research in 1974, the same semester that the J/psi was discovered. I still remember the excitement of the project that this discovery stimulated and my first scientific paper which resulted. This discovery was a seminal event in particle physics and I have been fortunate to live through the subsequent development of the Standard Model. In a reflective moment, I have written an annotated summary of my career path. Today, when we are looking forward to evidence of the next layer of reality from the LHC, I am still excited by the prospects of uncovering new aspects of fundamental physics and of the opportunity for better understanding the nature of the physical world.
One of the advantages of a relatively long career is that one develops interests (and occasionally some expertise) in very many areas. My present research spans several of these areas. For example, since 2004, my papers have been posted on 5 different sections of the arXive.
Here is a feed from the arXiv that shows the abstracts neatly.
Here is the citation summary that lists the papers by their citation impact.
With Eugene Golowich and Barry Holstein, we wrote The Dynamics of the Standard Model. In 2014, we published a second edition. We have created a home page for the book, where you can find useful links, errata and extra features.
At the present, here are some topics that I am actively working on.
Effective field theory of general relativity
I retain a deep interest in the effective field theory of general relativity, the only known way to make reliable predictions of quantum gravity. Here is a link to a page on the effective field theory treatment of quantum gravity. With colleagues, we are starting some projects to understand the effect of the cosmological constant, the effect of quantum corrections on cosmology and the study of matter effects below the Planck scale.
Running couplings and gravity Mohamed Anber and I have two papers on this topic, for other couplings and for gravity itself. This is part of a larger program that we have in mind to start exploring the effects of gravity as it approaches the Planck scale. Of particular interest are the approach to asymptotic safety and/or classicalization.
Emergent gauge symmetry
I am trying to develop some research into the topic of the “emergence” of the fundamental physical laws. This was started under a grant from the Foundational Questions Institute. Here is a link to a page on the idea of emergent physics.
In addition to some phenomenology inspired by thinking about emergence, the studies have also lead to some new work on violation of gauge invariance and of general covariance, being done with Ufuk Aydemir, Mohamed Anber and Basem El-Menoufi. The first paper on this topic is published. A talk on the general program is also available. Other projects will be written up soon.
With the advent of the LHC, it is compelling to consider issues of physics beyond the Standard Model. I have had a recent paper on this with Mohamed Anber and others. Ufuk, Mohamed and I are also exploring the issue of when new physics must appear. The usual argument uses the tree level unitarity violation of the effective theory to predict the energy of new physics, but we note that this fails in the well known case of chiral perturbation theory because the theory ends up satisfying unitarity order by order in the energy expansion.
I am interested in tests of the Equivalence Principle and have written two papers on the topic with Thibault Damour. This project took far too long, but I am happy with the outcome.
Regge physics and effective field theory
The Soft Collinear Effective Theory (SCET) is designed to include the key physics at high energy, However, it does not incorporate Regge physics, which is THE leading behavior at the highest energy. I am interested in figuring out how this works.
Anthropic constraints and particle physics
I have explored some new ideas on likely values of the Higgs expectation value, with Koushik Dutta, Andi Ross and Max Tegmark . This work is now in the arXive. This is the most recent in a series of papers that have anthropic implications.
Here is a link to my academic genealogy. It goes back to Jacob Bernoulli, but stops there because he was self-taught.
In the other direction, here is a link to my Ph.D. students and their work.