Elementary Particle Theory

Cornell University, Ithaca NY

Investigators

Abstract

This award funds the research activities of Profs. Csaba Csaki, Yuval Grossman, Toichiro Kinoshita, Peter Lepage, Liam McAllister and Maxim Perelstein at Cornell University. The investigators propose to study some of the most important and exciting topics in a variety of fields within high-energy theory, including particle physics in and beyond the Standard Model, collider physics, string theory, and cosmology. Research on the Standard Model (SM) consists of investigations of flavor and neutrino physics, lattice quantum chromodynamics (QCD), and precision quantum electrodynamics (QED). Beyond the Standard Model, explorations of diverse models of the TeV scale are proposed, together with studies of the new collider physics techniques necessary for testing them. Investigations of aspects of dark matter physics are also proposed. Within string theory the primary focus is on understanding the effective theories arising in string compactifications, and exploring the implications of string theory for cosmology. Intellectual merit: The Cornell particle theory group carries out state-of-the-art research in nearly every major area of modern particle theory. The unifying theme of the group's research program is a distinctive focus on theoretical problems that are relevant for present and future experiments, including the Large Hadron Collider (LHC), the intensity frontier program, dark matter searches, and cosmic microwave background experiments. The proposed research is directed at maximizing the scientific impact of these experiments. The most important recent development in particle physics is the historic discovery of the Higgs(-like) boson, as part of the wealth of data produced by the 2010-2012 runs of the LHC. Professors Csaki, Grossman and Perelstein will focus their attention over the next five years on physics related to current and future colliders. Csaki will explore unconventional supersymmetric models that are still viable in light of the LHC data; alternative Higgs models, including a Higgslike dilaton and the composite Higgs; and other TeV-scale models consistent with LHC results. Grossman will explore the physics that is relevant to the intensity frontier program in the near and more distant future. This includes charm and beauty physics, charge-parity (CP) violation, and the study of neutrino physics. Perelstein's research plans include using the new window on TeV-scale physics provided by the 125 GeV boson to glean new information about possible physics beyond the Standard Model; understanding the implications of the direct LHC searches for new physics, focusing in particular on naturalness issues; and proposing new LHC searches motivated by both theoretical and experimental developments. In parallel, Perelstein proposes to continue to contribute to theoretical interpretations of dark matter searches, where several interesting hints of detection have already been reported, and much more data will soon become available. Professor Lepage, as a leading member of the "High Precision QCD" (HPQCD) lattice gauge theory collaboration, will continue the pursuit of high-precision results for heavy quark physics from lattice gauge theory, obtaining semileptonic D-meson form factors for charm physics; extending b-quark results to the same precision (of order 1%) as the charm observables; and determining the quark masses and the strong coupling constant to high precision. Professor Kinoshita has devoted the past decade to a systematic evaluation of the five-loop QED contribution to the anomalous magnetic moment (g-2) of the electron. In the next few years, he proposes to improve the numerical evaluation of his group's analytic results. Professor McAllister plans to investigate the physics of the very early universe, using cosmological observations of ultraviolet-sensitive quantities to shed light on theories of quantum gravity. McAllister's primary focus will be understanding inflationary dynamics in compactifications of string theory, but he also proposes to study the vacuum structure of non-supersymmetric string compactifications. Broader impact: The Cornell particle theory group puts a high priority on the training of graduate students and postdocs, as well as on the wide dissemination of recent research results to the general public. Over the past three years, the group graduated twelve students, a majority of whom are now postdocs, while eight of our former students who graduated over the past decade now have faculty positions in the U.S. or abroad. Every member of the group is vigorously pursuing all possibilities for outreach to the general public. Numerous public talks, articles, colloquia, high school lectures and teacher conferences have been produced in the past, and will continue to be organized in the future by the group members.