Global QCD Analysis and Precision Electroweak Physics in High Energy Collider Phenomenology

Michigan State University, East Lansing MI

Investigators

Abstract

This award funds the research activities of Professor C.-P. Yuan at the Michigan State University (MSU). This project will contribute to our understanding of the fundamental nature of the physical universe --- the particles that comprise the universe and their interactions --- as revealed through sophisticated experiments in high-energy physics. Our current understanding of this physics is embodied within the so-called Standard Model (SM). Protons, neutrons, and all other strongly-interacting particles are composed of fundamental particles called partons (quarks and gluons), and interactions between these partons are described by the theory of Quantum Chromodynamics (QCD). The proposed research involves the interplay between QCD theory and experimental data from many experiments, including recent experiments at the CERN Large Hadron Collider (LHC). This global analysis of data is necessary in order to deepen our understanding of QCD, and to determine the distributions of the partons in the proton. In particular, by understanding these distributions, it is possible to start with interactions of protons with protons (which are the interactions that actually occur at the LHC) and determine the underlying quark-quark, quark-gluon and gluon-gluon interactions. This is essential for determining the underlying physics of the process --- indeed, such information was necessary for extracting the signal for the recently-discovered Higgs boson from collider data. Support for this project is therefore in the national interest because it furthers the development of fundamental science in the United States and enables the extraction of important data from collider experiments in which substantial national investments have already been made. This project is also envisioned to have significant broader impacts since it will involve the training of students and postdoctoral fellows in theoretical high-energy physics both at Michigan State University and at summer schools held by the Coordinated Theoretical and Experimental QCD (CTEQ) collaboration. More technically, this research will focus on the development of CTEQ-TEA Parton Distribution Functions, earlier versions of which have already have been essential for the interpretation of data from the world's leading high-energy collider facilities such as Fermilab (Batavia, IL), RHIC (Brookhaven, NY), DESY (Hamburg, Germany), and CERN (Geneva, Switzerland). The proposed research will also continue to refine world-leading contributions to lepton-hadron and hadron-hadron collider phenomenology. Complementary to the research on QCD, the group will also study the Electroweak (EW) sector of the Standard Model (SM), which is extremely successful in explaining and predicting experimental data spanning a range in energy from the atomic scale to the Z boson, Higgs boson and top-quark masses. Measurements of the production of W's, Z's, top-quark pairs, single top quarks and Higgs bosons at the LHC, including both inclusive rates and relevant kinematical distributions, will provide major new input into our understanding of parton distributions during the next few years. At the same time, refinements of the parton distributions are necessary for progress in the EW sector, both for testing the SM at greater precision and for probing the effects of new physics at high-energy colliders.