This proposal requests continuing support for a program of research for the Brock/Abolins group at Michigan State University (MSU) in experimental elementary particle physics based primarily on the D0 experiment at the Fermilab Tevatron collider and the ATLAS experiment at the Large Hadron Collider (LHC) at CERN.
For the past few decades, physicists have been able to describe with increasing detail the fundamental particles that make up the Universe and the interactions between them. Much of this success has been due to the Tevatron program at Fermilab with D0 and CDF making major contributions.. This MSU group has made major contributions to the D0 experiment in its construction and in the physics questions proposed as well as in many leadership roles. Currently, the group is investigating the single top quark production mechanism which is sensitive to possibly new physics beyond the Standard Model. It participated in the initial measurements of the production rate a measurement many consider the single most important result from the Tevatron program. At the same time the LHC and ATLAS will start operation in new regimes of energy and luminosity holding even greater promise for discoveries and measurements leading to revisions of our views on how the world is constructed and the nature of the laws that govern its operation. This group is now transitioning into the ATLAS program where it will parlay its wealth of experience in single top physics into a leadership role in a similar study as well as other areas such as construction of trigger algorithms and installing trigger supporting hardware and its supporting infrastructure. In addition, MSU and the University of Michigan are building a new Tier 2 computing center and faculty research efforts will be directed in part to management and usage of this facility.
On Broader Impacts, the group will continue its work primarily within the QuarkNet program as well as an innovative non-science student honors course emphasizing Elementary Particle Physics and Cosmology and a course on modern physics for the Division of Science and Math Education during the summer term which typically draws ~20 high school teachers. Science Days and permanent exhibits in an atrium setting at MSU related to the ATLAS program are planned.
Elementary Particle Physics is the study of the most fundamental quanta in the universe and the forces that act among them. These quanta are referred to as "particles" but their natures are actually complicated quantum mechanical entities with masses, electric charges, spins, and other defining characteristics. It is particularly interesting to imagine the nature of our universe in its earliest stages, micro-micro seconds after the Big Bang when all particles that Nature can produce, would have been produced naturally–just once. We reproduce those conditions in accelerators by colliding high energy beams of particles and studying the particles which are produced and their interactions which tells us what this earliest time must have been like and also helps us understand how we must have evolved from this hot, primordial state. Of particular interest are three kinds of particles, one of which we know exists, one of which we expect exists, and one of which is hypothesized to exist. We know that the heaviest of the six known quarks, the top quark, is atrociously massive and is normally produced in pairs when protons and antiprotons (or protons) collide. This was the discovery mechanism at the Fermi National Accelerator (Fermilab) in the 1990's. However top quarks were expected to be produced one at a time through a different mechanism. Were that to be the case, parameters of importance to the whole quark story could be extracted from measuring the properties of "Single Top" production and decay. Searching for this mechanism has been a focus of our research for many years. In 2010 our group was prominent in the discovery of this reaction with one of our faculty leading the DZero experiment's Single Top Group and one of our graduate students' thesis topic was the actual discovery. We have since taken our expertise in this subject to our experiment at the LHC, ATLAS, where one of our faculty leads the Single Top Group there. We have three more graduate students working on this subject at the LHC. Essential to our understanding of the Standard Model of Particle Physics is the Higgs Boson, the quantum of the field that is thought to be responsible for the mass of all elementary particles. There is little theoretical guidance as to the mass of the Higgs Boson and so the search has been entirely experimental by both directly narrowing the window of mass, or indirectly by boxing in its expected mass by measuring other quantities that are related through the theory. Our group has been in the leadership of the Higgs Boson search in the DZero experiment at Fermilab as well as in the combination of all 12 channels in which the Higgs Boson might manifest itself in both the DZero and CDF experiments. The results are enticing as the mass range allowed for this long-sought-after particle is narrowing as a result of our work at the Tevatron. This is in phase with the direct searches at the LHC as well. Two graduate students and a post doc are working in our group to narrow down the Higgs Boson search at DZero. Finally, all forces in nature are propagated by "Messenger Particles" that transmit the influence from matter particles and neutrinos to other particles. The most familiar Messenger Particle is the photon, which transmits the electromagnetic force. Less well appreciated are the W and Z bosons which transmit the weak force, and in the case of the Z, also a mix of the electromagnetic force. We know of one Z boson at the present time, but extended theories beyond the Standard Model hypothesize additional Z bosons and our group at the ATLAS experiment at CERN is searching for additional Z as well as W bosons by various means. The higher energy of the LHC makes it possible to search far beyond the limits set by the Tevatron. Our group specializes in electronics for particle physics experiments and we have built many racks of sophisticated electronics for the DZero experiment at Fermilab. We have extended this expertise to the LHC where we are working with groups in Britain, Sweden, and Germany to augment the electronics of the ATLAS experiment as well. We likewise specialize in high-density computing and have for many years been a major contributor to the "grid-based" computing cloud for DZero and more recently as a Tier 2 Computing center for US ATLAS. We are always searching for ways to bring the results of our research to the general public through talks, evening classes for adults, and most recently a plantarium show written by and produced by our faculty and students.
