Tony M. Liss
Professor of Physics
Professor Liss received his Ph.D from the University of
California, Berkeley, in 1984, after receiving a B.S. in physics from Johns Hopkins University in 1979. He was a postdoctoral research associate
at the University of Chicago from 1984 to 1988, when he joined the Department of Physics as an assistant professor. He was promoted to associate
professor in 1994 and to professor in 1998.
Professor Liss is an experimental high energy physicist whose research probes the fundamental nature of matter at very high energy and at very small distance scales. He has carried research at the Fermilab National Accelerator Laboratory (FNAL) since 1984. The FNAL "Tevatron" provides counter-rotating beams of protons and antiprotons that collide with a center of mass energy of 1.96 TeV, currently the world's highest available energy source. Professor Liss is a leading member of an international collaboration, the Collider Detector at Fermilab (CDF) collaboration, which has built and operated a large multi-purpose particle detector (the CDF detector) at FNAL. He served as the convener of the Top group at FNAL and was one of the leaders of the analysis for the discovery of the top quark. He was the Physics Coordinator for CDF for 2002-04.
During a sabbatical in 1998/99, Professor Liss explored an entirely new field—the Antarctic Muon And Neutrino Detector Array (AMANDA)—a detector then under construction at the South Pole, whose purpose is to observe high-energy (~ 1 TeV or 1012 electron volt) neutrinos from astrophysical point sources. Strings of widely spaced photomultiplier tubes (PMTs) were placed deep into water-drilled holes in the South Polar ice cap. High energy neutrinos coming up through the earth occasionally interact with ice or rock and create a muon; such a muon emits Cerenkov light when passing through the array, and it can be tracked by measuring the arrival times of these Cherenkov photons at the PMTs.
Research Areas: experimental particle physics, production and decay of the top quark, Collider Detector at Fermilab
Description of Current Research
Elementary Particle Experiment
The two main thrusts of elementary particle physics research are to determine the form and strength of the fundamental
interactions in nature and to determine the properties of the particles that enter into these interactions. Our group
presently works on experiments at Fermilab, Cornell University, and CERN. We participated in the discovery of the top
quark and the first observatoin of time reversal symmetry violation in B-meson decays. We are involved in the precision
study of top, bottom and charm quarks and searches for physics beyond the standard model.
Collider Detector at Fermilab
The superconducting particle accelerator at Fermilab is used to store beams of protons and antiprotons at
980 GeV, the world's highest energy. The CDF group has built a large detector to investigate the nature of
the interactions that occur when these beams collide head-on. Precise measurements of the properties of the
W boson, top quark, and other elementary particles are being made.
Selected Publications
Acosta, D, et al. (CDF Collaboration). Measurement of the tt-bar production cross section in pp-bar collisions at √s = 1.96 TeV using lepton + jets events with secondary vertex b -tagging. Phys. Rev. D 71, 052003-1-28 (2005).
Acosta, D, et al. (CDF Collaboration). Measurement of partial widths and search for direct CP violations in D 0 meson decays to K–K+ and p–p+. Phys. Rev. Lett. 94, 122001-1-12 (2005).
Acosta, D, et al. (CDF Collaboration). First measurements of inclusive W and Z cross sections from Run II of the Fermilab Tevatron collider. Phys. Rev. Lett. 94, 091803-1-7 (2005).
Acosta, D, et al. (CDF Collaboration). Measurement of the moments of the hadronic invariant mass distribution in semileptonic B decays. Phys. Rev. D 71, 051103-1-9 (2005).
Acosta, D, et al. (CDF Collaboration). Measurement of the lifetime difference between Bs mass eigenstates. Phys. Rev. Lett. 94, 101803-1-7 (2005).
Abulencia, A, et al. (CDF Collaboration). Search for Bs0 m+ m– and Bd0 m+ m– decays in pp-bar collisions with CDF II. Phys. Rev. Lett. 95, 221805-1-7 (2005).
For the public:
T. Liss & P. Tipton, THE DISCOVERY OF THE TOP QUARK , Scientific American, September 1997.
Research Contributions
Proposed, designed and built the Central Muon Upgrade (CMUP), a very large array of drift chambers that surrounds the CDF detector and significantly improved the detection of muons in the central region. It performed flawlessly in the 1992-93 data-taking run and was a key element in the discovery of the top quark. The CMUP system has also proven to be invaluable for bottom quark physics and for another key measurement, the mass of the W boson.
Took a lead role in the CDF "Evidence for Top Quark Production" paper, which was published in Physical Review D in 1994. Professor Liss was convener of the top group during this time, organized much of the analysis, and did a significant amount of it himself. In particular, he performed the non-trivial calculation of the 'significance' of the result--a number which expresses the probability that the observation is from background only--and indeed determined whether or not the top quark had been "discovered."
Measured the cross section for top-antitop production. This measurement extends his previous publications on the subject with significantly more data and new techniques.
Measured the helicity of W bosons from top decay, a test of the standard model coupling at the tWb vertex.
Served as the first CDF Physics Coordinator for two years (2002-2004) and in this role oversaw the physics analysis of several hundred CDF collaborators.
Honors and Awards
- Fellow, American Physical Society
- University Scholar, University of Illinois
- Arnold O. Beckman Award, University of Illinois Center for Advanced Study, 1988
- Fellow, Alfred P. Sloan Foundation
- Beckman Associate, University of Illinois Center for Advance Study, 1995–1996
- Xerox Award for Faculty Research, University of Illinois College of Engineering, 1997