Matthew Herndon

University of Wisconsin
Department of Physics
High Energy Experimental Group

Contact Information

Matthew Herndon:
Assistant professor of physics with the University of Wisconsin

Email: herndon@hep.wisc.edu

Phone Work(Wisc.): (608) 262-8509
Office(Wisc.) 4219 Chamberlin Hall

Phone Work(FNAL): (630) 840-2116
Office(FNAL) B0 Trailer 137-F

Research Interests

My research interests lie in the frontier of fundamental physics. High Energy Physics(HEP) offers some of the most interesting experimental opportunities to expand our knowledge of fundamental physics and discover new physics phenomena. I am primarily interested in studying the predictions of theories that pose solutions to the fundamental questions not answered by the Standard Model of particle physics. These questions include, but are not limited to: how to unify gravity with the other fundamental forces, baryogenesis and the prevalence of matter over antimatter in the universe, understanding the values of the large number of parameters in the Standard Model and an explanation for dark matter. An example of a theory that poses answers to some of these questions is the minimal Supergravity Unification Model(mSUGRA). mSUGRA offers a solution which unifies the ideas of Supersymmetry(SUSY) and gravity. Also in the mSUGRA variant of SUSY a small subset of the model's parameters describes a large part of the behavior of the model which gives the theory considerable predictive power. These predictions can be tested by collider physics experiments, which can either constrain the possible parameter space of the model or discover new physics predicted by the model.

I participate in the CDF Experiment at FermiLab Fermilab is home to the Tevatron which is the highest energy accelerator currently operating in the world. The one TeV(Tera Electron Volt) energy of the proton and antiproton beams of the Tevatron made the CDF experiment, which is located at one of the points where the protons and antiprotons collide, one of the most likely places in the world to find evidence for new physics. Soon the center of high energy physics will move to the CERN laboratory near Geneva Switzerland. There the LHC will achieve an energy 7 times than of the Tevatron. At the LHC I plan to work on the CMS detector.

The projects I'm working on at CDF and CMS include:

Analysis: My research interests lie in direct and indirect searches for new physics. New physics can either manifest itself in the form of new particles never observed before, or those same new physics particles could have subtle effects on the decays or other properties of particles we have already observed. Currently I am working on such analysis involving the Bs meson, a composite particle with a b quark and an anti s quark and searches for the Higgs boson.

The Standard Model of particle physics includes one major undiscovered particle known as the Higgs boson. Experimental evidence and the calculations in the framework of the Standard Model show a huge difference in the strength of the electromagnetic force and the weak force. This difference in strength is several orders of magnitude and manifests itself in the fact that electromagnetic decay interactions takes place almost instantaneously while the probability of some weak decay interactions is so low that they can take thousands of years or more. This fundamental difference is explained by the massiveness of the weak interaction bosons. Without the large mass of the weak bosons the electromagnetic and weak forces would have the same strength or be symmetric. The source of this electroweak symmetry breaking in the Standard Model is the Higgs mechanism which give mass the weak boson and other particles. This theory is directly testable by observing the Higgs boson making Higgs boson research one of the primary goals of modern particle physics. The Higgs boson interacts with other particles in proportion to their mass. At high mass, around 160-170GeV, the Higgs boson will decay primarily to W bosons, mass 80.4GeV. I'm involved in the high mass Higgs boson search at CDF. Our latest results results have achieved sensitivity to the Standard Model production rate for a high mass Higgs boson. If there were a Higgs boson in the mass range 160-170GeV we would expect to produce and observe a substantial number of Higgs bosons(approximately 16). Given that we observe no substantial signal we can rule out the production of the Higgs boson with a mass of 170GeV. This is the first direct information on the Standard Model Higgs boson since the final results of the LEP collider. These results where first presented at the the 2008 International Conference High Energy Physics, ICHEP. See my presentation here. We expect to rule out a large range of masses with the next version of this analysis including more data and updated technique.
Currently I'm also working on a search for Bs &rarr &mu &mu, which has resulted in the world's best limits on this rare decay. In the Standard Model of particles physics the probability for this decay is extremely small(on order one in one billion Bs mesons made will decay into two muons according to the Standard Model). However this decay indirectly probes for new physics since this decay might occur up to 1000 times more often in SUSY models such as mSUGRA. The results of this analysis are published in Physics Review letters. PRL 100, 101802 2008, PRL 95, 221805 2005 and PRL 93, 032001 2004
I just finished working on a first observation and measurement of the phenomena of Bs - Bs oscillations. This is a process via which a Bs meson can spontaneously convert itself into an anti Bs meson. One of the motivations of investigating this process was to try and understand why there is so much more mater than antimatter in the universe. The results of this analysis are published in Physics Review letters. PRL 97, 242003 2006 and PRL 97, 062003 2006.

Leadership

I am currently serving as CDF Higgs group leader. We expect our analysis to have the potiential to set limits on standard model Higgs mass in the region from the 100-200GeV. At high mass we have already achieved sensativity to Higgs boson production and have set limits on the mass of a SM Higgs boson. In addition we have sensativity to many non standard model Higgs posibilities.
See our public page for all the interesting results we are currently working on.
Previously served as CDF B group leader(2005 and 2006).
See our public page for all the interesting results we are currently working on.
Previously served as CDF tracking(2002 and 2004) and J/psi group(2004) leaders.

Tracking Software

Tracking software is the heart of a particle physics experiment. The "tracks" which are the paths of ionization of the particles left in silicon sensors and gas filled wire chambers allow you to measure the momentum of the particles formed in high energy collisions. Currently I am initiating a project to improve the performance of the forward track finding using the CDF silicon micro-vertex detector. Finding tracks in this region of the detector with high efficiency will allow the identification of forward leptons and significantly enhance the sensitivity of lepton based searches for new physics. Tracking using a silicon micro-vertex detector will also be the primacy method of finding tracks and leptons in the CMS detector and the ideas developed and tested at CDF will be applicable to at that experiment as well.

Selected Talks

Wiconsin Seminars and Colloquia

Teaching

Fall 2007: Physics 535 Introduction to Particle Physics
Spring 2007: Physics 103 General Physics(current course homepage)
Fall 2006: Physics 107 Ideas of Modern Physics
Spring 2006: Physics 104 General Physics(current course homepage)
Fall 2005: Physics 107 Ideas of Modern Physics

Previous Experience

From 1999-2005 I worked on the CDF Experiment at FermiLab

Tracking software: Tracking algorithms, Cluster finding, and Monte Carlo simulation
Silicon Detector construction and installation

From 1994-1998 I on the OPAL Experiment at CERN
The projects I worked on at OPAL included:

Monte Carlo software for the OPAL Hadron Calorimeter
Power supply and gas system expert for the Hadron Calorimeter
Analysis Search for the Bc Meson

From 1993-1994 I worked on R&D for a Time of Flight(TOF) system for Particle Identification at BaBar