Michael Schmitt

Research Areas


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Student Research Positions: I am looking for enthusiastic and hard-working undergraduates to work with me. I am also looking for future graduate students. If you would like to contact me about working in my group, send email to:
m-schmitt@northwestern.edu
Postdoc Research Positions: I am looking for a postdoc to work with me on Mu2e. (Note: it is possible for a postdoc to also analyze CMS data.) If you would like to join my research group, send email to:
m-schmitt@northwestern.edu


Particle Physics at Colliders

My main collider physics research area is the production of W and Z bosons in high-energy proton-proton collisions. I am a member of the CMS Collaboration.

W and Z bosons are produced singly, in pairs or even in triples. They are most easily detected through their decays to charged leptons. My group has worked with muons for many years. The standard model provides a solid foundation for predictions of the cross sections for W and Z production. My group tests those prodictions in new and novel ways, with the goal of identifying failures that point to the need for improved calculations or to signals for new physics.

My group is pursuing (at least) three important topics: (1) The measurement of the WW cross section, which earlier had hinted at new physics. We have deployed a novel and highly effective classification technique based on random forests. (2) The search for evidence of WWW production, which is predicted in the standard model and which is highly sensitive to anomalous quartic couplings. (3) The precise measurement of the Z branching fraction to four leptons, which is sensitive to new light gauge bosons that couple primarily to muons.

CMS public page at CERN

 


Lepton Flavor Violation

I am a member of the Mu2e Collaboration that will conduct a new experiment at Fermilab over the next decade. This experiment will search for the conversion of muons into electrons in the field of an atomic nucleus. Such conversions would violate both muon and electron number, and are highly suppressed in the standard model. The observation of muon to electron conversion would be a major breakthrough in particle physics.

Muons are produced by directing a proton beam onto a fixed target. These muons can be captured by atoms where they usually undergo muon decay, characterized by a low-energy electron and two neutrinos that escape direct detection. If the muon converts to an electron with no neutrinos, then the electron will have a relatively high energy. The experiment searches for such anomalous electrons. If none are seen, then the upper limit on this process will be improved by a factor of 10,00 over the existing limit.

My group is responsible for a representation of the full magnetic field that must be accurate at the 10-5 level in the detector solenoid. This is a challenging mathematical and programming task as the field is highly inhomogenious. A poor representation will compromise the sensitivity of the experiments because it will lead to a worsening of the electron momentum resolution.

We also carried out a careful estimate of the background coming from pions scattering in the stopping target (the target that absorbs the muons) and of unwanted magnetic bottles that could lead to dangerous backgrounds.

We are interested in the forbidden process μ-→e+ (the charge of the nuclear also changes).

Mu2e Home Page at Fermilab

 


Advanced Data Analysis Methods

My group places a major emphasis on advanced analysis techniques. We try to tackle problems and pursue uncommon ideas that could make a difference in the way particle physics data are analyzed in the future. Some but not all of our work is published in stand-alone papers, i.e., papers not co-authored by the CMS or Mu2e collaborations.

Recent examples of this work include a paper on using the Bayesian Blocks algorithm for histogramming (InSpire), Minimal Spanning Trees in particle physics (InSpire), and the application of random forest classifiers for isolating a sample of W+W- events in CMS data (InSpire). This last study is coming to fruition in the measurement of the W+W- cross section with CMS data, and also the jet multiplicity distribution.

 


Supernovae Studies

The discovery of dark energy hinged on the use of supernovae as "standard candles" that could be used to gauge distances accurately. Little is known about dark energy and better measurements of the expansion of the universe are imperative.

Supernovae, however, are not well understood. Large samples will be collected by current intruments and by the LSST in the future. I am preparing to join the LSST Collaboration in order to contribute to supernovae studies and to help understand the expansion of the universe.

The key feature of a supernova is its light curve, ie, the way its brightness rises and then falls slowly. My group is working on a representation of supernova light curves based on artificial neural networks. We also hope to look for anisotropies in the distributions and properties of supernovae.

LSST Home Page

 

 


Misc.
Collider Blog - a particle physics blog that I write occasionally

 

 

Last modified: Sun Sep 23 11:01:46 CDT 2018