Reinhard Schwienhorst

I am currently working as an Assistant Professor at Michigan State University. You can find more information about me on my MSU home page. I am a member of the HEP group at MSU, working on the DØ experiment at Fermilab and on the Atlas experiment at Cern. I am interested in top quark physics and in particular the production of single top quarks, both at the Tevatron at Fermilab and the LHC at Cern. At DØ I am working in the Top Physics group. I have also worked in the trigger studies group and on the Level 2 trigger.

Tevatron Collider Physics

Single Top Physics

Single Top Quark Physics at DØ

I am involved in many studies of single top quarks at DØ, the evidence and observation analyses and several searches for new physics in the single top final state.

We discovered single top quark production in 2009! The observation PRL paper and much more information can be found here. I was co-convener of the group, responsible for the statistical analysis and the discriminating variables, and was involved in many other projects like triggers or selection cuts.
With the observation dataset, cuts, and multivariate methods we also separated out the t-channel mode of single top production for the first time.
We combined the single top observation results from CDF and D0 within the Tevatron Electroweak Working Group.
We set the first direct limits on top quark anomalous couplings using single top final state information. We then combined the single top anomalous couplings result with the W helicity analysis in top quark decays for the most stringent limits on anomalous top quark couplings.
We found evidence for single top quark production in 2006. I was responsible for the statistical analysis and worked on the triggers and the multivariate methods, in particular the discriminating variables.
I searched for new heavy bosons W' that decay to a top quark and a bottom quark. This is the same final state as the single top s-channel and I used that data sample to look for a resonance peak in the final state invariant mass distribution. I didn't find any signal but was able to set tight limits on the W'. The paper can be found here.
I won the 2005 Tollestrup award for my postdoc work on single top at DØ! A video of the award ceremony, including the talk I gave can be found here. Images are in this folder. High-resolution images are available from Fermilab Visual Media Services or directly here.
Between September 2003 and July 2005 I was the co-convener of the Single Top working group at DØ. We have completed a search for single top quark production in the s-channel and t-channel using 230pb^-1 of data collected with the DØ detector at the Fermilab Tevatron. We have set upper limits on the production cross section that are a factor two better than any previous limits.
Our result is documented on the single top public result web page and has been published in Physics Letters B. We are also working on a longer, more detailed article to be published in Phys. Rev. D, which will contain both this neural network result and a cut-based result.

Single Top Phenomenology at Next-To-Leading Order

I am collaborating with Michigan State theorists C.-P. Yuan and Qing-Hong Cao as well as with fellow experimentalists Chip Brock and Jorge Benitez on studies of single top quark production at next-to-leading order in QCD. We have published a paper on s-channel phenomenology and a paper on t-channel phenomenology at the Tevatron.

Top Quark Physics at DØ

I am involved in the Top Physics group at DØ, focussing on Top Triggers and the Search for Single Top Interactions.
Between September 2007 and 2009 as well as between September 2003 and July 2005 I was co-leading the Single Top working group (DØ internal). Between September 2002 and September 2003 I was leading the Top Trigger working group.

We presented a comprehensive search for single top quark production for the Winter 2005 conferences, using three different analysis methods based on the same dataset: cuts, neural networks, and decision trees. The neural network result has been published in Physics Letters B.
We presented a first preliminary result for the Summer 2004 conferences.
My own outdated top quark physics page with some single top quark information that I have collected (DØ internal).
The Top Triggers page (DØ internal).

L2 Trigger at DØ

I was in charge of commissioning the L2 trigger system beginning in September 2000. The L2 system started making trigger decisions in May 2002. I was also in charge of the L2 online system and L2 operations between May 2002 and September 2003. In these roles, I contributed to many different aspects of the L2 trigger, working on commissioning the hardware and software and everything associated with triggering at Level 2.

Some of the areas I have worked on are
- The L2 online web pages contain information on how to keep L2 running, including a tutorial.
- The L2 monitoring web pages have information on L2 monitoring software and display graphics.
- The L2 teststand web pages for those who want to test boards or algorithms.

Other Activities at DØ

From 2009 to 2010 I am low-mass Higgs working group co-convener.
I have put the ONETOP MC generator into the DØ software environment.
As a member of the DØ trigger board I have worked on tools to understand trigger rates and coordinate large trigger lists. I have in particular looked at trigger overlap and unique trigger rates.

Neutrino Physics

DONUT

Before starting at DØ I did my thesis work on the Donut experiment. We were the first (and so far only ones) to see tau neutrino interactions. We used a beam enhanced in tau neutrinos and photographic emulsion to identify the tau lepton produced in the interaction. My thesis was on the search for a tau neutrino magnetic moment and the result was published in Physics Letters B. More details about Donut at the University of Minnesota can be found on this page. The Donut experiment announced the discovery of the tau neutrino in July of 2000.

Other Neutrino Studies

At the beginning of my graduate carreer I worked on the MINOS experiment, testing various scintillator options and phtomultipliers.
I did a study of colliding the neutrino beams associated with a muon collider and thet physics taht could be done with them.

Other Information

The DØ experiment.
Michigan State University Physics.
My page for Mandrake Linux on a Dell Inspiron 5100 Laptop, Mandriva on a HP/Compaq nx6110 laptop, Mandriva on a Dell Latitude D820 laptop, Kubuntu on a IBM Thinkpad T60 laptop, Kubuntu on a IBM Thinkpad T61 laptop.
Resources for video and audio conferencing.

Maintained by Reinhard Schwienhorst and always under construction.