Home Page of Steve Ellis
Classes to be taught during 2013-14 academic year
Spring Physics 226
Materials from Autumn-Winter 2012-13 Physics 557-8
BOOST 2011: the Rick & Steve Show
Lectures elsewhere -
Talk on Benchmarks for Jets at Benchmarks Workshop, November 19, 2010
Seminar at LPC/Fermilab, November 18, 2010
Talk at Manchester Workshop, November 2, 2010
US ATLAS Final State Forum, 8/23/10, Lecture on Jet Algorithms
2010 CERN Summer Programme, Lecture on Jets, July 9, 2010
History Talk at BOOST 2010, June 22, 2010
Seminar at Cavendish Lab, 6/17/10
Maria Laach 2008 QCD Lectures
PiTP 2007 SM (Colliders) Lectures
QCD Lectures for TRIUMF Summer Institute (TSI) July 06
Other UW links
Web Page for past Particle Physics Courses: Physics 557-9
Web Page for past Math Physics Courses: Physics 227-8
Not so Recent Talks:
Photos of UW activities
Visitation Weekend 2007 - Photos
Visitation Weekend 2005 - Photos
Awards Dinner 2004 - Photos
Visitation Weekend 2004 - Photos
Jet Review Paper Final Draft
Les Houches, May 2005
TeV4LHC Brookhaven, February 2005
TeV4LHC Fermilab, September 2004
1. Talk at QCD/CDF/Theory Jet Workshop at Fermilab, 12/16/02 (PowerPoint file, HTML file, click on animations to start them – if they don’t start automatically). Note that the HMTL version is pretty slow over the NET due to the (huge) AVI files for the animations (there is always a price for new technology). It may be better to download either the ppt file or the HTML file with the associated directory of graphics (located here) and run them locally.
3. Talk at Run II Jet Workshop, Fermilab, 1/23/02 (htm file from PowerPoint)
5. Run II Jet Workshop, Fermilab, 2/8/01 (does not include all figures)
6. Summary Talk at IPPP Workshop on Matrix Elements and Parton Showers, St John’s College, Durham, UK, 12/13-12/15/00 (PowerPoint)
7. Building Better Jet Algorithms, talk to CDF (4/7/00) and MSU (6/19/00), (does not include all figures)
Draft manual for ME-PS issues
Here are some Flash “movies” illustrating how the kT algorithm combines calorimeter cells, i.e., the movies illustrate the order in which cells (of size 0.1 x 0.1 in a symmetric region around the 2 partons indicated by the contours) are clustered (contiguous cells of the same colors are in a single cluster; the same color can be used by more than one cluster). These are all for the case of large smearing (s = 0.25) with varying values of z, the ratio of the ET’s of the 2 partons, and d, the separation of the 2 partons. First consider the case z = 1.0 and d = 0.71 (all with R = 0.7), which illustrates the generic behavior that the first cells to be clustered are at the periphery and that the clustering tends to grow inward along radial boundaries. This inward growth continues, with only a small amount of clustering in the angular direction, until all of the cells are in a cluster. The final stage involves the clustering in the angular direction, which in the next-to-final step yields 2 clusters with essentially the kinematics of the initial 2 partons. Thus if the 2 partons have d > R, there are 2 final jets (as in the movie). If d < R, there is one final jet. For a very asymmetric situation, z < 0.2, the final stages are more irregular and the partons must be further apart to avoid completer merging. These is illustrates by movies for z = 0.1, d = 0.8 (1 final jet) and z = 0.1, d = 0.9 (2 final jets).
Here are some notes (9/20/02) on the issues of kinematics and jet definitions in PDF format with figures.
Here are some recent (9/3/02) figures concerning the structure of stable cones in the (d,z) plane (the subscripts refer to whether stable cones are centered over the parton at the origin = L, at d = R, or over the central stable cone with both partons = C. The various choices are NLO, Gaussian smearing (s = 0.1), Gaussian smearing (s = 0.25), D0 ET profile, D0 ET profile with 2LR merging boundary (fmerge = 0.5) indicated, Gaussian smearing (s = 0.1) with ratcheting, Gaussian smearing (s = 0.25) with ratcheting, D0 ET profile with ratcheting, D0 ET profile with ratcheting with 2LR merging boundary (fmerge = 0.75) indicated. Here are some notes (in PDF format) that try to explain these figures.
EKS QCD jet codes
ET weighted flow vector in two shower event
ET distribution per 0.1x0.1 cell in two shower event
Now to look at some events generated with Pythia to correspond to jets with nominal ET's of 20, 80 and 160 Gev. In each case there is a plot of the ET weighted flow vector and a bar chart of the ET in cones of R=0.7 as a function of the eta and phi of the cone center (so you can see the jets) and also a bar chart of the ET in each tower.
Now let's look at contour plots for Event 1 at 160 GeV showing the regions where the magnitude of the ET weighted flow vector is less than 0.1 (and < 0.05) plus where the ET in towers is greater than 1.0 GeV and where the ET in cones of R=0.7 is greater than 80 GeV .
Simlarly for Event 1 at 20 GeV showing the regions where the magnitude of the ET weighted flow vector is less than 0.1 (and < 0.05) plus where the ET in towers is greater than 1.0 GeV and where the ET in cones of R=0.7 is greater than 15 GeV .
Here is another way to look at these Pythias generated jet events. These plots use color to indicate the level of activity in each tower. The double graphs compare the magnitude of the flow vector (jets show up as "atolls") with the ET in the towers or the ET in cones of R = 0.7. In either case jets are clearly identified by the overlap of small magnitude flow vectors, ringed by large magnitude, with high ET towers or cones.
160 GeV - Event 5 (2 jets + "mini"jet or shoulder, or maybe 3 jets, plus a "mini" jet): towers and cones. Looking at this event with the "seedless" jet algorithm produces 3 jets with sizeable ET, 2 of which overlap slightly. The participating towers are indicated in the corresponding flow vector plot and combined flow vector and tower ET plot.
Here are some observations on the application of various related versions of the seedless algorithm to the 160 GeV - Event 5 data in postscript form.