SLAC Physics Analysis Retreat
Jet/Met sub-group

This page provides a list of selected topics to work and discuss during the SLAC physics analysis retreat, as well as basic documentation, and links to datasets. The goal is to be able to produce results in each area, by the end of the workshop.
More topics may be added after the general physics meetings on Monday, motivated by everyone's interests.

  1. Proposed topics
  2. Documentation
  3. Data Samples
  4. Example of CBNT Analysis

Proposed topics:

Jet Algorithms

Contact person: Peter Loch

Jet Calibration

Contact person: Peter Loch

Jet Energy Resolution

Contact person: Ariel Schwartzman

Event Shapes

Contact person: Peter Loch

Jets with Tracks

Jet energy resolution can be improved by the use of track information. For instance, jets with different fraction of track energy have different energy response. Thus, track-based jet energy response corrections result in additional improvements in jet resolution. A tentative list of projects is listed bellow:

Contact person: Ariel Schwartzman

Jet-Vertex Association

At high luminosity, events will contain soft jets associated to additional minimum bias interactions. It is important to develop techniques to identify (and remove) jets not produced in the hard scatter interaction.
DZero developed a Jet-Vertex association algorithm based on tracks, that associates to each jet, a probability that it originates from a particular vertex interaction.

Contact person: Ariel Schwartzman

Comparison of MET calculation using Clusters/Objects

Several studies of MET using clusters and physics objects can be made using a special version of CBNT root tuples containing topological clusters and their link to physics objects. Projects in this area include:

Contact person: Peter Loch

Unclustered Energy Resolution and Calibration

Contact person: Ariel Schwartzman

MET Significance

The MET significance algorithm computes, in an event-by-event basis, what is the probability that the observed MET arises from instrumental effects taking into account the resolution of the measured physics objects, the unclustered energy, and the topology of the event.
This idea, developed at DZero, was shown to be very effective to reject QCD background.
There are several areas to contribute to the development of this technique in ATLAS:

Contact person: Ariel Schwartzman

Jet/Met Documentation:

Data Samples:

All data samples are located in $ATLROOT/data/jetmet/

Information about the ntuple content:

Example Analysis code:

This is the list of steps to be able to analyze CBNT root tuples:

  1. Generate a skeleton class for analysis:
    root [mysample.root]
  2. Insert your analysis code in the Loop method of Analysis.C
  3. Compile

    Create the following script called run.csh

    gSystem->CompileMacro ("Analysis.C", "k");
    TTree* tree = 0;
    TFile *f = new TFile("mysample.root");
    f->cd("CBNT"); tree = (TTree*)gDirectory->Get("t3333"); 
    cout << "Number of events = " << tree->GetEntries() << endl;
    Analysis* a = new Analysis(tree);
  4. Run:
    root run.csh
    root [0] > a->Loop();