CMSDAS@IIT Hyderabad 2025: Jets and MET Short Exercise

This tutorial will provide you with the basics you need to deal with jets and missing transverse momentum or MET in your analysis. We start with the basics of a jet, how they are reconstructed, what algorithms are used, etc. Then, we give examples with scripts on how to access jets and use them in your analysis frameworks, including corrections and systematics. In the second part of the exercise, we examine jet substructure algorithms, which have many uses, including the identification of hadronic decays of heavy SM particles such as top quarks, W, Z, and H bosons, as well as mitigation of pileup and others.

For the MET exercise we will start with an introduction to its reconstruction and the fundamental concepts underlying its calculation, ensuring a solid foundation for understanding its role in physics analyses. Next, we delve into MET calibration and uncertainties, providing the tools to accurately account for and quantify potential deviations. Finally, we cover the identification of sources that can lead to artificial MET and discuss Noisy Event filters (formerly known as MET filters) designed to mitigate such effects, equipping you to confidently handle MET-related challenges in your research.

The tutorial is designed to be executed on CERN LXPLUS, following the setup step, using jupyter notebooks. On this website, you will find links to instructional slides and more information about the topics to walk you through the exercises.

For general questions, problems, debugs, or asking for help from experts on jets and MET: CMS Talk JetMET category

Follow the CMS workbook on jet analysis: WorkBookJetAnalysis

What is this set of exercises trying to do?

It gives you hands-on experience accessing jet collection in an event, plotting basic jet quantities, and applying jet energy correction.

  • This is a 101 on accessing jets and MET in the CMS framework without assuming prior knowledge.
  • Make you familiar with basic jet and MET types and algorithms and how to use them in your analysis.
  • Illustrate each exercise using real-life example scripts.
  • Give a comprehensive reference to more advanced workbook examples, additional resources, and pedagogical documentation in one place.

What are these exercises NOT meant for?

To summarize the CMS JetMET software machinery comprehensively or the jet analyses performed at CMS.

What do we expect from you?

  • You should have followed all the pre-exercises and have a cmslpc account, grid certificate, and a current web browser.
  • It would be best if you worked through the notebooks, ensuring you understand every step and every plot.
  • The exercises are prepared to be run directly from a cmslpc node, with non-interactive notebooks to follow and discuss the exercises.

Facilitators CMSDAS IIT Hyderabad 2025

Photo of the facilitators

Support

Join the SE-JetMET Mattermost channel and don’t hesitate to ask for help from the facilitators in the room.

Prerequisites

CMS DAS Pre-exercises

Schedule

Setup Download files required for the lesson
00:00 1. Jets 101 What is a jet?
Are there different types of jets? What is a recluster algorithm?
Which types of jets do we use in CMS?
01:00 2. Pileup Reweighting and Pileup Mitigation What is pileup and how does it afffect to jets?
What is the basic jet quality criteria?
02:00 3. Jet energy corrections and resolution What are jet energy correction?
What is jet energy resolution?
03:00 4. Jet Substructure What is jet substructure?
How to distinguished jets originating from W or top quarks?
04:00 5. Missing Transverse Energy 101 What is MET? How is MET reconstructed?
What are the types of MET at CMS?
Examples of analyses with MET at CMS
04:30 6. MET Calibrations Why do we need to calibrate MET? How is the performance measured?
What are the different ways of calibrating MET at CMS?
What is MET phi modulation? How to correct for it?
How is the uncertainty on MET estimated?
05:00 7. MET performance How do we measure the MET performance (i.e. MET scale and MET resolution) ?
05:30 8. Handling Anomalous MET Events What is anomalous MET?
How to identify these events?
06:00 Finish

The actual schedule may vary slightly depending on the topics and exercises chosen by the instructor.