Jet Energy Corrections for High-Luminosity LHC

Introduction

The 2020 update of the European Strategy for Particle Physics puts the HL-LHC at the focal point, “together with continued innovation in experimental techniques”. Its primary goals include searching for new physics at high energy, exploration of the Higgs potential, and precision tests of the Standard Model.

Importance of Jet Energy Corrections

At a hadron collider such as LHC, practically all measurements rely on jet energy corrections (JEC). Many important benchmark channels, such as:

1. Top quark decaying to b jets
2. ud or cs jet pairs
3. Inclusive jets produced with numerous gluon jets

have JEC as their limiting uncertainty. At present, the JEC uncertainties are at a level of 1% overall, with similar additional uncertainties from flavor-specific JEC from simulation only.

Simulation Biases

However, evidence suggests that the simulation is biased at the level of these uncertainties, and that these biases will become the decisive factor for further progress. Here we show how to correct these biases with data-driven methods and bring the total uncertainties toward the 0.1% level.

Measurement Techniques

We found that with an integrated luminosity of more than 100/fb, the Z+flavor channel can be used to precisely measure all flavor-JEC, when combined with our novel techniques to address flavor-dependent biases from:

• Initial and final state radiation
• Underlying event
• Heavy-flavor neutrino production

Furthermore, we found that inclusive jet production can be used to monitor further drifts of JEC at 0.1% precision, and that our observations can be motivated with a parameterized model of particle flow jet response.

Conclusion

Our results plot a path to JEC at the HL-LHC high pileup environment, and show how to systematically control the leading simulation uncertainties with data, allowing many physics analyses to improve their JEC-related systematic uncertainties.

We anticipate our work will be a starting point to transition to 0.1%-level precision in JEC across the field and that it will lead to a number of precision jet physics measurements as a result.