JetCLR

Core codebase for JetCLR, a high-energy-physics tool for the self-supervised contrastive learning of jet representations.

JetCLR uses a permutation-invariant transformer-encoder network and a contrastive loss function to map jet constituents to a representation space which is approximately invariant to a set of symmetries and augmentations of the jet data, and is discriminant within the dataset it is optimised on. The symmetries and augmentations are coded in scripts/modules/jet_augs.py, they are:

• symmetries:
  • rotations in the rapidity-azimuthal plane, around the transverse-momentum-weighted centroid of the jet
  • translations in the rapidity-azimuthal plane
  • permutation invariance of the jet constituents, this is ensured by the network architecture
• augmentations:
  • smearing of constituent coordinates, inversely proportional to their transverse momentum
  • collinear splittings of jet constituents

The scheme for optimising the network is inspired by the SimCLR¹ paper, and is coded here in scripts/run_jetclr.py. The mapping to the new representation space is entirely self-supervised, using only the physically-motivated invariances to transformations and augmentations of the data. Truth labels are not used in the optimisation of the JetCLR network.

For questions/comments about the code contact: [email protected]

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This code was initially written for the paper:

Symmetries, Safety, and Self-Supervision
https://arxiv.org/abs/2108.04253
Barry M. Dillon, Gregor Kasieczka, Hans Olischlager, Tilman Plehn, Peter Sorrenson, and Lorenz Vogel

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_{1: 'A Simple Framework for Contrastive Learning of Visual Representations', Ting Chen, Simon Kornblith, Mohammad Norouzi, and Geoffrey Hinton (arxiv:2002.05709)}