📢New paper (finally...) out today📢 'EPiC-GAN: Equivariant Point Cloud Generation for Particle Jets' with Erik (#UniHamburg too) and Jesse (#IAIFI)

A short summary below, full paper at https://arxiv.org/abs/2301.08128

One useful way to represent data from particle physics collisions is a point cloud: each collision event is a cloud of points & each point has a position in space (the position of the specific sensor or particle) and some additional features attached (for example the energy)

EPiC-GAN: Equivariant Point Cloud Generation for Particle Jets

With the vast data-collecting capabilities of current and future high-energy collider experiments, there is an increasing demand for computationally efficient simulations. Generative machine learning models enable fast event generation, yet so far these approaches are largely constrained to fixed data structures and rigid detector geometries. In this paper, we introduce EPiC-GAN - equivariant point cloud generative adversarial network - which can produce point clouds of variable multiplicity. This flexible framework is based on deep sets and is well suited for simulating sprays of particles called jets. The generator and discriminator utilize multiple EPiC layers with an interpretable global latent vector. Crucially, the EPiC layers do not rely on pairwise information sharing between particles, which leads to a significant speed-up over graph- and transformer-based approaches with more complex relation diagrams. We demonstrate that EPiC-GAN scales well to large particle multiplicities and achieves high generation fidelity on benchmark jet generation tasks.

arXiv.org

2/ An important property of point clouds is permutation invariance -- the order of the points does not matter, all that counts is their overall distribution

Solutions for neural networks (NN) on point clouds exist: DeepSets (arXiv: 1703.06114) and applied to particles (1810.05165).

The underlying idea is 'simple': apply one function (a NN) to each particle; sum the outputs; and feed that into a second NN.

3/ Our approach is similar: the #equivariant #PointCloud layer (aka EPiC layer 😎) does exactly that; but with the extra twist that we also have global attributes that exchange information with the points. This turned out to be crucial!

These EPiC layers can then be combined into a standard #GAN architecture (in fact we use LSGAN, 1611.04076) and trained the usual way

4/ We test EPiC on the super useful JetNet30 dataset from 2106.11535. (30 denotes here the number of particles in the cloud). Apart from some small artefacts, these distributions look pretty good!

The main advantage however is #speed As the structure is very simple, it is much faster than traditional simulation; but also than approaches that use more complete #graphs to represent particles (e.g. MP-GAN 2106.11535). It also scales well to higher particle numbers!

5/ As no particle-physics specific assumptions go into the architecture it might also be useful for other applications of point cloud #generation

If you want to try it out -- the #code is at https://github.com/uhh-pd-ml/EPiC-GAN

GitHub - uhh-pd-ml/EPiC-GAN

Contribute to uhh-pd-ml/EPiC-GAN development by creating an account on GitHub.

GitHub