LHEReader

Website Journal DOI DOI arXiv

Citation: A. Desai, LHEReader: simplified conversion from Les Houches event files to ROOT format, Phys. Scripta 101 (2026) 231501, DOI: 10.1088/1402-4896/ae7772, arXiv:2603.01489.

A python script to read Les Houches Event (LHE) files and use PyROOT to convert it into a ROOT Tree

The structure of the LHE file is:

Event Level Info: Number of Particles, Status, event weight, scales, alpha_QED, alpha_QCD

Particle Level Info: PDG id, status, mother1, mother2, color1, color2, px, py, pz, energy, mass, lifetime, spin

Installation

git clone https://github.com/amanmdesai/LHEReader.git

Usage

python LHEReader.py --input input.lhe --output output.root


usage: LHEReader [-h] [--input INPUT] [--output OUTPUT]

Converts LHE files to ROOT Trees

options:
  -h, --help       show this help message and exit
  --input INPUT    Input file path and Name (can be .lhe or .lhe.gz)
  --output OUTPUT  Output file path and Name (.root file)

where input and output refer to the path of the input and output files respectively

EventLoop (Example)

The EventLoop/ directory contains an example ROOT C++ macro (EventLoop.cpp) demonstrating how to read the ROOT TTree produced by LHEReader.py and apply event selection to produce histograms and plots.

root -l -q EventLoop.cpp

Citation

@article{Desai:2026lst, author = “Desai, Aman”, title = “{LHEREADER: simplified conversion from Les Houches event files to ROOT format}”, eprint = “2603.01489”, archivePrefix = “arXiv”, primaryClass = “hep-ph”, doi = “10.1088/1402-4896/ae7772”, journal = “Phys. Scripta”, volume = “101”, number = “23”, pages = “231501”, year = “2026” } References:

  1. http://arxiv.org/abs/hep-ph/0609017