Particle Physics Guide

Particle Physics Guide

A skill for analyzing particle physics data, covering event reconstruction, histogram analysis, statistical methods for discovery, and the standard tools used in high-energy physics (HEP) research. Includes ROOT, uproot, pyhf, and HEPData workflows.

Data Formats and Access

HEP Data Ecosystem

Reading ROOT Files with uproot

import uproot
import awkward as ak
import numpy as np

def load_nanoaod(filepath: str, tree_name: str = "Events",
                  branches: list[str] = None) -> ak.Array:
    """
    Load a NanoAOD ROOT file into an awkward array.
    branches: list of branch names to load (None = all)
    """
    with uproot.open(filepath) as f:
        tree = f[tree_name]
        if branches is None:
            branches = tree.keys()
        events = tree.arrays(branches, library="ak")

    print(f"Loaded {len(events)} events")
    print(f"Branches: {events.fields}")
    return events

# Example: Load muon data