lAger3.6.1-1.0

Overview

First official release of the ePIC J/ψ → μ⁺μ⁻ Dataset and Analysis Tools. This repository provides
complete Monte Carlo event generation configurations and ROOT-based analysis macros for studying Deeply
Virtual Meson Production (DVMP) of J/ψ particles decaying to muon pairs in the ePIC detector at the
Electron-Ion Collider (EIC).

Event Generation Configurations

Supported Beam Configurations

• 10×130 GeV electron-proton collisions (ip6_hiacc_100x10)
• 10×250 GeV electron-proton collisions (ip6_hiacc_275x10)
• 18×275 GeV electron-proton collisions (ip6_hiacc_275x18)

lAger Configuration Files

Each beam configuration includes JSON files for lAger v3.6.1 event generation:

• lAger/10x130ep_00mrad/jpsi-10on130.disp-jpsi-00-muon.json
• lAger/10x250ep_00mrad/jpsi-10on250.disp-jpsi-00-muon.json
• lAger/18x275ep_00mrad/jpsi-18on275.disp-jpsi-00-muon.json

Complete workflow includes lAger generation, afterburner processing (abconv), and conversion to HepMC3
ROOT format for simulation campaigns.

Analysis Tools

Primary Analysis Macros

• DVMP_JPsi_Analysis.C - Main analysis script for J/ψ reconstruction from muon pairs with kinematic
  cuts:
  • Requires 3 tracks with sum charge = -1
  • Beam proton identification
  • Electron candidate identification
  • Muon pair candidate selection
  • Missing mass ≈ 0 constraint
  • Muon scattering angle ≈ 180° constraint
  • Invariant mass ≈ J/ψ mass constraint
• DVMP_histograms.C - Produces DVMP kinematic plots conforming to ePIC style guide including:
  • Efficiency and purity plots
  • Standard DVMP observables
• trackAnalysis.C - Track-level analysis and beam proton identification methods, optimized for
  high-luminosity data processing
• backgroundAnalysis.C - Background characterization and studies

Particle Identification Modules

• MuonFinder.C - Muon candidate identification with optimized selection cuts (includes LFHCAL branch)
• ElectronFinder.C - Scattered electron identification
• ParentFinder.C - Parent particle reconstruction utilities

Muon ID Studies (muonID/)

Scripts for investigating optimal muon identification strategies:

• likelihoodEHcal.C - Likelihood-based muon ID using calorimeter information
• calPlots.C - Calorimeter response analysis
• epPlots.C - Electron-proton correlation studies
• particleSearch.C - Particle identification utilities

Plotting Utilities

• ePICStyle.C/h - Official ePIC plotting style implementation

Key Features

✓ Complete event generation workflow from lAger to HepMC3 ROOT files✓ Multi-configuration support
(10×130, 10×250, 18×275 GeV)✓ Full J/ψ → μ⁺μ⁻ reconstruction chain✓ Advanced muon identification
optimization tools✓ ePIC style-compliant plotting✓ Efficiency and purity measurements✓ Background
analysis capabilities

Requirements

• lAger v3.6.1
• ROOT (with HepMC3 support)
• Afterburner (abconv) with ip6_hiacc configurations
• hepmc3ascii2root converter

Documentation

Complete instructions for event generation, processing, and analysis are provided in README.md.

Contributors

• smithalex0024 (Alex Smith)

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Full Changelog: Initial release including all event generation configurations and analysis tools for
ePIC J/ψ → μ⁺μ⁻ DVMP studies.