version: "1.0.0" name: madanalysis-analyzer description: Run MadAnalysis5 analysis on generated event files via Magnus cloud. Triggers when the user wants to analyze Monte Carlo events, create kinematic distributions, apply event selections, or produce cut-flow reports. Supports parton-level (LHE), hadron-level (HepMC), and reconstruction-level (LHCO/ROOT) analysis.

MadAnalysis Analyzer

Overview

This skill runs MadAnalysis5 in normal mode for post-generation analysis of Monte Carlo event files. It uses the madanalysis-process blueprint on the Magnus cloud platform (see magnus skill).

CRITICAL: Do NOT write `submit` in your analysis script. The cloud runner automatically appends submit analysis_output. Any user-written submit lines are stripped before execution. This differs from standalone MadAnalysis5 usage where submit is required.

Output Paths

All paths are relative to the working directory. Scripts use relative paths so they can be directly cp'd into the reproduction package.

Naming conventions:

• <label>: a short, descriptive tag for the analysis (e.g. dilepton, dilepton_mass, signal_region)

Workflow

Step 1: Locate Event Files

Find the event files from the MadGraph output directory. After madgraph-launch, events are in:

<output>/Events/run_XX/
├── unweighted_events.lhe.gz              # parton-level
├── tag_1_pythia8_events.hepmc.gz         # hadron-level (if Pythia8)
├── tag_1_delphes_events.lhco.gz          # reco-level LHCO (if Delphes)
└── tag_1_delphes_events.root             # reco-level ROOT (if Delphes)

Choose the appropriate file based on your analysis level.

Step 2: Build the Analysis Script

Write MA5 commands as a multi-line string. Use {EVENTS_DIR} as a placeholder for the events directory path — it is replaced at runtime with the actual download location on the cloud.

import {EVENTS_DIR}/Events/run_01/tag_1_delphes_events.lhco.gz as signal
set signal.type = signal
set main.lumi = 100
 
plot PT(mu[1]) 50 0 500
plot MET 50 0 500
plot M(mu+ mu-) 100 0 200
 
select N(mu) >= 2
select PT(mu[1]) > 25

CRITICAL: Do NOT write `submit` — the cloud runner automatically appends submit analysis_output to your script. Any user-written submit lines are stripped before execution.

Step 3: Run the Analysis

Execute the madanalysis-process blueprint using magnus run (see magnus skill):

magnus run madanalysis-process -- \
  --events path/to/pp_ttbar \
  --script "import {EVENTS_DIR}/Events/run_01/unweighted_events.lhe.gz as sample
set sample.type = signal
plot PT(mu+) 50 0 500
plot M(mu+ mu-) 100 0 200
select N(mu+) >= 1" \
  --output path/to/ma5_output \
  --level parton

Parameters:

The events directory is uploaded via FileSecret. On success, the analysis output is downloaded to --output.

WARNING: If --output points to an existing directory, it will be deleted and replaced by the download.

Downloaded directory structure (example: --output path/to/ma5_output):

path/to/ma5_output/
└── analysis_output/
    └── Output/
        └── HTML/
            └── MadAnalysis5job_0/
                ├── index.html
                └── selection_N/         # one per selection cut
                    └── *.png            # histogram images

Analysis Levels

Level must match the event file format:

• LHE files require --level parton
• HepMC files require --level hadron
• LHCO/ROOT files require --level reco

Event File Selection

When multiple event file types exist in a run directory, prefer higher-level formats (priority order):

1. tag_*_delphes_events.lhco.gz — reco-level, LHCO (most common for Delphes)
2. tag_*_delphes_events.root — reco-level, ROOT
3. tag_*_pythia8_events.hepmc.gz — hadron-level
4. unweighted_events.lhe.gz — parton-level (always available)

MA5 Script Quick Reference

Importing events

import {EVENTS_DIR}/Events/run_01/unweighted_events.lhe.gz as signal
import {EVENTS_DIR}/Events/run_01/tag_1_delphes_events.lhco.gz as bkg

Configuring datasets

set signal.type = signal
set bkg.type = background
set bkg.xsection = 831.76          # cross section in pb
set main.lumi = 100                # luminosity in fb^-1
set main.normalize = lumi
set main.stacking_method = stack

Plotting observables

plot PT(mu[1]) 50 0 500            # leading muon pT
plot MET 50 0 500                  # missing ET
plot M(mu+ mu-) 100 0 200         # dimuon invariant mass
plot N(j) 15 0 15                  # jet multiplicity
plot DELTAR(e-[1], j[1]) 40 0 10  # deltaR(leading electron, leading jet)

Particle ranking: mu[1] = leading (highest-pT) muon, mu[2] = sub-leading.

Applying selections

select N(mu) >= 2                  # require >= 2 muons
select PT(mu[1]) > 25              # leading muon pT > 25 GeV
reject MET < 50                    # reject events with MET < 50
select 80 < M(mu+ mu-) < 100      # mass window

Selections are applied sequentially (AND logic). Order matters for cut-flow tables.

Reference Documentation

• See references/madanalysis_reference.md for the complete MA5 command reference, including all observables, selection syntax, output format, and analysis examples