[PWGCF] Add Lambda and anti-Lambda spin-correlation analysis

[Akash-Raj-285]

Summary

This draft PR introduces a PWGCF workflow for studying spin correlations in Lambda–anti-Lambda, Lambda–Lambda, and anti-Lambda–anti-Lambda pairs.

The workflow reconstructs and selects Lambda and anti-Lambda candidates, provides optional Monte Carlo truth and efficiency processing, and produces same-event and mixed-event spin-correlation distributions.

The spin observable is constructed from the proton and antiproton daughter momenta after boosting them into their respective parent hyperon rest frames.

Main components

The workflow contains the following analysis tasks:

• LambdaOrAntiLambdaProducerWithSpin

  • Reconstructs Lambda and anti-Lambda candidates from V0 candidates.
  • Applies event, daughter-track, PID, topology, and Lambda kinematic selections.
  • Stores event information, candidate kinematics, topology variables, and daughter information in derived tables.

• LambdaAntiLambdaSelector

  • Separates the combined candidate table into Lambda and anti-Lambda tables.
  • Provides the tables consumed by the pair-analysis task.

• LambdaAntiLambdaPairAnalysis

  • Constructs Lambda–anti-Lambda, Lambda–Lambda, and anti-Lambda–anti-Lambda pairs.
  • Produces same-event and mixed-event angular-correlation histograms.
  • Stores pair and event counters needed for normalization.

• LambdaAntiLambdaMcRecoTableProducer

  • Produces reconstructed candidates with Monte Carlo truth information.
  • Produces event-selection information associated with generated MC collisions.

• LambdaAntiLambdaEfficiencyPlots

  • Produces reconstructed and generated Lambda/anti-Lambda efficiency histograms.

• LambdaAntiLambdaSelectionCutFlow

  • Provides reconstructed-event and Lambda-selection cut-flow histograms.

The MC-specific processing functions use PROCESS_SWITCH and are disabled by default, allowing them to be enabled explicitly for MC processing without changing the workflow topology.

Same-event pair classification

Same-event pairs are divided into short-range and long-range samples.

A pair is classified as short range when both conditions are satisfied:

|Delta y| < 0.5
|Delta phi| < pi/3

[github-actions]

O2 linter results: ❌ 1 errors, ⚠️ 29 warnings, 🔕 0 disabled