Muon AOD:

1. ESD Standard AOD Muon - AOD Dimuon - AOD Developments of the PWG3 muon analysis code The analysis train for the muon analysis should be based on the creation of the following files: Standard AOD: • obtained filtering the ESD information Muon AOD: N  1 • replica of the standard AOD, containing only events where at least one muon is present N  2 Dimuon AOD: • replica of the standard AOD for events with N  2, adding a new branch for dimuons Alice Offline Week, October 23rd 2008

2. Standard AOD AOD tag Muon - AOD Muon AOD creation The Muon AOD is created: 1) selecting events with N  1 2) replicating the standard AOD branches Selection of muon events: It’s based on the AOD tag files AliEventTagCuts *evCuts = new AliEventTagCuts(); evCuts->SetNMuonRange(1,10); SetNMuonRange select muons according to the global PID Need to define a setter to select only muons detected in the muon spectrometer (to be implemented)

3. Replica of the AOD branches Replica of the standard AOD branches: The possibility of replicating the standard AOD branches is implemented in ANALYSIS/AliAnalysisTaskSE.cxx(.h) It is possible to choose which branches have to be replicated using some setters: STEER/AliAODHandler.cxx(.h) aodOutputHandler->SetNeedsHeaderReplication(); aodOutputHandler->SetNeedsTracksBranchReplication(); aodOutputHandler->SetNeedsVerticesBranchReplication(); aodOutputHandler->SetNeedsV0sBranchReplication(); aodOutputHandler->SetNeedsTrackletsBranchReplication(); aodOutputHandler->SetNeedsPMDClustersBranchReplication(); aodOutputHandler->SetNeedsJetsBranchReplication(); aodOutputHandler->SetNeedsFMDClustersBranchReplication(); aodOutputHandler->SetNeedsCaloClustersBranchReplication(); The replica of the AOD branches is of general use (i.e. not only for the Muon AOD creation) Names of the AOD branches are the same in the standard and in the Muon-AOD  Macros can be run on both without changes

4. MUON AOD (2) Input:AliAODs.root, AOD.tag.root Output:AliMuonAODs.root Analysis Task: PWG3/muon/AnalysisTaskFromStandardToMuonAOD.cxx We can select the information we want to replicate in the Muon-AOD (header of the event, tracks, vertices…) In principle, at this level, we should keep all the available information 6 tracks 3729 tracks 70 tracks Tracks belonging to events where there is at least one muon (Muon AOD) All Tracks (Standard AOD) Muon tracks (Muon AOD)

5. Dimuon AOD creation The Dimuon AOD should be created: • 1) selecting events with N  2, using tag cuts • replicating the interesting AOD branches • creating a dimuon object and adding it in a new Dimuon branch Analysis Task: PWG3/muon/AliAnalysisTaskFromMuonToDimuonAOD.cxx(.h) Example from a generation of upsilon events pT pT Mmm

6. 2 Standard AOD Standard AOD 1st analysis train 1st analysis train N  1 N  1 N  2 Muon AOD N  2 2nd analysis train Dimuon AOD Muon AOD Dimuon AOD Dimuon AOD creation (2) 2 possibilities can be foreseen for the Dimuon AOD creation: 1 Option 2 should be preferred but is it possible to use two different tag selections within the same analysis train?

7. AliAODDimuon The dimuon creation is based on the AliAODDimuon.cxx(.h) and AliAODEventInfo.cxx (.h) classes. The dimuon object is created from the pointers to two AliAODTracks AliAODDimuon(TObject *mu1,TObject *mu2,TObject *evinfo) AliAODEventInfo class which provides additional infos on the AliAODEvent, not included in the AOD header, namely • the beam energy (used in the calculation of the cosCS) • information on the trigger This class should eventually be removed, because the information it contains should be retrieved from the AOD • the decoding of the trigger mask should be provided to the AOD at a higher level • the beam energy is stored in the ESD/AOD tag file, but it is not written in the AOD header  not directly accessible?

8. Files dimension Some numbers on files dimension Typical ESD event (from PDC08/LHC08x pp@ 14TeV) : ~ 16 KB/event compression factor ~ 5 Standard AOD : ~ 3.1 KB/event Events with N  1 ~ 1% Fraction of events with N  2 / N  1 ~ 1% Size of the dimuon branch: ~ 0.02 KB/event negligible with respect to standard AOD event size (~3 KB) Because of the small size of the files, we should create the Muon/Dimuon AODs merging several files

9. Event mixing For the combinatorial background subtraction we should use the event mixing technique. We can use the AliMuonAOD.root as input for the mixing, since it contains single muon tracks Muons should be mixed if they belong to events with similar characteristics pools have to be defined According with the mixing framework, pools definition can be based on the tags Need to have tags matched to the Muon-AOD Need to check if the information used for the pool definition (z of the vertex, centrality, reaction plane…) are contained in the tags Output of the mixing framework should be a Mixed Dimuon-AOD containing dimuon infos and infos on the pool definition

10. Standard AOD n Standard AOD 1 Standard AOD 2 … header tracks branch vertices branch other branches header tracks branch header tracks branch vertices branch vertices branch other branches other branches Mixing events Muon AOD Muon AOD header tracks branch vertices branch … AliAnalysisTaskME Pools DiMuon AOD header tracks branch dimuon branch vertices branch … Mixed DiMuon AOD dimuon branch Pool info for normalization Schema of the analysis train for MUON analysis Merging

11. Conclusions and requirements for the Offline meeting A proposal for the creation of the Muon/Dimuon AOD within the analysis framework has been presented Muon/Dimuon AODs will have a smaller size with respect to standard AOD  a merging of the files should be foreseen The Muon-AOD will also be the input for the background estimate using the event mixing AOD tags should be created for Muon/Dimuon AODs The code to create Muon/Dimuon AOD, starting from the standard AOD, is ready and updated to recent developments of the analysis framework • we would like to test the Muon/Dimuon AOD production within the official analysis train How the production of these AOD should be included? Should it be done in the same analysis train, where the creation of the standard AOD (from ESD) is done, or in other subsequent trains?