The ALICE EMCal Physics Performance Report - Status - Rene Bellwied (Wayne State University) EMCal Collaboration Meeting, Nantes, July 16 th, 2008

Purpose of the document  Originally requested by the Department of Energy and to be completed by Dec.31 st, 2008, in order to formulate the physics scope of the U.S. contribution to ALICE.  Based on discussions with ALICE the EMCal PPR will become an official addendum to the existing ALICE PPR.  It will also serve as a reference for the upcoming EMCal Technical Design Report

Organization  Report coordinator: Rene Bellwied (Wayne State)  Six prioritized sub groups with group coordinators 1.) jet reconstruction (Joern Putschke) 2.) EMCal triggering (Mateusz Ploskon) 3.) photons and gamma jets (Gustavo Conesa Balbastre) 4.) electron and heavy quark tagging (Mark Heinz / Jennifer Klay) 5.) particle identified jet measurements (Rene Bellwied) 6.) jet correlations (Claude Pruneau)  Initially groups 1 and 6 will be merged until the jet reconstruction algorithm is optimized.  Bi-weekly EVO meetings.  Several face-to-face meetings planned around ALICE weeks, ALICE-US collaboration meetings, EMCal meetings  Temporary web-page:  Report to PWG-3, PWG-4 and ALICE Physics Board regularly (either the group coordinators or the report coordinator)

Working groups  Presently 37 members, almost evenly distributed over the groups, with priority to the first four groups.  Contributors from 14 institutions: Yale, LBNL, Nantes, Wayne State, Grenoble, CERN, Jyvaskyla, ORNL, Tennessee, Creighton, Purdue, UT Austin, LLNL, Frascati Yale, LBNL, Nantes, Wayne State, Grenoble, CERN, Jyvaskyla, ORNL, Tennessee, Creighton, Purdue, UT Austin, LLNL, Frascati

General strategy  For jet reconstruction, triggering, photon, and electron (heavy flavor jet) physics improve on the existing simulations as shown in the CD-2 final physics report.  For particle identified jet measurements and jet correlations develop a performance report and interface with multiple other detector components in ALICE (TPC,TRD, ITS, PHOS). Use EMCal as tag on same side and measure fragmentation on the away-side

Main goals for group 1: jet reconstruction  Attempt to extend the reliability of jet finding algorithm to jet energies below 100 GeV. Important for single jets, crucial for jet correlations.  Optimize jet finding algorithm through comparison (kTJet, JetAn, FastJet)  Optimize quenching simulations, estimate effects elliptic and radial flow, hadron corrections, electron conversions, jet- energy correction see Peter Jacob’s talk

Main goals for group 2: jet triggering  Attempt to extend the trigger efficiency for jet energies of GeV. Check effect of jet quenching  Optimize LVL-1 algorithm by taking altering patch size/geometry based on new mapping manipulations (elelctronics).  Optimize HLT through implementation of EMCal software and subsequent merging with TPC, TRD and ITS information.

Main goals for group 3: direct photons and gamma-jets  Optimize  /  0 discrimination for direct photon and  -jet measurement (shower shape, isolation cut studies)   -jet tagging in PHOS and EMCal down to E  =20-30 GeV in order to extract reliable FF on away side. see Gustavo’s talk Isolation cut study, PbPb quenched

Main goals for group 4: heavy quark tagging with electrons  Show electron to heavy meson correspondence in AA collisions. Optimize e/h discrimination  Simulate signed DCA method for B-mesons  Physics: e, B (J/  +K or e+D) spectra, R AA, B-jets see Mark Heinz’s talk

Main goals for group 5: particle identified jet measurements  Correlate high momentum PID measurements (rdE/dx and V0 method) to triggered jet rates for single hadron or resonance and di- hadron correlation measurements in jets and between di-jets.  Determine fragmentation fnunctions for rare hadrons and particle ratios (baryon/meson or particle/antiparticle) in jets in EMCal enhanced data samples and compare to quenching model predictions.

Main goals for group 6: jet correlations  Simulate possibility of acoplanarity and jet shape measurements based on jet reconstruction resolution.  Compare jet axis correlations to leading particle correlations. di-jet angle di-jet energy correlation di-jet energy balance

Example for Groups 3/5/6: physics on the EMCal triggered away-side  High momentum resonances in jets to determine chirality (C. Markert, RB, I. Vitev, arXiv: )  Determine enhancement factors due to jet trigger and analysis improvements due to jet reconstruction Formation time of high p T resonances Measure modified resonance in away-side jet

Next steps   Collect work plans coming in (see next slides)   Collect simulation requests coming in (see next slides)   Obtain more physics-based Jet MC e.g. JEWEL

Example: work plan group 3 (Gustavo) TaskSub TaskWho PIDRe-evaluate PID parameters with last AliRoot version SUBATECH, 1 person Re-study the g/p 0 discriminationSUBATECH, 1 person EMCAL (gamma) - Central barrel (conversion) combination for Inv, Mass of p0 (not for PPR?) 1 person Direct photons Isolation cut Re-evaluate IC with larger amount of events, specially jet-jet, PYTHIA Gustavo Compare predictions for different generators and theory 1 person Decay photon subtraction with Invariant Mass1 person Gamma-jetImprove HI background rejection1 person Estimate effect of jet-jet contamination1 person Code implementation in Analysis FrameGustavo

Example: work plan group 4 (Jennifer) TaskTools Manpower Statistics Revisit rates (higher stats) PYTHIA + Material -- -kinematics info 0.5 person100k x 15 jet p T bins Re-check e-ID (track- matching, p/E) PYTHIA/HIJING + Full simulation 0.5 person Single e,  0 10k x ~10 p T ranges 100k x 15 jet p T bins + 10k HIJING bkg Electron and E-Jet trigger (rates/bkg) PYTHIA/HIJING + AliEMCALTrigger, HLT Trigger Group? 100k x 15 jet p T bins + 10k HIJING bkg Electron spectra/R AA (e  B/D corresp., compare to TPC and TPC+TRD) PYTHIA + Full simulation 1 person100k x 15 jet p T bins 100k x ~5 p Thard bins each of MSEL4 and MSEL5 D/B Spectra/R AA (e+D, J/Psi+K, mis-ID) PYTHIA + Full simulation 1-2 people100k x 15 jet p T bins 100k x ~5 p Thard bins each of MSEL4 and MSEL5 B-jets (DVM,W,JETAN reco, FF, other tag methods) PYTHIA/HIJING + Full simulation 2-3 people100k x ~5 p Thard bins each of MSEL4 and MSEL k W-boson decays 10k HIJING bkg

Example Simulation requests   Ideally with AliRoot and through the GRID   Group GeV jet energy spectrum pp and PbPb statistics for each of the bins remains to be determined 10% of planned running year statistic would be comfortable   Group 3 pp exists so mostly PbPb Gamma (EMCAL/PHOS) – jet (quenched, not quenched jet-jet (quenched/not quenched) A couple of quenching scenarios? q= 20 and q=50, models PQM, PYQUEN, maybe JEWEL?   Group 4 see work plan

Summary  A dedicated effort to define the physics scope enhancement due to the EMCal in ALICE is underway.  We hope to complete the document within six months in close collaboration with the existing PWG’s in ALICE.  Any input, comments, suggestions, help is much appreciated.