Introduction Multi-jets final states are of major interest for the LC Physics EFlow : An essential test to design the foreseen detector Software (Algorithms) is as important as the hardware (detector) -> The two aspects are totally linked

IntroductionP. Gay2’ A study of an energy resolution of a digital calorimeter A. SokolovIHEP20’ Simulation Studies for a digital Hadron CalorimeterA. MacielNIU20’ Impact of the SET in photon measurementM. BerrgrenLPNHE10’ Reconstruction Package for a LInear ColliderJ.C BrientLLR10’ Comparisons of Fast Monte Carlo Energy flow SimulationsM. RonanLBL20’ BRAHMS reconstruction V. Morgunov Ties Benhke DESY20’ NLC Energy Flow studiesN. GrafSLAC20’ Analytic Energy flowP. GayLPC20’ Discussion about future plansAll20’ EFLOW session AGENDA

8 talks for a 2:40 session with a significant contribution from US Colleagues Various topics covered : single particle reconstruction Jets reconstruction Fast simulation

EFlow : An essential test to design the performance of the detector Then impact on Eflow of a new/alternative sub-detector has to be estimated About the SET the question has been addressed in this way 20% of the photons in processes HZ,WW, QQ have energy less than 5 GeV; if they convert SET improves their reconstruction Work is preliminary further work on Physics case with full simulation is expected

EFLOW procedure The different approaches follow mainly similar scheme (JC Brient, N Graf, V Morgunov, PG)  Track cluster association following a tube/road in vicinity of the track extrapolation  Remove in Calorimeters parts associated to charged clusters  Characterize remaining energy deposition (em and neutral hadron) What do we need Photon reconstruction and ID neutral hadron and ID test on full simulated Physics events what do we have ?

Photon Many works have been developed with different approaches Classical clustering (JCBrient) Stochastic approach/pattern recognition (PG) Likelihood+covariance matrix (N Graf) Studies performed w/ single particles but also in jet environment Next Finalize when necessary Compare the various options in term of performance Push on new preliminary ideas

Neutral hadron Great importance and large impact Neutral hadron reconstructed replaced by the Truth MC contribution

Studies and comparisons between digital and analog hadron calorimeters (A. Maciel & A. Sokolov) At least similar results on resolution are obtained by both options Improvements expected in both scheme, as an illustration, a NNet approach based on Hits multiplicities information (A. Sokolov) improves the resolution by a factor 1.4; further development foreseen Hits multiplicity and Em deposition in ECAL combined (PG) Neutral hadron Neutral hadron clustering (A. Maciel) 2D Layer/layer inspection and longitudinal stacking Cell domain search in 3D (new idea)

Complete event environment and Eflow packages Eflow packages appear with various levels of development MOKKA+REPLIC (JC Brient) already available on CALICE Coll. Web page SNARK+BRAHMS (V. Morgunov) release very soon Other stuffs foreseen for end of June (N. Graf & PG) Sum of em energiesNumber of photon in an event

Test the Eflow performances Two levels 1 Internally to the EFLOW group  We have to perform solid and conclusive comparisons between the different options understand what are the differences, the good/bad points, the discrepancies, the bugs etc …  Share the same events We will use benchmark processes : WW, ZZ, WWvv, ZZvv and 800 GeV The list is limited and this benchmark is an internal TOOL for Eflow  Share the same observables dijet energy resolution and dijet angle resolution

Second level : input for Fast Simulation outside Eflow group, People have to test the different Eflow options proposed in the context of Physics analyses as an example Fast Simulation studies (M. Ronan) Then Eflow group has to provide such an information Structure of input/output format has to be coordinated w/ Simulation group (of course) 3rd Step Feedback from Physics analysis to EFLOW group in order to improve Eflow algorithm itself or sophistication of the provided output

Even if the man-power is presently small, many ideas are debated and developed Newcomers are Welcome NEXT Future  Provide results on Physics case (benchmarks) and perform the comparisons  Provide Eflow objects information to Fast Simulation  Reinforce connection with Tracker system people  Reinfornce Collab./synergy with US/ASIA colleagues