eflowRec is an energy flow (the technique is also known as Particle Flow in other experimenets e.g. CMS) package for ATLAS combining calorimeter, tracking and particle ID information in order to improve energy resolution for jets and taus, as well as reconstructing tau substructure. The package makes use of information from upstream reconstruction packages including CaloRec and tracking algorithms (xKalman, Moore etc.). The code has been written within the athena offline framework in C++ and uses a python frontend to configure at run-time. Instructions to use eflowRec are here.

An additional software package, PANTau, has been developed by ATLAS physicists at the University of Bonn. This software takes as starting point the output of eflowRec to undertake tau reconstruction using the eflowRec energy flow view of the ATLAS detector.

An ATLAS note detailing the algorithm and its performance, using Athena 15.6.9.8, in tau and QCD di-jet scenarios is now available. Previously we presented the performance in Athena version 12.0.6 here and as part of the ATLAS CSC excercise

Recently the PANTau software was integrated into the official ATLAS Tau Software and is under evaluation - currently we are evaluating the performance using 2011 collision-data and Monte Carlo in conjunction with the ATLAS Tau Working Group.

There are four software packages relevant to the eflowRec work. eflowRec contains all the main C++ algorithms for energy flow and the python modules to configure them at runtime, eflowEvent contains the C++ classes defining the eflowObjects which are the output of eflowRec and two packages, eflowEventTPCnv and eflowAthenaPool, deal with the conversion beteen transient and persistent eflowObjects.

Relevant talks on eflowRec, and related work on PANTau, are given in the list below:

2012

• PanTau Status (P. Bechtle (Bonn), K. Desch (Bonn), C. Limbach (Bonn), S. Matberg (Bonn), M. Hodgkinson (Sheffield), R. Prabhu (UCL), S. Fleischmann (Wuppertal), ATLAS Tau Workshop, Oxford, March 2012)

2011

• Update on eflow resource usage for taus (Mark Hodgkinson, ATLAS Event Data Model Meeting May 2011)

• PANTau and eflowRec (Mark Hodgkinson, ATLAS Reconstruction Software Meeting May 2011)

• eflow in tauRec (Mark Hodgkinson, ATLAS Event Data Model Meeting April 2011)

• Computing performance studies for eflowRec (Mark Hodgkinson, ATLAS Tau Working Group Meeting March 2011)

2010

• Energy Flow Jets Revisited with 15.6.9.8 (Mark Hodgkinson, ATLAS JetETMiss Performance Meeting October 2010)

• The progress/status on PanTau (Sebastian Fleischmann, University of Bonn, ATLAS Tau Workshop October 2010, Freiburg University)

• Energy Flow and Taus (Mark Hodgkinson, ATLAS Tau Workshop October 2010, Freiburg University)

2009

• Energy Flow using topoclusters and Local Hadron Calibration (Mark Hodgkinson, Atlas Hadronic Calibration Workshop June 2009)

2008

• Tau identification with EFLOW objects (Robindra Prabhu (University of Bonn), Atlas Deutschland Tau Meeting November 2008)

• Energy flow methods in low pt QCD di-jets using release 14.2.20.3 (Mark Hodgkinson - Atlas Jet/EtMiss Meeting November 2008)

• Energy Flow Studies in Tau Reconstruction (Sebastien Flesishman (University of Bonn), ATLAS Workshop on Tau Reconstruction, May 2008)

2007

• Energy Flow and Jet Calibration (Artemis Meeting, Chalkidiki, Greece, September 2007)

• Energy Flow for Jets June 2007 - Mark Hodgkinson

• Progress with Energy Flow for Jets March 2007 - Mark Hodgkinson

2006

• Usage of Tracking in Jet Measurements (ATLAS Calorimeter Calibration Workshop September 2006 - includes energy flow performance in 12.0.1 using postRome QCD samples - M.Hodgkinson)

2005

• Energy Flow Algorithms in eflowRec (Software Week December 2005 - R.Duxfield)

• Jets From Energy Flow at Software Week (September 2005 - M.Hodgkinson)

• Jet Reconstruction using EFlow Objects in Jets/Etmiss meeting (May 2005 - M.Hodgkinson)

• EflowRec Status Report in Jets/Etmiss meeting (March 2005 - M.Hodgkinson)

2004

• Design and Requirements Capture Document (December 2004 - M.Hodgkinson and D.Tovey)

2002

• Status Report at Software Week (November 2002 - D.Tovey)

• Status Report at Jets/Etmiss meeting (July 2002 - D.Tovey)

2001

• Status Report at Jets/Etmiss meeting (December 2001 - D.Tovey)