MissingETComposition Object
Adam Yurkewicz (Stony Brook)
Donatella Cavalli (Milan)
Peter Loch (Arizona)
Silvia Resconi (Milan)
Rolf Seuster (MPI)
Thanks also to Pierre-Antoine Delsart, Marcin Nowak, Scott Snyder
Motivation for a New
MissingET Data Structure
• Useful to have more MissingET information available than just
final sums (MET_RefEle, MET_RefJet, MET_CellOut, …)
– i.e. would like to easily answer the question “What muons
were used to build the MissingET muon term?”
• Improve infrastructure to properly remove overlaps between
different types of objects inside the MET algorithm
• Provide information needed to calculate MET significance
• Simplify analysis; this should usually be the one and only
object users retrieve from the AOD for MissingET information
2
MissingETComposition Structure
Object Pointer
Weight (px)
[float]
Weight (py)
[float]
Weight (pt)
[float]
Status Word
[Unsigned short]
Jet 1
Wpx_jet_1
Wpy_jet_1
Wet_jet_1
P4SignalState::
CALIBRATED
Jet 2
Wpx_jet_2
Wpy_jet_2
Wet_jet_2
P4SignalState::
CALIBRATED
Muon 1
Wpx_muon_1
Wpy_muon_1
Wet_muon_1
COMBINED
Muon 2
Wpx_muon_2
Wpy_muon_2
Wet_muon_2
SPECTROMETER
Electron 1
Wpx_ele_1
Wpy_ele_1
Wet_ele_1
EM
Cluster 1
Wpx_clus_1
Wpy_clus_1
Wet_clus_1
P4SignalState::
CALIBRATED
…
…
…
…
…
3
MissingETComposition Structure
• 3 weights per object are object’s contribution to MissingET, sumet
– Weight is product of all differences between reconstructed object’s stored
px,py,pz, and what is used by MissingET algorithm
• 16-bit status word holds flags about object calibration/state information (most
bits currently unused)
• From the MissingETComposition object, can calculate the MET terms:
///////////////////////////
const MissingETComposition *metcomp;
storeGate->retrieve(metcomp,”MET_RefComposition”);
MissingETComposition::const_iterator<Jet> fJet(metcomp->beginIterator<Jet>());
MissingETComposition::const_iterator<Jet> lJet(metcomp->endIterator<Jet>());
float my_METRefJet_x = 0.0;
for (; fJet != lJet; fJet++) {
my_METRefJet_x -= (*fJet)->px()*fJet.getParameter().wpx();
}
4
Input Electron Collection
METRefEleTool
Select electrons from
input electron container
ele_2
ele_1
ele_3
…
ele_n
Backnav to cells
Keep incremental sums
Compute weights that
objects contribute to
MET
Set status words with
calibration/state information
Register information in
METComposition object
METRefJetTool
METRef***
MET_RefEle_1
MET_RefEle
MET_RefEle_1+2
Weight_1=
-RefEle1/ele_1
Weight_2=
[RefEle_1 –RefEle_2]/ele_2
Weight n=
[RefEle_n-1 - RefEle_n]/ele_n
sw_1
sw_2
sw_n
METComposition Object
Ele_1, weight_ele_1, status_word_ele_1
Ele_2, weight_ele_2, status_word_ele_2
….
Ele_n, weight_ele_n, status_word_ele_n
Jet_1, weight_jet_1, status_word_jet_1
Jet_2, weight_jet_2, status_word_jet_2
….
Jet_n, weight_jet_n, status_word_jet_n
….
5
Current Status
• Code in svn, 15.7.0 nightly
– MissingET-03-02-00
– MissingETEvent-00-04-00
• METComposition object not written to ESD/AOD by default;
can be switched on in job options
– Muons not filled into METComposition object yet, coming
soon
• Size on disk: 3.1 kb/ev over 1000 J3 events,
– MET_CellOut ~200 clusters/event
6
Validation
Sanity check: Read back
MissingETComposition map from AOD
and calculate each MET term, compare to
standard METRef* containers
7
Jet Weights in J3 Sample
• Weights for jets with pt > 20 GeV for J3 sample
• Difference from 1 from overlap removal and fact that
numerical inversion not applied in MET algorithm
8
Example Usage
• Run 142191, event 206357, MET_RefFinal_MET = 50 GeV
• From METComposition, know 21 topo clusters contribute to
MET_CellOut term (+ have all kinematic information)
• 2 jets contribute to MET_RefJet term (+ have all jet info)
• METComposition can
be used by ATLAS
event displays to show
which objects
contribute to MET
terms (and how much)
9
Future
• Finish muon tool
• After that, it’s ready for use
– Would like to backport into 15.6.x to make
available for coming data
• Provide some user-friendly access methods
10