Contents

Missing E_T

Missing \(E_T\)

The missing energy is the last of the calibrated collections we will discuss. And, from a technical point of view, different from the other calibrated objects we’ve discussed in several respects:

  • It depends on pretty much all other objects in the event. So if you apply a correction to another object, you are forced to recalculate the Missing \(E_T\).

  • It is stored as a collection of Missing \(E_T\) objects. There are a number of different Missing \(E_T\) types in a typical DAOD_PHYS file. As this was written, one could fine MET_Truth, MET_Track, MET_Core_AntiKt4EMTopo, and MET_Core_AntiKt4EMPFlow.

  • That missing \(E_T\) stored in the event is not usable. It is called the Core missing \(E_T\). An algorithm must be run to reconstruct the real event missing \(E_T\) in order to make this work.

Thus, the ServiceX backend must build the missing \(E_T\) tools to build a proper missing \(E_T\) before use.

import matplotlib.pyplot as plt
from config import ds_zee as ds

To grab the corrected missing \(E_T\) value we use the .First() func_adl predicate as below.

events = (ds
          .Select(lambda e: e.MissingET().First().met()/1000.0)
          .AsAwkwardArray('met')
          .value())

plt.hist(events.met, bins=100, range=(0, 100))
plt.xlabel('Missing $E_T$ [GeV]')
plt.ylabel('Number of events')
plt.yscale('log')
_ = plt.title(r'Truth Missing $E_T$ distribution for $Z\rightarrow ee$ events')
../_images/met_4_0.png

Rebuilding MET

Only the default Missing \(E_T\) is currently supported (built using the proper core for the jet collection you’ve used, and jets, electrons, and muons as input to the algorithm). Different missing \(E_T\) calculations are not yet simply supported. Please see this github issue for a discussion. It basically comes down to - what is a sensible way to do this without making it too “magic”. Before designing an API a number of use cases need to be collected.

The Datamodel

The data model when this documentation was last built was:

from func_adl_servicex_xaodr21.xAOD.missinget_v1 import MissingET_v1
help(MissingET_v1)

Help on class MissingET_v1 in module func_adl_servicex_xaodr21.xAOD.missinget_v1:

class MissingET_v1(builtins.object)
 |  A class
 |  
 |  Methods defined here:
 |  
 |  clearDecorations(self) -> 'bool'
 |      A method
 |  
 |  hasNonConstStore(self) -> 'bool'
 |      A method
 |  
 |  hasStore(self) -> 'bool'
 |      A method
 |  
 |  index(self) -> 'int'
 |      A method
 |  
 |  met(self) -> 'float'
 |      A method
 |  
 |  mpx(self) -> 'float'
 |      A method
 |  
 |  mpy(self) -> 'float'
 |      A method
 |  
 |  name(self) -> 'func_adl_servicex_xaodr21.str.str'
 |      A method
 |  
 |  nameHash(self) -> 'int'
 |      A method
 |  
 |  phi(self) -> 'float'
 |      A method
 |  
 |  sumet(self) -> 'float'
 |      A method
 |  
 |  usingPrivateStore(self) -> 'bool'
 |      A method
 |  
 |  usingStandaloneStore(self) -> 'bool'
 |      A method
 |  
 |  ----------------------------------------------------------------------
 |  Readonly properties defined here:
 |  
 |  auxdataConst
 |      A method
 |  
 |  isAvailable
 |      A method
 |  
 |  ----------------------------------------------------------------------
 |  Data descriptors defined here:
 |  
 |  __dict__
 |      dictionary for instance variables (if defined)
 |  
 |  __weakref__
 |      list of weak references to the object (if defined)

Further Information

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