L1ExtraFromMCTruthProd
Complete:
Introduction
Beginning in 17X, this package is no longer maintained.
This EDProducer (
L1Trigger/L1ExtraFromMCTruthProd
) generates
L1Extra
objects and a
L1CMS.GlobalTriggerReadoutRecord
based on MC particles at generator level, bypassing all the detector simulation and trigger emulation. It is intended to be a temporary tool for seeding HLT algorithms. Detector acceptance and resolution are very crudely simulated. The L1 triggers being emulated are those that were used for the PTDR vol. 2.
Description of Algorithm
The default parameters and the modules necessary for running this EDProducer are given in the file
L1Trigger/L1ExtraFromMCTruthProd/data/l1extra-from-mctruth.cff
, which includes
l1extramctruth.cfi
.
Resolution and acceptance
The trigger resolution is modeled by independent Gaussian smearing of
f,
h, and E for each particle. Although E
T, not E, is the relevant trigger variable, we do not smear this quantity directly because it is correlated with
h. The smearing widths are separately specified by parameter for each particle type (e/
g, jet,
m), and these widths are fixed, independent of
h and E
T. The default widths are the same for all particles:
sf = 0.1,
sh = 0.1,
sE = 5 GeV.
Detector acceptance is modeled as a simple
h cut, also specified by parameter separately for the calorimeter (i.e. e/
g and jets, default = 5.0) and the muon chambers (default = 2.5). The cut is applied to the smeared
h values. For jets, the boundary between the central and forward regions is defined by parameter, and the default value is 1.5.
Jet finding
Jet finding for generated particles uses the same algorithms and EDProducers as for reconstructed particles; one simply inputs
Candidate
list made by
HepMCCandidateProducer
instead of reconstructed
Candidate
objects. The particular choice of jet finding algorithm is controlled by parameter (default = midPointCone5GenJets).
In the above .cff file, we do not allow
Candidate
objects (and, thus, jets) to be made from electrons, muons, neutrinos, K
0Ls, and neutrons.
t jets in the central region are identified by matching the unsmeared jet direction to the generated
t direction, with
Df and
Dh tolerances specified by parameter (default = 0.35 for both).
The remaining jets are sorted by
h into forward or central regions. Central, forward, and
t jets are ranked by E
T, and only the top 4 candidates of each type (maximum 12 total) are retained and inserted into the event.
t jets are inserted as different collection from forward and central jets, and the two collections are distinguished by instance label ("Tau" and "ForCen", respectively).
e/g and m
Electron, photon, and muon candidates are taken from the list of stable generated particles.
Electrons and photons within the calorimeter acceptance are sorted into isolated and non-isolated e/
g candidate lists. Isolation is determined by the presence of nearby calorimeter energy deposits, and these are assumed to come from other e/
g or jet objects. The
f and
h isolation windows are adjustable by parameter (default = +-0.35 for both). In evaluating
Df, possible wraparound by 2
p is accounted for. e/
g candidates in each of the two categories (isolated and non-isolated) are ranked by E
T, and only the top 4 candidates in each category (maximum 8 total) are retained and inserted into the event.
Muons within their
h acceptance are ranked by E
T, and only the top 4 candidates in the entire detector are retained and inserted into the event. All muons have their MIP bits set, and their isolation is determined as above for e/
g, except
f and
h windows (default = +- 0.35 for both) can, in principle, be different from e/
g isolation.
MET calculation
Unlike with jets, we do not obtain the MET vector from
METProducer
using generated 4-momenta as input. Rather, the MET calculation is performed inside
L1ExtraFromMCTruthProd
in order to make use of the smeared particle 4-momenta and to exclude particles outside the
h acceptance. Because the L1 MET uses only calorimeter information, we do not include muons in the calculation. We sum transverse momentum vectors for all observed e/
g and jet objects, not just the top 4 of each category.
Total E
T is determined from the same particles as for MET. Hadronic E
T is not straightforward to calculate from the generated particles, so it is set equal to the total E
T.
L1 trigger conditions
The above particle lists are meant to approximate the outputs of the GCT and GMT, which are input to the GT. For GT emulation, we evaluate the entries in the trigger menu (listed on the instructions pages below), and we construct a
L1ParticleMapCollection
with one
L1ParticleMap
for each trigger menu entry. For each entry, the index or position in the collection corresponds to the trigger type, as specified by the enum
L1ParticleMap::L1TriggerType
. The E
T threshold(s) or prescale of each trigger is adjustable by parameter, and the default values are those used in the PTDR vol. 2 (Table E.11). For H
T, we use the total E
T described above.
The global L1 decision is constructed by OR'ing all the trigger decisions. It is recorded in the
L1CMS.GlobalTriggerReadoutRecord
, which is inserted into the event.
Instructions for use
For
CMSSW_0_9_0_pre2
through
CMSSW_1_0_0
, see
here
For
CMSSW_1_1_0_pre1
through
CMSSW_1_2_1
, see
here
For
CMSSW_1_2_2
onward, see
here
The trigger tables implemented are identical to those for
L1ExtraParticleMapProd
. View the release-by-release tables
here.
Review Status
Responsible: Main.wsun
Last reviewed by: