Upload
rae
View
40
Download
0
Embed Size (px)
DESCRIPTION
Status of the qq qq h study. Alexi Mestvirishvili University of Iowa Department Physics and Astronomy. Comments and question direct to [email protected]. Events generation by PYTHIA 6.1.52 Detector response simulation by CMSJET. f i f j f i f j h - PowerPoint PPT Presentation
Citation preview
Alexi MestvirishviliUniversity of Iowa
DepartmentPhysics and Astronomy
Comments and question direct to [email protected]
Status of the qq qq h study
Events generation by PYTHIA 6.1.52Events generation by PYTHIA 6.1.52
Detector response simulation by CMSJETDetector response simulation by CMSJET
1) fi fj fi fj h
(Higgs production via WW fusion) Higgs mass was chosen to be 300 GeV
Higgs decay h ZZ Z decay Z(1) e+e- Z (2)
Two forward jets are generated after the quarks from incoming protons radiates W ‘s
Signal eventsSignal events
2)2) WWWW ZZ ZZ 3) ZZ3) ZZ Z(1) e+e- Z (2)
4) Z+jetZ+jet
ffii f fi i ZZ00
f g f g ff Z Z00
ZZ e e++ee- -
N number of events in each set 100000N number of events in each set 100000
Background processes considered so farBackground processes considered so far
Cross-sections and luminositiesCross-sections and luminosities( ( given by PYTHIA) given by PYTHIA)
Process Cross-section (fb)
Int. Luminosity
(fb-1)
qqh 1.436 69637.9
WW ZZ 2.32x10-2 43103.5x102
ZZ 48.5 2061.9
Z + jets 4055 x 103 24.7x10-3
Tab.1Tab.1
1) All reconstructed jets must be well within CMS aperture -5 < < 5 2) Forward jets selection 2.5 < || < 53) Jet transverse energy
Et > 20GeV
4) At least one tagged forward jet satisfying the criteria above
Jets selectionJets selection
1) Presence of two isolated lepton required (one electron, one positron)
2) ||(lepton) < 2.4 3) Et (lepton) > 20GeV
4) Invariant mass of two leptons must be in vicinity of Z mass --- |M(e+e-) – M(Z) | < 5GeV
leptonsleptons (e(e++ee-- ) ) selectionselection
Jets multiplicityJets multiplicity
NOT NORMALIZ
ED
Two jet events are dominant in the signal sample
N of jets
N of jetsN of jets
N of jets
Forward jet multiplicityForward jet multiplicity
NOT NORMALIZ
ED
Most of the events has one forwardjet in all samples
N of jets
N of jetsN of jets
N of jets
Missing transverse energyMissing transverse energy E miss distributiondistribution
t
NOT NORMALIZ
ED
Z + jet events are almost completely
killed by the E miss
cut
Emiss >50GeV
was required
t
t
Emiss (GeV)t
EfficiencyEfficiency
0%10-3%Z+jets
0.016%1.04%ZZ
4.5%20.05%WW ZZ
6.1%28.63%qqh
two forward tag jets each
in opposite hemispheresat least 1 forward tag jet
Tab.2Tab.2
Number of eventsNumber of events
Nev = · · L(lhc · year)
where – efficiency for particular process L(lhc · year) – one year LHC running integrated luminosity
– particular process cross-section
Number of eventsNumber of events
02433Z+jets
0.530ZZ
0.060.28WWZZ
625qqh
2 forward tag jets each in opposite hemispheres
at least 1 forward tag jet
04048Z+jets
0.851ZZ
0.10.46WWZZ
941qqh
2 forward tag jets each
in opposite hemispheresat least 1 forward tag jet
Assuming one year running at low
luminosity L = 60fb-1
Assuming one year running at high
luminosity L = 100fb-1
t t Z Each t decays to W b with consecutive W decay to e. Z decays to e+e-.
two neutrinos from W generates large missing transverse energy. Charged leptons:
A) two e from W are out of tracker acceptance, two e from Z are in
B) one electron/positron from Z and one positron/electron from one of the W are in the tracker acceptance others out
Jets:
C) both b jets from t decay are forward i.e. could not be tagged as a b jets.
D) one b central, another forward and one forward jet is generated by ISR or FSR.
E) both b jets central, two forward jets are generated by ISR or FSR
Bkg sources to be considered in near futureBkg sources to be considered in near future
Bkg sources to be considered in near futureBkg sources to be considered in near future
A) + C) — worst case scenario, final state configuration exactly as in signal events. Significantly will affect the signal to background ratio.
A) + D) and A) + E) — b jet tagging will suppress this kind of configuration, but assuming b tagging efficiency is expected to be 60%-
70% will contribute to the signal to background ratio.
B) + C), B) + D) — in addition to the b jet tagging needs to investigate or dilepton mass distribution, in order to determine the B) + E) distribution exact shape to use side band subtraction method.
Bkg sources to be considered in near futureBkg sources to be considered in near future
t t Each t decays to W b with consecutive W decay to e. two neutrinos from W generates large missing transverse energy.
Charged leptons stays central and they are detectable.Jets:A) both b jets from t decay are forward i.e. could not be tagged as a b jetsB) one b central, another forward and one forward jet is generated by ISR or
FSR.C) both b jets central, two forward jets are generated by ISR or FSR
Needs to investigate dilepton mass distribution, in order to determine the distribution exact shape to use side band
subtraction method.