Alexi MestvirishviliUniversity of Iowa

DepartmentPhysics and Astronomy

Comments and question direct to Alexi.Mestvirishvili@cern.ch

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.