Status of the HZ Analyses

John Marshall HZ Analyses 1

Status of the HZ Analyses

LCD WG Meeting, 03/07/2012

J.S. Marshall, University of Cambridge


350GeV HZ Recoil, L=500fb-1

• Model independent recoil analysis:Z decays to charged leptons.

• Identify leptons and compute recoil mass, using knowledge of initial state.

Mean RMS

mH 119,950.4 MeV

130.4 MeV

mH 133.3 MeV

6.5 MeV

nsig 4.91 % 0.19 %

mH 119,915.4 MeV

302.5 MeV

mH 299.8 MeV

30.4 MeV

nsig 8.08 % 0.64 %

mH 120,012.0 MeV

397.2 MeV

mH 394.3 MeV

36.1 MeV

nsig 7.93 % 0.59 %

X

eeX

eeX

Brem

.

X


Comparison with ILC ResultsStarting point:No selection cuts

Selection must work harder than at ILC, but achieves similar S/B

Reco quantities,full selection

mH nsig

ILC 110 MeV 5.2 %

CLIC 226 MeV 8.3 %

• Integrated luminosity: 175 fb-1

• Comparison of results for X channel:


E’ Correction Weights• Try to understand shape differences using ILC/CLIC

E’ distributions from Frank.

• Use distributions to obtain E’ weight: CLICILC.

L = 175 fb-1 mH nsig

ILC 110 MeV 5.2 %

CLIC, Reco 226 MeV 8.3 %

CLIC, Reco , E’ weight 151 MeV 7.3 %

CLIC, True 174 MeV 7.0 %

CLIC, True , E’ weight 90 MeV 6.3 %

Starting point:No selection cuts


Final State Radiation

L = 175 fb-1 mH nsigTrue 174 MeV 7.0 %

True post FSR 210 MeV 8.1 %

Reco 226 MeV 8.3 %

True , E’ weight 90 MeV 6.3 %

True post FSR, E’ weight 112 MeV 7.0 %

Reco , E’ weight 151 MeV 7.3 %

Starting point:No selection cuts


Momentum Resolution• Attribute difference between use of

true muons, post FSR, and use of reconstructed muons to:

• Muon identification efficiency

• Momentum resolution...

Know this is high: 98%+


500GeV HZ Recoil, L=500fb-1

Mean RMS

mH 119,866.8 MeV

689.2 MeV

mH 645.6 MeV

87.3 MeV

nsig 11.03 % 1.08 %mH 119,793.7

MeV1,384.1

MeV

mH 1,322.9 MeV

339.1 MeV

nsig 16.68 % 2.75 %mH 120,041.0 MeV

2,528.7 MeV

mH 2,057.1 MeV

523.3 MeV

nsig 15.85 % 2.65 %

X

eeX

eeX

Brem

.

X

• Repeat recoil analysis at 500GeV with same code and procedures.

• Corrected initial state 4-vector since last time presented 500GeV analysis.


500GeV HZqq, L=500fb-1

• Model dependent analysis, with direct Higgs mass reconstruction: look for hadronic decay of H and Z.

• Force event into four jets (investigate different R values), perform kinematic fit and use B-tagging info in BDT selection.

R = 1.0


500GeV HZqq, L=500fb-1

Mean RMS

mH 119,993.7 MeV

100.7 MeV

mH 103.7 MeV

3.4 MeV

nsig 1.66 % 0.02 %mH 119,995.0

MeV99.5 MeV

mH 103.8 MeV

3.9 MeV

nsig 1.60 % 0.02 %mH 119,999.0

MeV117.4 MeV

mH 123.0 MeV

5.2 MeV

nsig 1.67 % 0.02 %

R =

0.7

R =

1.0

R =

1.3

R = 1.0

• Fluctuate high statistics signal sample, and smooth background fit, to produce 1000 test samples.


500GeV H, L=500fb-1

• Model dependent analysis, with hadronic decay of H and Z decaying to neutrinos.

• Previously, considered signal sample to be pure Higgsstrahlung, but cannot easily distinguish from WW-fusion process.

• Must consider new inclusive sample: hnunu

Implications for selection...

R = 1.3


500GeV H, L=500fb-1

Mean RMS

mH 120,034.7 MeV

95.3 MeV

mH 94.7 MeV

1.9 MeV

nsig 1.06 % 0.01 %mH 120,015.0

MeV98.3 MeV

mH 97.8 MeV

1.6 MeV

nsig 1.01 % 0.01 %mH 120,003.6 MeV

111.0 MeV

mH 111.2 MeV

2.3 MeV

nsig 1.05 % 0.01 %

R =

0.7

R =

1.0

R =

1.3

• Fluctuate high statistics signal sample, and smooth background fit, to produce 1000 test samples.

• Switch to inclusive hnunu sample introduces several awkward features. R = 1.0


500GeV H, L=500fb-1

R = 1.0

Full treatment of inclusive sample throughout analysis:

Consider only exclusive sample throughout analysis:

Train using exclusive sample, input “data” from inclusive sample:

R = 1.0R = 1.0

mH nsig

206.2 MeV 2.38 %

mH nsig

124.7 MeV 1.42 %

mH nsig

97.8 MeV 1.01 %

Status of the HZ Analyses

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