# Presentation: 548082

## H4l in Full Simulationpreliminary  results 2

- A. Khodinov* and K. Assamagan**
- 	* State University of New York at Stony Brook
- 	** Brookhaven National Laboratory

## Data set (signal only)

- Z(*)e+e-
- Z(*)+-

- hZZ(*)
- mh = 130 *GeV*

- h4e	
-  	h4
- 		h2e2

## Framework details

-  Number of Events 		100.000
-  Generator			Pythia 6.217 (6.5.0)
-       no filters
-  Fully simulated with 		ATLSIM (6.5.0)
-  VDC dataset 		simul_000033
-  geometry level		dc1 ()
- Reconstructed with		ATHENA (7.0.2)
- Job Options file		RecExCommon_jobOptions.txt
- Additional MC Truth		Spcl_MC (F.Paige and I.Hinchliffe)

## Lepton Reconstruction

- We suppose to compare 2 alternative methods matching tracks in the Inner Detector with Muon Spectrometer.
- STACO (statistical combination) MuonBox + Xkalman
- 	( planned to be included in the ATLAS software release. When?).
- 	so currently use **ONLY MuonBox**
- 	Ref: Muon reconstruction with Muonbox and STACO by _[Hassani](mailto:Samira.Hassani@cern.ch)__[, S.](mailto:Samira.Hassani@cern.ch)_  *(Saclay)*
- 2.    MuID combined (already in the release)
- 	Moore + IPatRec
**	**Ref: Muon reconstruction with Moore and MuID by Biglietti M., Cataldi G. (Naples University, INFN Lecce)
**STACO **&** ****Muid Comb**: Combination of the muon system and the inner detector tracks
- “**MuonBox**” & “**MuidStandAlone**” : Back tracking of the MuonBox and MOORE tracks to the interaction point

## Kinematical cuts as in TDR

- e1+ e2- or +- with pT>20 GeV (leading pair*)
- 	e3+ e4- or +- with pT>7 GeV  (following pair)
- 2. Calculate invariant Z mass
- m12  = mZ ****** **15** **GeV**  **or ( 6 GeV)
- m34  >        20** **GeV
- Using these cuts the best result obtained was =2.1 GeV (MUID Comb)
**We show improvement since our last meeting in November**
**We will show results for H********4e and H******** 2e 2******** also!**

## Additional requirements (Our own)

- TRD + combinatorial treatment
- Instead of taking just the 2 hardest leptons as
-  the leading pair, we look though all the possible
- 4 lepton combinations for the leading and following
- pairs but retain the combination where the leading pair
- is best reconstructed (we do not require hardest pTs):
**e****1****+**** ****e****2****- ****or ************+************-**** with p****T****>20 GeV  ****min(M****z****-**** ****M****ld****)**

**Doing the above, our best resolution improves**
**from ********=2.1 GeV to ********=1.8 GeV (MUID Comb)**

## Additional Requirements our own

-  2. Z-mass constraint
- Assuming the 2 leading leptons come from an on-shell Z of mass m0, rescale the lepton 4-momentums such that:
-        **p ******** p*m****0****/m****ll**
-   Where mll is the measured (reconstructed) invariant mass of the 2 leading leptons
- Do this before reconstructing the H mass
- To find m0, we do this on event by event basis: convolute detector resolution with the Breit-Wigner shape for the Z:
-      m0 = max ( Gaussian(mll, 0) * BW(mZ,Z) )
-   where 0 is the detector resolution by plotting mll
-    without the mass constraint

## Improvement from 2.1 GeV

- h4

**without mass constraint ******** =1.8 GeV**

**without mass constraint ********  =2.9 GeV**

- Leading Mll cut = Mz+-15 GeV
- Mass constraint applied

- to 1.8 GeV with the handing
- of combinatorial as described

- mean  129.9
- 

- mean  130.2
- 

- mean  130.2
- 

## h2e2

**Without mass constraint ******** IPat =2.85 GeV**

- 2.7
- Norm calorimeter factor =1/0.9845

- MC Isol Cut   5 GeV
- ET cut	 15 GeV
- track match   YES

- h2e2

- h4e

- h4e

- Leading Mll cut =Mz+-15 GeV

- mean  129.9
- 

- mean  129.9
- 

- mean  129.8
- 

## Z (*) +-  reconstruction by MuID Comb

- Z (*) +-  reconstruction by MuID Comb

## h4

- Leading Mll cut = Mz+-6 GeV
- Mass constraint applied

- h4

- mean  129.8
- 

- mean  130.2
- 

- mean  130.2
- 

## Leading Mll cut = Mz+-6 GeV

- Leading Mll cut = Mz+-6 GeV
- Mass constraint applied

- 2.7
- Norm calorimeter factor =1/0.9845

- mean  129.9
- 

- mean  129.9
- 

- mean  129.9
- 

## Problem in calibration for

- electrons:
- The normalization factor of 1/0.9845
- required to restore the 4 momentum of reconstructed electrons

- Z (*) e+e-

## Summary of our results

| Process | Reconstructed mean (GeV) | Sigma (GeV) |
| --- | --- | --- |
| Muid CB     H  4 | 130.2 | 1.56 |
| CB + IPat   H  2e | 129.9 | 1.89 |
| Ipat H  4e | 129.9 | 1.83 |

-  all the new H4 analyses using Muid CB, we have the best      resolution (see the Higgs Working Group meetings)
- Our H2e2 results are in agreement with Wisconsin Group (see the talk
-  Steve Armstrong in the Higg group)
-  Our H4e result compare well with Wisconsin result (see the talk by Stathes Paganis : he has worked on electron calibration!)

## Summary and plans

- MuID combined provides better resolution than MuId stand alone, so we are awaiting for STACO to implement into the analysis.
- Photos + filters on  is required to simulate Brem properly (Pythia itself does not provide right Brem) and increase the statistics of ‘good’ reconstructed Higgs bosons.
- Analysis tuning is planned (mostly h4e and h2e2)
- A look at backgrounds: electron, muon isolations
- We will obtain and use the electron calibration done recent by the Wisconsin Group (see the talk by Stathes Paganis in the Higgs Working Group!)