Measurement of the Higgsbosons parity at TESLA

1
Measurement of the Higgs-bosons parity at TESLA

• Andreas Imhof1,2
• Klaus Desch2, Thorsten Kuhl1 and Malgorzata
  Worek3
• 1 Deutsches Elektronen-Synchrotron DESY
• 2 University of Hamburg
• 3 Silesia University, Katowice, Poland

2
Contents

• The observable
• Conditions for a measurement at TESLA
• Some aspects of the applicability
• First results from the reconstructed observable

3
The observable

• For the ?-decays into 2 or 3 pions via ?-, or a1-
  resonances
• The momenta of the pions in the final state span
  planes
• Correlation sensitive to Higgs-parity
• the acoplanarity ?.

4
The observable

• Problem ambiguity for the measurement
• Additional criteria ?-energies
• 2 classes of events with
• y1y2 lt 0 or y1y2 gt 0
• Implementation for y1y2 lt 0 acoplanarity
  2? - ?
• ? one distribution for both classes

5
Theoretical distributions
and mixed channel ?1 ? ??? , ?2 ? a1? ? ? ? ??0
?
6
Boundary conditions

• Limited statistics of these channels
• e.g. for and
• ? together approx. 500 events per 350 fb-1
• Detector-resolution and -efficiency ? use SIMDET
• Efficiency of the analysis
• Separation of signal from background (not
  included yet)

7
Aspects of final-state-reconstruction

• for ?? ? ??? ? ???0?
• ?0 ? ??
• how to reconstruct the ?0 ?
• red line shows angle,
• required, that 2 photons
• hit the ECAL with 3 cm
• distance
• granularity not properly
• implemented in Simdet.

8
Aspects of final-state-reconstruction
?? -reconstruction
ambiguity in 3-prong-final-state
9
Tree vs. reconstructed
solid MC-data dashed SIMDET-rec

• for 150 years of TESLA-running.....

10
Distributions for 1000 fb-1

• Observable is independent of the
  production-process.
• Here as example SM-Higgstrahlung ee- ? Z0H0
  ?X??-
• with vs 350 GeV and mH 120 GeV

Nevt 833 Nevt 666 Nevt
133
11
Asymmetry of ?

• From large number of events with scaled errors

12
Combined result

• Acoplanarities
• H0 0.118 ? 0.026
• A0 -0.113 ? 0.026
• ? gt 8 s at this point of the analysis

13
Conclusion

• Acoplanarity sensitive to CP-eigenstate of the
  Higgs-bosons
• ?-?- and a1-?-channel allow measurement of the
  parity
• a1-a1-channel looks worse
• Still missing background-studies
• Improvements possible, e.g. corrections on
  missing transverse neutrino-impuls
• SIMDET-ECAL-description too simple, need
  BRAHMS-study for ?0
• start systematic ?-identification for TESLA