Light Higgs Production at the Tesla Photon Collider

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Light Higgs Production at the Tesla Photon
Collider

• Aura Rosca
• DESY Zeuthen
• Amsterdam, Netherlands, 1-4 April 2003

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Motivation

• Measure the two-photon partial width
• Contribution to the two photon decay width from
  any kind of massive charged particles. Any
  deviation of the partial width from SM
  prediction
• Evidence for new physics
• Can be directly compared to predictions of
  alternative models (MSSM, NMSSM, general 2HDM).

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How to Get Widths?

• The Higgs mass peak gives
• Taking and
  from LHC or LC,
• This is proposed as the way to get the total
  width. This would be a model-independent result.

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Realistic Luminosity Spectra and Polarization for
the Photon Beams

Circe 2.0

• Luminosity spectra for J0,2 with
• Total luminosity for

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The Signal

• Adjust beam polarization to increase the signal
  cross section
• If know, adjust photon energies to have
  .

• Higgs boson has spin-0
• It is produced from J0

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Higgs Decay

• Light Higgs
• Signature
• 2-jet events
• Background
• large cross sections, can be suppressed
  exploiting the polarization dependence of the
  cross section.

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The Background

• Suppression removed for
• Need to take into account the NLO corrections!

Need b-tag to reduce bkg.
Photons of the same helicity suppress
continuum
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Background Cross Sections

• NLO cross sections include
• Exact one-loop QCD corrections (Jikia, Tkabladze)
• Non-Sudakov form factors (Melles, Stirling, Khoze)

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Simulation

• Results include realistic photon spectrum for
  and - helicities simulated with Circe 2.0
• Signal MC generated with Pythia and passed
  through the TESLA fast simulation, Simdet 4.02
• Background MC generated with Pythia and passed
  through the TESLA fast simulation
• Convolution with the realistic photon spectrum
  for and - helicities
• Events weighted by the NLO Xsec for and -
  helicities
• B-tagging

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Cross Sections
Cross section (pb) Number of expected ev. Number of generated ev.
Signal process 0.25 20 000 50 000
Background J0 (from Pythia) 0.75 44 175.0 600 000
J2 4.79 102 314.4 600 000
J0 13.4 789 260.0 600 000
J2 85.1 1 817 734.0 600 000
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Selection Requirements

• Isotropic angular distributions for signal and
  forward peaked for the background
• Jet clustering using Durham with y0.02
• Other cuts on

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B-tagging Performance
Events containing at least one jet with two
reconstructed vertices
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Invariant Mass Spectrum

• It is possible to isolate the signal from the
  background.

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Partial Width Uncertainty

• This is one of the main justifications for a
  Photon Collider.

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Summary

• Measure with a
  precision of 1.9 by
• Taking into account the QCD radiative corrections
  to the background process (Pythia
  NLO Xsec.) through a reweighting procedure
• Adopting a b-quark tagging algorithm based on a
  neural network.

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Summary

• Measure with a
  precision of 1.9 by
• Taking into account the QCD radiative corrections
  to the background process (Pythia
  NLO Xsec.) through a reweighting procedure
• Adopting a b-quark tagging algorithm based on a
  neural network.