1. TESLA - The TEV-Energy Superconducting Linear Accelerator Towards a measurement of the two photon width of the Higgs boson at the Tesla Photon Collider Aura Rosca West University, Timişoara, Romania Durham, U.K., 1-4 September 2004

2. TESLA - The TeV-Energy Superconducting Linear Accelerator September 2004Aura Rosca West University Timisoara2 Motivation Measure the two-photon partial width: –Contribution to the two photon decay width from any kind of massive charged particles. Deviation of the partial width from Standard Model prediction: Evidence for new physics; Can be directly compared to predictions of alternative models (MSSM, NMSSM, general 2HDM).

3. TESLA - The TeV-Energy Superconducting Linear Accelerator September 2004Aura Rosca West University Timisoara3 How to Get Widths? The Higgs mass peak gives Taking and from LHC or LC, This is proposed as way to get the total Higgs width. Model-independent result.

4. TESLA - The TeV-Energy Superconducting Linear Accelerator September 2004Aura Rosca West University Timisoara4 Results of Amsterdam ‘03 Realistic photon spectrum for ++ and +- photon 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 +- photon helicities –Events weighted by the NLO (Jikia, Tkabladze) cross sections for ++ and +- photon helicities B-tagging based on NN

5. TESLA - The TeV-Energy Superconducting Linear Accelerator September 2004Aura Rosca West University Timisoara5 Invariant Mass Spectrum Possible to isolate the signal from the background.

6. TESLA - The TeV-Energy Superconducting Linear Accelerator September 2004Aura Rosca West University Timisoara6 New Results Background MC generated with SHERPA (CERN-TH/2003-284) and passed through the TESLA fast simulation: – –Convolution with the realistic photon spectrum for ++ and +- photon helicities Selection: – New!

7. TESLA - The TeV-Energy Superconducting Linear Accelerator September 2004Aura Rosca West University Timisoara7 80100120140160 Background Cross Sections 80100120140160 1.9 2.8 0.9 0.99

8. TESLA - The TeV-Energy Superconducting Linear Accelerator September 2004Aura Rosca West University Timisoara8 Sherpa versus Pythia Pythia ++ Sherpa ++ Pythia +- Sherpa +-

9. TESLA - The TeV-Energy Superconducting Linear Accelerator September 2004Aura Rosca West University Timisoara9 Sherpa versus Pythia Pythia ++Pythia +- Sherpa ++Sherpa +-

10. TESLA - The TeV-Energy Superconducting Linear Accelerator September 2004Aura Rosca West University Timisoara10 Sherpa versus Pythia Pythia ++Pythia +- Sherpa ++Sherpa +-

11. TESLA - The TeV-Energy Superconducting Linear Accelerator September 2004Aura Rosca West University Timisoara11 Sherpa versus Pythia Pythia ++Pythia +- Sherpa ++Sherpa +-

12. TESLA - The TeV-Energy Superconducting Linear Accelerator September 2004Aura Rosca West University Timisoara12 Invariant Mass Spectrum (However, more statistics required!)

13. TESLA - The TeV-Energy Superconducting Linear Accelerator September 2004Aura Rosca West University Timisoara13 Summary Measure with a precision below 2% by: –Taking into account the QCD radiative corrections to the background process ; –Adapting a b-quark tagging algorithm based on a neural network.