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Exploring Fourth Generation Particles and Direct CP Asymmetries in Kaon Decays

This paper discusses the implications of a potential fourth generation of fermions in the Standard Model, focusing on how it may enhance the electroweak (EW) penguin contributions and explain recent experimental data regarding direct CP violation in Kaon decays. A theoretical framework is presented which suggests the existence of heavier particles with masses on the order of the electroweak scale, while addressing constraints from electroweak precision measurements and proposing scenarios that could accommodate neutral fermions. The findings indicate that a fourth generation remains a plausible extension of the Standard Model.

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Exploring Fourth Generation Particles and Direct CP Asymmetries in Kaon Decays

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  1. B+ and B0 Direct CP Asymmetries difference in a sequential Fourth Generation scenario Andrea Soddu Weizmann Institute Corfu 2005 September 4th – 11th 2005 W.-S. Hou, M. Nagashima, A.S. hep-ph/0503072, to appear on PRL hep-ph/0508237

  2. Outlook A world with more than three families still plausible scenario B decays in K p suggest the possibility of a big C or a big PEW A 4TH generation is a natural extension of the SM with an enhanced PEW PQCD framework (LO) + 4TH generation seems to explain experimental data Implications of a big PEW for the Kaon sector Conclusions

  3. It is natural to have particles with mass of order EW scale Existence of a 4TH generation: U, D, N, E Fit to EW precision data is still not good Existence of a 4TH generation with all fermions heavier than strongly disfavored by EW precision data One and even two generations are allowed when neutral fermions are relatively light N strongly decoupled from the three light neutrinos to avoid constraint from LEP II M. Maltoni V.A. Novikov, L.B. Okun, A.N. Razanov and M.I. Vysotsky

  4. Direct CP Violation

  5. Y.Y. Charng and H-n Li A.J. Buras, R. Fleisher, S. Recksiegel and F. Schwab Can SM4 realize one of the 3 possible scenarios?

  6. New Physics AH…AH…AH… QCDF AH…AH…AH…

  7. Factorizable Non Factorizable

  8. Factorizable Non Factorizable EWP

  9. measured from unitarity

  10. SM 3 SM 4 new unitarity condition new penguin from t’

  11. Effective Feynman Rules

  12. tree QCD penguin EW penguin naturally enhanced in SM 4 EW penguin

  13. New Avg. PDG04

  14. A. Arhrib and W.-S. Hou T. Hattori, T. Hasuike and S. Wakaizumi T. Yanir

  15. safe ? safe ?

  16. Double Cabibbo CKM Matrix

  17. Conclusions SM 4 not excluded by electroweak precision data Electroweak Penguin naturally enhanced in SM 4 PQCD LO + 4TH generation can explain data for K p strongly constrain VCKM highly enhanced in SM 4 PQCD NLO + 4TH generation could be a very plausible scenario without the need to stretch C and PEW

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