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CP Violation and Rare Decays in Hyperon and Charm Systems

CP Violation and Rare Decays in Hyperon and Charm Systems. NTU. Xiao-Gang He. Collaborators: Donoghue, Pakvasa, Tandean, Valencia. Antiproton Physics Workshop, Fermilab, 22 May, 2010. Outline. CPV in Hyperon Decays in the SM and Beyond HyperCP X Particle and Some Implications

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CP Violation and Rare Decays in Hyperon and Charm Systems

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  1. CP Violation and Rare Decays in Hyperon and Charm Systems NTU Xiao-Gang He Collaborators: Donoghue, Pakvasa, Tandean, Valencia Antiproton Physics Workshop, Fermilab, 22 May, 2010

  2. Outline • CPV in Hyperon Decays in the SM and Beyond • HyperCP X Particle and Some Implications • Charm Sector with New Physics

  3. Contributed to 4th International Symposium on Symmetries in Subatomic Physics, Taipei, Taiwan, 2-5 Jun 2009.

  4. CPV in Hyperon Decays in the SM and Beyond

  5. HyperCP X Particle and Some ImplicationsHyperCP’s findings • What’s the up-to-date SM prediction? Old calculation by Bergstrom, Safadi, Singer (1988) • Do the observed 3 events hint at new physics?

  6. From talk by HK Park (HyperCP) Interpretations of Results: S+ → pP0, P0 → m+m- Data MC: S+ → pm+m- S+ → pP0 , P0 → m+m-(MC) • Dimuon masses for 3 candidates are clustered within ~ 1 MeV/c2. • Probability for dimuon masses of 3 events to be within 1 MeV for S+ → pm+m- decays is less than 1%. • Suggests two-body decays, S+ → pP0, P0 → m+m-: Data

  7. Standard model expectations • Long-distance contributions dominate Σ+→pμ+μ−decay. • The resulting branching ratio He, JT, Valencia agrees well with the HyperCP measurement (under the assumption of no new physics) • The lower end of the predicted rate leaves room for attributing all the 3 observed events to new physics.

  8. Standard model expectations • Distribution of dimuon invariant mass Mμμ(solid curves) He, JT, Valencia • Different graphs reflect uncertainty in the calculation. • Not surprisingly, the predicted distributions show no sharp peak anywhere.

  9. New-particle interpretations • The possibility that a new particle, X, is responsible for the HyperCP events has been theoretically explored to some extent in the literature • X may be spinless • Pseudoscalar sgoldstino in supersymmetric models Gorbunov et al. • CP-odd Higgs boson in the next-to-minimal supersymmetric standard model (NMSSM) He, JT, Valencia • X may be a spin-1 particle • Gauge (U) boson of an extra U(1) gauge group in some extensions of the SM. Chen, Geng, Kao He, JT, Valencia Deshpande, Eilam, Jiang Geng, Hsiao . . . . .

  10. Constraints on bbXcouplings for spinless X • CLEO • BaBar

  11. Constraints from K  π  μ+μ−data • With only the 2-quark contributions being present, the scalar gS (vector gV) part of the sdX coupling in the spinless (spin 1) case is constrained by K π  μ+μ−data to be negligibly small. • The pseudoscalar gP (axial-vector gA) part can be probed by Kππμ+μ− He, JT, Valencia Deshpande, Eilam, Jiang NTU PPJC, 7 Dec 2009

  12. Search for KLπ0π 0X, Xγγ • This constrains some sgoldstino scenarios.

  13. Searches for KLπ0π 0X, Xμ+μ− • Preliminary results reported at KAON09

  14. From talk by D Phillips (KTeV)

  15. Implications of KTeV results • KTeV measurements • Same number for spinless or spin-1 X • Predictions for spin-1 X(with real sdX coupling) He, JT, Valencia • This is well below the KTeV upper-bound and could get lower in the presence of an imaginary part of the sdX coupling • Thus the axial-vector (gA) part the sdX coupling is not well constrained From talk by D Phillips (KTeV)

  16. Search for B 0 K *0X, ρ0X, Xμ+μ− at Belle From talk by H Hyun (Belle) 29

  17. Charm Sector with New Physics

  18. Divergences treated by dimensional regularization with a cut off

  19. Large contributions to D^0 – \bar D^0 mixing and CP violation. c -> u gamma. ….

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