1 / 28

η and π 0 Decay to Two Neutrinos

η and π 0 Decay to Two Neutrinos. Ali R. Fazely Department of Physics Southern University Miami Conference, 2007. In collaboration with. Richard L. Imlay, Samvel Ter-Antonyan, Kevin Muhammad Department of Physics Southern University. Do η or  0 decay into two neutrinos?

tamma
Download Presentation

η and π 0 Decay to Two Neutrinos

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. η and π0 Decay to Two Neutrinos Ali R. Fazely Department of Physics Southern University Miami Conference, 2007

  2. In collaboration with Richard L. Imlay, Samvel Ter-Antonyan, Kevin Muhammad Department of Physics Southern University

  3. Do η or0 decay into two neutrinos? • Standard Model: 0  νν or η νν is forbidden, except for massive neutrinos. • The experimental search for such purely NC decays would shed light on the nature of neutrinos and weak processes.

  4. Weak Current • The +  e + + e has a BR of 1.23  10-4 (pdg) The helicity is broken due to the mass of the electron consistent with the V-A interaction.

  5. o   Forbidden in V-A Interaction o is 0- and vacuum is 0+ For massless neutrinos 0-  0+ transition is allowed only if Pseudoscalar (P) is present Same for   

  6. The rate for A and P • The decay rate for A interaction is proportional to (1 -  ). For massless neutrinos  = 1 and the rate is zero. • The decay rate for P interaction is proportional to (1+  ). For massless neutrinos  = 1 and the rate is maximum.

  7. The rate for A and P • A-coupling: BR = π→ eνe/π→μνμ = (me/mμ)2[1/(1- mμ2/mπ2)2] = 1.275×10-4 • P-coupling: BR = π→ eνe/π→μνμ = 1/(1- mμ2/mπ2)2 = 5.5

  8. Experimental results on ηνν and0 νν l+ q Z0 Within the SM, the diagram is a simple qq annihilation to lepton pairs through a Z0 propagator. l- q-

  9. Decay Rate Arnellos, Marciano, Parsa, Nucl Phy B196 (1982)

  10. Experimental Results LSND pdg, all at 90% CL

  11. LSND Results PRL 92, 4, 091801-1, hep-ex/0310060 • Observation of a muon-like, beam-excess above 160 MeV in the LSND detector • 8.7 ± 6.3 (stat) ± 2.4 (syst) beam-excess events (pdg) • The possible Branching Ratio of is:

  12. π0 ντντ A 95% CL, upper limit of <18.2 MeV was set by the ALEPH Collaboration on ντmass from 3 and 5-prong τ decay. (Eu J Phys, 1998, pdg). However, (mτ/m)2 < 331.24/(134.9)2≈ 0.0182

  13. π0 ντντ Therefore, Γ(π0 ντντ)/Γ(π0 all) < 5.0 × 10-10, assuming no exotic mechanisms! A possible laboratory to set limits on the ντ mass!

  14. η νν (90%CL) pdg, BES2 collaboration, 06Q PRL 97 202002

  15. muons neutrons Electrons/positrons Photons, from 0 and η

  16. Estimates for the BR of the Km3Detectors, e.g. IceCube • Dominant interaction inside the ice is: • The signature is an electron or τ cascade event

  17. Primary FluxSolid and dashed lines are those of Gaisser & Honda,(hep-ph/0203272 (2002)). Symbols are from spectra of Wiebel, Bierman & Meyer, Ast. And Astrophys. 330 (1998), used in our CORSIKA simulations

  18. Atmospheric Neutrino Flux, CORSIKA

  19. Detected Spectra

  20. Branching Ratio vs. Energy,5-year run

  21. Branching ratio vs. Years

  22. Conclusions • Limits can be set for the first time on ηνν with KM3 detectors • νν limits would not be competitive with existing limits. • Dedicated experiments can be designed to look for ντντ yielding limits on the ντmass as well as any possible P interaction.

More Related