High Energy Physics Seminars

Leptonic CP phase test for Left-Right Symmetric Model

by Dr. Ravi Kuchimanchi (Association for India’s Development)

Friday, February 9, 2018 from to (Asia/Kolkata)
at TIFR, Mumbai ( D-406 )
TIFR, Mumbai
Description
Left-Right symmetric model (LR model) is one of the most popular models that historically anticipated neutrino masses. It restores Parity (P) as a good symmetry of the Lagrangian and thereby also sets the Strong CP phase to zero in the symmetry limit. However this phase is generated when parity is spontaneously broken and can be calculated in terms of the other parameters of the Lagrangian. I show that in the minimal LR model, CP violation in the Leptonic Yukawa sector can radiatively generate the strong CP Phase in one loop. This would then contribute to the neutron EDM well beyond the current limits. Therefore the leptonic Dirac CP phase that is currently being probed by neutrino experiments must be absent (mod /pi) in significant regions of the parameter space of the minimal LR model. The result holds even if the seesaw scale (parity and B-L breaking scale) is at its canonical value of 1015 GeV, well beyond the reach of colliders. This is thus an exciting way to test the LR model all the way upto this high scale. I will also discuss a strong CP solution using P and CP that completes the LR model in the ultra-violet. Another exciting feature of parity models is that the Z_2 symmetry that stabilizes dark matter can be an automatic consequence of P, since P^2 = Z_2.