Saving fourth generation and baryon number by living long

Abstract

Recent studies of precision electroweak observables have led to the conclusion that a fourth generation is highly constrained. However, we point out that a long-lived fourth generation can reopen a large portion of the parameter space. In addition, it preserves baryon and lepton asymmetries against sphaleron erasure even if $B-L=0$. It opens up the possibility of exact $B-L$ symmetry and hence Dirac neutrinos. The fourth generation can be observed at the LHC with unique signatures of long-lived particles in the near future.

4 pages, 3 figures

References in corpus (4)

• Stable Massive Particles at Colliders
• Precision Constraints on Extra Fermion Generations
• Search for Long-Lived Massive Charged Particles in 1.96 TeV $\bar{p}p}$ Collisions
• Baryogenesis from an Earlier Phase Transition

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• Lepton Number Conservation, Long-lived Quarks and Superweak Bileptonic Decays