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  • Open Access

Dirac leptogenesis in left-right symmetric models

K. S. Babu* and Ajay Kaladharan†

  • *Contact author: babu@okstate.edu
  • †Contact author: kaladharan.ajay@okstate.edu
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Phys. Rev. D 112, 035015 – Published 12 August, 2025

DOI: https://doi.org/10.1103/kxvb-l4gb

Abstract

Left-right symmetric models which employ a generalized seesaw mechanism to generate quark and charged lepton masses are known to solve the strong CP problem via parity symmetry, without the need for the axion. These models lead to naturally light Dirac neutrinos with their masses arising through radiative corrections. In this work, we show how baryogenesis via Dirac leptogenesis can be implemented in this framework. A pair of left-right symmetric scalar doublets ϕL,R carrying (B−L) charge of 3 is introduced for this purpose, which preserves the parity solution to the strong CP problem. Small neutrino masses are generated through one-loop diagrams mediated by these scalars. The decay of vectorlike leptons (Ei) involved in the seesaw mechanism to generate charged lepton masses, Ei→ν¯jRϕR−, creates a right-handed neutrino (νR) asymmetry, while preserving total lepton number. The compensating lepton asymmetry is converted to baryon asymmetry via electroweak sphalerons. We show that for a large range of model parameters successful baryogenesis can be realized, with the WR± gauge boson mass of order 1011  GeV.

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Phys. Rev. D 112, 035015– Published 12 August, 2025
  • Received 8 November 2024
  • Revised 16 July 2025
  • Accepted 21 July 2025
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Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. Funded by SCOAP3.

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