Beyond neutrino mass: observable $n$-$\bar{n}$ oscillations in UV complete seesaw models

Doršner, Ilja (author), Fajfer, Svjetlana (author), Saad, Shaikh (author)

Next-generation experiments, such as the Deep Underground Neutrino Experiment and the European Spallation Source, are set to improve sensitivity to neutron-antineutron oscillation, a direct probe of ∆B = 2 baryon number violation, with particularly significant gains expected at the latter. The discovery of such a rare ∆B = 2 process would indicate physics beyond the Standard Model and could point to specific unified theories that allow observable ▫$n$▫-▫$\bar{n}$▫ transitions. We accordingly examine ▫$n$▫-▫$\bar{n}$▫ oscillations within a unified framework that accounts for charged fermion masses and generates viable neutrino masses via the seesaw mechanism. More specifically, we show that ▫$n$▫-▫$\bar{n}$▫ oscillations can arise from two specific topologies within two distinct SU(5) scenarios. One topology requires a presence of two color-sextet scalars in the Type II seesaw framework, whereas the other involves a scalar sextet and a color-octet fermion in the Type III seesaw framework. While the former topology can be realized in the SO(10)/Pati-Salam frameworks, the latter finds a natural embedding in SU(5), which constitutes one of the key novelties of our work. Remarkably enough, the same dynamics responsible for fermion masses also induces baryon number violation, thus linking ▫$n$▫-▫$\bar{n}$▫ oscillations to the flavor structure of the theory. We show that, given a TeV-scale mass for one of the colored states, upcoming searches for such ∆B = 2 processes can probe for a presence of the other colored states with masses up to 1011 GeV, well beyond the reach of colliders. This positions ▫$n$▫-▫$\bar{n}$▫ oscillations as a rare low-energy portal to grand unification and ultra-heavy new physics.

• Language: English
• Keywords: physics of elementary particles
• Work type: Article
• Typology: 1.01 - Original Scientific Article
• Organization: FMF - Faculty of Mathematics and Physics
• Publication status: Published
• Publication version: Version of Record
• Year: 2025
• Number of pages: 26 str.
• Numbering: Vol. 2025, art. no. 24
• PID: 20.500.12556/RUL-175882
• UDC: 539.1
• ISSN on article: 1029-8479
• DOI: 10.1007/JHEP11(2025)024
• COBISS.SI-ID: 256728579
• Publication date in RUL: 12.11.2025

Record is a part of a journal

• Title: The journal of high energy physics
• Shortened title: J. high energy phys.
• Publisher: SISSA
• ISSN: 1029-8479
• COBISS.SI-ID: 1314148

Licences

• License: CC BY 4.0, Creative Commons Attribution 4.0 International
• Link: http://creativecommons.org/licenses/by/4.0/
• Description: This is the standard Creative Commons license that gives others maximum freedom to do what they want with the work as long as they credit the author.

Secondary language

• Language: Slovenian
• Keywords: fizika osnovnih delcev

Projects

• Funder: ARIS - Slovenian Research and Innovation Agency
• Project number: P1-0035-2019
• Name: Teorija jedra, osnovnih delcev in polj

• Funder: ARIS - Slovenian Research and Innovation Agency
• Project number: N1-0321-2023
• Name: Obarvani skalari v fiziki onkraj standardnega modela