SciPost Submission Page
Fractionally Charged Particles at the Energy Frontier: The SM Gauge Group and One-Form Global Symmetry
by Seth Koren, Adam Martin
Submission summary
| Authors (as registered SciPost users): | Seth Koren |
| Submission information | |
|---|---|
| Preprint Link: | scipost_202407_00013v1 (pdf) |
| Date submitted: | 2024-07-08 16:48 |
| Submitted by: | Koren, Seth |
| Submitted to: | SciPost Physics |
| Ontological classification | |
|---|---|
| Academic field: | Physics |
| Specialties: |
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| Approaches: | Theoretical, Phenomenological |
Abstract
The observed Standard Model is consistent with the existence of vector-like species with electric charge a multiple of $e/6$. The discovery of a fractionally charged particle would provide nonperturbative information about Standard Model physics, and furthermore rule out some or all of the minimal theories of unification. We discuss the phenomenology of such particles and focus particularly on current LHC constraints, for which we reinterpret various searches to bound a variety of fractionally charged representations. We emphasize that in some circumstances the collider bounds are surprisingly low or nonexistent, which highlights the discovery potential for these species which have distinctive signatures and important implications. We additionally offer pedagogical discussions of the representation theory of gauge groups with different global structures, and separately of the modern framework of Generalized Global Symmetries, either of which serves to underscore the bottom-up importance of these searches.
Author indications on fulfilling journal expectations
- Provide a novel and synergetic link between different research areas.
- Open a new pathway in an existing or a new research direction, with clear potential for multi-pronged follow-up work
- Detail a groundbreaking theoretical/experimental/computational discovery
- Present a breakthrough on a previously-identified and long-standing research stumbling block
Current status:
Reports on this Submission
Report
The paper presents a thorough investigation into the phenomenology and implications of fractionally charged particles within SM. If we discover such particles, it would have important implications, offering nonperturbative insights into SM physics and potentially challenging some grand unified theories. The authors emphasize the relevance of searching for these particles, particularly at high-energy colliders like the LHC.
The study carefully examines production mechanisms for these particles at the LHC, considering Dirac fermions and complex scalars in various representations of the SM gauge group. The authors provide detailed analytic expressions for production cross-sections in various cases, highlighting the dependence on the particles' quantum numbers and the energy scale. This analysis is clear and informative.
In discussing collider signatures, the authors reinterpret existing LHC searches, particularly those by CMS and ATLAS, to place bounds on various scenarios. They address the challenges in detecting low-charge particles, suggesting that more targeted experimental strategies may be needed. The interpretation of LHC bounds is reasonably handled, with specific mass limits provided for different representations, though some cases indicate that the current experimental constraints are weaker than expected.
The cosmological implications of discovering fractionally charged particles are also briefly discussed, noting how such a discovery could impact the understanding of relic abundances and the reheating temperature after inflation. This adds context to the study, though it is not the central focus.
The sections on the global structure of gauge theory and generalized global symmetries offer a solid theoretical foundation, exploring how different structures of the SM gauge group could accommodate fractionally charged particles. These discussions are informative and contribute to the overall understanding of the topic. Although the generalized symmetry discussion does not seem to provide new insights, the systematic presentation is sufficiently useful and interesting.
Overall, the paper provides a comprehensive analysis of the production, detection, and implications of fractionally charged particles. I recommend the paper for publication.
Recommendation
Publish (surpasses expectations and criteria for this Journal; among top 10%)