Phenomenology of Non-Abelian Gauge and Goldstone Bosons in a U(2) Flavor Model
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arXiv
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| Natura: | Preprint |
| Pubblicazione: |
2025
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| _version_ | 1866914470373097472 |
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| author | Calibbi, Lorenzo Yi, Jiangyi |
| author_facet | Calibbi, Lorenzo Yi, Jiangyi |
| contents | We investigate the phenomenological implications of the bosons associated with the $SU(2)_F$ subgroup in a simple and realistic $U(2)_F$ flavor model. While the Nambu-Goldstone boson of the $U(1)_F$ factor behaves as a standard QCD axion (an axiflavon) with suppressed flavor-violating couplings, the three degrees of freedom from $SU(2)_F$ have not been studied before. This work focuses on these states, considering both the case where $SU(2)_F$ is a global symmetry, yielding pseudo-Nambu-Goldstone bosons (PNGBs), and the case where it is a gauge symmetry with a potentially small coupling, yielding a triplet of (possibly) light gauge bosons. In both scenarios, these new bosons naturally feature unsuppressed flavor-violating couplings to Standard Model fermions in the mass basis. We derive the resulting predictions for flavor-changing neutral currents and lepton flavor violation, including exotic decays of mesons and leptons. Our analysis shows that processes like $K \to πX$ and $μ\to e X$ place the most stringent constraints, probing the flavor symmetry breaking scale $v_ϕ$ up to $10^{11}-10^{12}$~GeV for light bosons, while heavier states are tested in $B$ and $τ$ decays, as well as by $K-\bar K$ mixing and $μ\to e γ$. We demonstrate that low-energy flavor experiments provide a powerful probe of this framework, capable of testing ultra-high symmetry breaking scales that surpass the limits set by astrophysical observations. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2511_10468 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Phenomenology of Non-Abelian Gauge and Goldstone Bosons in a U(2) Flavor Model Calibbi, Lorenzo Yi, Jiangyi High Energy Physics - Phenomenology High Energy Physics - Experiment We investigate the phenomenological implications of the bosons associated with the $SU(2)_F$ subgroup in a simple and realistic $U(2)_F$ flavor model. While the Nambu-Goldstone boson of the $U(1)_F$ factor behaves as a standard QCD axion (an axiflavon) with suppressed flavor-violating couplings, the three degrees of freedom from $SU(2)_F$ have not been studied before. This work focuses on these states, considering both the case where $SU(2)_F$ is a global symmetry, yielding pseudo-Nambu-Goldstone bosons (PNGBs), and the case where it is a gauge symmetry with a potentially small coupling, yielding a triplet of (possibly) light gauge bosons. In both scenarios, these new bosons naturally feature unsuppressed flavor-violating couplings to Standard Model fermions in the mass basis. We derive the resulting predictions for flavor-changing neutral currents and lepton flavor violation, including exotic decays of mesons and leptons. Our analysis shows that processes like $K \to πX$ and $μ\to e X$ place the most stringent constraints, probing the flavor symmetry breaking scale $v_ϕ$ up to $10^{11}-10^{12}$~GeV for light bosons, while heavier states are tested in $B$ and $τ$ decays, as well as by $K-\bar K$ mixing and $μ\to e γ$. We demonstrate that low-energy flavor experiments provide a powerful probe of this framework, capable of testing ultra-high symmetry breaking scales that surpass the limits set by astrophysical observations. |
| title | Phenomenology of Non-Abelian Gauge and Goldstone Bosons in a U(2) Flavor Model |
| topic | High Energy Physics - Phenomenology High Energy Physics - Experiment |
| url | https://arxiv.org/abs/2511.10468 |