Gauge invariant electromagnetic properties of fermions induced by <i>CPT</i>-violation in the Standard Model Extension

Moyotl, A.; Novales‐Sánchez, H.; Toscano, J. J.; Tututi, E. S.

doi:10.1142/s0217751x14500390

Cited by 26 publications

(23 citation statements)

References 55 publications

(79 reference statements)

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“…85 and radiative corrections. [86][87][88][89][90][91][92][93] Though the minimal SME is constructed by adding to the SM Lagrangian new observer Lorentz invariant objects of the form described above, which are renormalizable in the Dyson's sense, it can be enlarged to include nonrenormalizable interactions.…”

Section: -52mentioning

confidence: 99%

“…In this paper we will follow an alternative approach by treating this CP T -odd effect as a perturbation, 91 for this class of new physics is expected to be minuscule. The purpose of this work is twofold, as, for one side, we will estimate the size of these couplings, whereas, on the other side, we will take advantage of this problem to illustrate how to carry out radiative corrections in the context of the SME, which, unlike conventional renormalizable theories, becomes a formidable task.…”

Section: -90mentioning

confidence: 99%

“…In this paper, we shall adopt a perturbative approach, which consist in assuming standard propagators and freefield solutions. The bilinear CP T -violating effect is treated by inserting the iλ/ bγ 5 vertex in each fermionic line 91 of triangle diagrams that contribute to the Z → γγ and Z → gg decays, as it is shown in Fig. 1.…”

Section: -90mentioning

confidence: 99%

“…1. As it can be appreciated from this Figure, the term that introduces CP T violation has been incorporated via an insertion in each fermionic line, 91 so the particles circulating in the loop can be described by propagators which emerge from adding to the standard propagator the insertion of the anomalous vertex:…”

Section: Decay Z → γγmentioning

confidence: 99%

See 3 more Smart Citations

Decays Z → γγ and Z → gg in the Standard Model Extension

Castro-Medina

Novales‐Sánchez

Toscano

et al. 2015

Int. J. Mod. Phys. A

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The Z → γγ and Z → gg decays are studied in the context of the renormalizable version of the Standard Model Extension. The CP T -oddψγ 5 / bψ bilinear interaction, which involves the constant background field bα and which has been a subject of interest in literature, is considered. It is shown that the Z → γγ and Z → gg decays, which are strictly zero in the standard model, can be generated radiatively at the one-loop level. It is found that these decays are gauge invariant and free of ultraviolet divergences, and that the corresponding decay widths only depend on the spatial component of the background field b. IntroductionThe trilinear V V V (V = γ, Z) and quartic V V V V neutral couplings are quite suppressed, as they first arise at the one-loop level a in the Standard Model (SM) and in most of its renormalizable extensions. Since new physics effects could be more apparent in those processes which are quite suppressed or forbidden in the SM, these couplings constitute a good mechanism for investigating possible signals of physics beyond the Fermi scale. The charged counterparts W W V and W W V V , of these neutral couplings, arise at the tree level and are related by gauge invariance in the sense that they are simultaneously induced by1, 2 However, this type of gauge connection does not exist between the V V V and V V V V couplings.3, 4 While the V V V V couplings receive one-loop contributions from both fermionic and bosonic particles b , the V V V ones are exclusively generated by fermionic triangles.38-40 Intimately related with the absence of a gauge link between the V V V and V V V V couplings is the fact that none of the V V V vertices reflects the non-Abelian nature of the electroweak group, as the Yang-Mills sector neither induces these couplings at the tree-level nor contribute to them at the one-loop order. This is in contrast with the quartic V V V V couplings, which are generated by the Yang-Mills sector at the one-loop level.5-37 The trilinear V V V couplings are indeed severely restricted by the Bose and Lorentz symmetries. It turns out that if both Bose symmetry and Lorentz invariance are simultaneously respected, the V V V coupling vanishes when the three bosons are real, though they can exist when at least one of the particles is off-shell.38-40 As a consequence, the Z → γγ decay is forbidden. This result is known as the Landau-Yang's theorem, 41,42 which establishes that a vector particle cannot decay into two massless vector particles. This means that the Z decay into two gluons is also forbidden c . This theorem invokes Bose symmetry and rotational invariance arguments. Nevertheless, as soon as this requirement is relaxed, the V V V vertex with the three bosons on-shell can exist. In particular, the rare decays of the Z gauge boson Z → γγ and Z → gg are allowed.In this paper, we are interested in studying the decays Z → γγ and Z → gg in the context of the minimal Lorentz-and CP T -violating Standard Model Extension 45,46 (SME), which is a renormalizable extension of the SM that incorporat...

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Section: -52mentioning

confidence: 99%

Section: -90mentioning

confidence: 99%

Section: -90mentioning

confidence: 99%

Section: Decay Z → γγmentioning

confidence: 99%

See 2 more Smart Citations

Decays Z → γγ and Z → gg in the Standard Model Extension

Castro-Medina

Novales‐Sánchez

Toscano

et al. 2015

Int. J. Mod. Phys. A

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“…The most general version of the SME contains renormalizable couplings and nonrenormalizable ones [6][7][8][9] as well, for no restriction from effective field theory to this respect exists. In the present paper, we consider the minimal SME, which is a subset of such general framework that includes only the Lorentz-violating terms that are renormalizable.…”

Section: Introductionmentioning

confidence: 99%

One-loop nonbirefringent effects on the electromagnetic vertex in the Standard Model Extension

Moyotl

Novales‐Sánchez

Toscano

et al. 2014

Int. J. Mod. Phys. A

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Lorentz violation emerged from a fundamental description of nature may impact, at low energies, the Maxwell sector, so that contributions from such new physics to the electromagnetic vertex would be induced. Particularly, nonbirefringent CP T -even effects from the electromagnetic sector modified by the Lorentz-and CP T -violating Standard Model Extension alter the structure of the free photon propagator. We calculate Lorentz-violating contributions to the electromagnetic vertex, at the one-loop level, by using a modified photon propagator carrying this sort of effects. We take the photon off shell, and find an expression that involves both isotropic and anisotropic effects of nonbirefringent violation of Lorentz invariance. Our analysis of the one-loop vertex function includes gauge invariance, transformation properties under C, P , and T , and tree-level contributions from Lorentz-violating nonrenormalizable interactions. These elements add to previous studies of the one-loop contributions to the electromagnetic vertex in the context of Lorentz violation in the photon sector. Finally, we restrict our analysis to the isotropic case and derive a finite contribution from isotropic Lorentz violation to the anomalous magnetic moment of fermions that coincides with the result already reported in the literature.

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Impact of Lorentz violation on anomalous magnetic moments of charged leptons

Crivellin

Kirk

Schreck

2022

J. High Energ. Phys.

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We address the question whether a violation of Lorentz symmetry can explain the tension between the measurement and the Standard-Model prediction of the anomalous magnetic moment of the muon, (g − 2)μ, and whether it can significantly impact the one of the electron, (g — 2)e. While anisotropic Lorentz-violating effects are, in general, expected to produce sidereal oscillations in observables, isotropic Lorentz violation (LV) in the charged-lepton sector could also feed into (g — 2)e,μ. However, we find that this type of Lorentz violation, parametrised via a dim-4 field operator of the Standard-Model Extension (SME), is already strongly constrained by the absence of vacuum Čerenkov radiation and photon decay. In particular, the observations of very-high-energetic astrophysical photons at LHAASO and of high-energetic electrons (muons) by the LHC (IceCube) place the most stringent two-sided bounds on the relevant SME coefficients $$ \overset{\circ }{c} $$ c ∘ (e) ($$ \overset{\circ }{c} $$ c ∘ (μ)). Therefore, any explanation of the tension in (g − 2)μ via isotropic Lorentz violation of the minimal spin-degenerate SME is excluded, and the possible size of its impact on (g − 2)e is very limited.

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Gauge invariant electromagnetic properties of fermions induced by CPT-violation in the Standard Model Extension

Cited by 26 publications

References 55 publications

Decays Z → γγ and Z → gg in the Standard Model Extension

Decays Z → γγ and Z → gg in the Standard Model Extension

One-loop nonbirefringent effects on the electromagnetic vertex in the Standard Model Extension

Impact of Lorentz violation on anomalous magnetic moments of charged leptons

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