If the weak were strong and the strong were weak

Lohitsiri, Nakarin; Tong, David

doi:10.21468/scipostphys.7.5.059

Cited by 12 publications

(18 citation statements)

References 74 publications

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“…It was shown in ref. [42] that theories in this family have the same phase structure as the Standard Model when one varies the relative strength between the strong force and the weak force. It is also not far-fetched to assume that this family of theories exhibits similar features in the infrared.…”

Section: A Generalisation Of the Smmentioning

confidence: 96%

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Global anomalies in the Standard Model(s) and beyond

Davighi

Gripaios

Lohitsiri

2020

J. High Energ. Phys.

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We analyse global anomalies and related constraints in the Standard Model (SM) and various Beyond the Standard Model (BSM) theories. We begin by considering four distinct, but equally valid, versions of the SM, in which the gauge group is taken to be G = G SM /Γ n , with G SM = SU(3) × SU(2) × U(1) and Γ n isomorphic to Z/n where n ∈ {1, 2, 3, 6}. In addition to deriving constraints on the hypercharges of fields transforming in arbitrary representations of the SU(3) × SU(2) factor, we study the possibility of global anomalies in theories with these gauge groups by computing the bordism groups Ω Spin 5 (BG) using the Atiyah-Hirzebruch spectral sequence. In two cases we show that there are no global anomalies beyond the Witten anomaly, while in the other cases we show that there are no global anomalies at all, illustrating the subtle interplay between local and global anomalies. While freedom from global anomalies has been previously shown for the specific fermion content of the SM by embedding the SM in an anomaly-free SU(5) GUT, our results here remain true when the SM fermion content is extended arbitrarily. Going beyond the SM gauge groups, we show that there are no new global anomalies in extensions of the (usual) SM gauge group by U(1) m for any integer m, which correspond to phenomenologically well-motivated BSM theories featuring multiple Z bosons. Nor do we find any new global anomalies in various grand unified theories, including Pati-Salam and trinification models. We also consider global anomalies in a family of theories with gauge group SU(N) × Sp(M) × U(1), which share the phase structure of the SM for certain (N, M). Lastly, we discuss a BSM theory in which the SM fermions are defined using a spin c structure, for example by gauging B − L. Such a theory may be extended to all orientable four-manifolds, and we find no global anomalies.

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Section: A Generalisation Of the Smmentioning

confidence: 96%

“…The Standard Model with gauge group G SM = SU(3) × SU(2) × U(1) is the starting point of a 2-parameter family of anomaly-free chiral gauge theories [41,42]. The gauge group for this family of generalised Standard Model theories is…”

Section: A Generalisation Of the Smmentioning

confidence: 99%

Global anomalies in the Standard Model(s) and beyond

Davighi

Gripaios

Lohitsiri

2020

J. High Energ. Phys.

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“…In this section we will analyse the chiral theories presented in [27]. These are certain SU (N ) × Sp(r) gauge theories that exhibit a similar behaviour to the theories studied in 7.1.…”

Section: Lohitsiri-tong Chiral Modelsmentioning

confidence: 99%

Anomalies for anomalous symmetries

Karasik

2021

Preprint

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4d gauge theories with massless fermions typically have axial U(1) transformations that suffer from the ABJ anomaly. One can modify the theory of interest by adding more fields in a way that restores the axial symmetry, and use it to derive rigorous 't-Hooft anomaly matching conditions. These conditions are not valid for the original theory of interest, but for the modified theory. We show that the modification can be done in a specific way that allows us to relate the dynamics of the modified theory to the dynamics of the original theory. In this way, the anomaly matching conditions of the modified theory can be used to learn new things on the original theory even though they involve axial transformations which are not a symmetry of the original theory. We describe this method and discuss some applications to various examples.

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“…The gauged, spontaneously broken U (1) subgroup also * Electronic address: B.C.Allanach@damtp.cam.ac.uk † Electronic address: gripaios@hep.phy.cam.ac.uk ‡ Electronic address: jss85@cam.ac.uk 1 An obvious, rare, exception is the SU (5) GUT. 2 It is well known that local anomalies place non-trivial constraints upon representations of chiral fermions. For example, in the SM, if we allow the hypercharges of the fermions to vary over the reals, the combination of gauge and gravitational anomaly cancellation implies that the charges must be commensurate [1].…”

Section: Introductionmentioning

confidence: 99%

“…For example, in the SM, if we allow the hypercharges of the fermions to vary over the reals, the combination of gauge and gravitational anomaly cancellation implies that the charges must be commensurate [1]. Conversely, if the hypercharges are commensurate but otherwise free, gauge anomaly cancellation of a family of SM chiral fermions implies gravitational anomaly cancellation [2] within that family. 3 The global part is somewhat tricky to study in such models, not least because we don't know (though some might say we don't care) what the gauge group is (see [3,4] for details).…”

Section: Introductionmentioning

confidence: 99%

Solving local anomaly equations in gauge-rank extensions of the standard model

2020

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We consider local (or perturbative) gauge anomalies in models which extend the rank of the Standard Model (SM) gauge group and the chiral fermion content only by n SM singlets. We give a general solution to the anomaly cancellation conditions (ACCs) of an additional U (1) subgroup for the ACCs that involve only SM fermions and we examine whether a corresponding solution exists for the remaining ACCs. We show that a solution to the remaining ACCs always exists for n ≥ 5 in the family non-universal case or n ≥ 3 in the family-universal case. In the special case where only a single family carries non-vanishing charges, we find a general solution to all ACCs, for any value of n.

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If the weak were strong and the strong were weak

Cited by 12 publications

References 74 publications

Global anomalies in the Standard Model(s) and beyond

Global anomalies in the Standard Model(s) and beyond

Anomalies for anomalous symmetries

Solving local anomaly equations in gauge-rank extensions of the standard model

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