Natural Suppression of FCNCs at the One-Loop Level in $Z^\prime$ Models with Implications for K, D and B Decays

Buras, Andrzej J.

doi:10.48550/arxiv.2302.03051

Cited by 2 publications

(9 citation statements)

References 39 publications

(91 reference statements)

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“…In Section 2 we introduce the Z -Tandem in question and derive conditions on the couplings and masses of these two Z gauge bosons which allow us to achieve our goal. In this context the mixing matrix for Z interactions with quarks, presented recently by us [15], turns out to be crucial. In Section 3 the impact of this tandem on selected rare K and B meson decays is discussed leaving a detailed numerical analysis for the future.…”

Section: Introductionmentioning

confidence: 92%

“…it is evident that the difference between the phases φ ij 1 and φ ij 2 by 90 • assures the cancellation of these two contributions to M ij 12 . However, as demonstrated in [15], each of these matrices depends on only two mixing angles and two phases and it is not possible with two Z gauge bosons to remove NP from all ∆F = 2 observables, but fortunately this can be done for the ones in (1).…”

Section: Z -Tandemmentioning

confidence: 99%

“…It is evident from these matrices that once the bs and bd couplings are determined, the coupling sd is also determined as discussed in [15], a property known also from 331 models [16]. One finds then that once the second relation in ( 4) is used for the phases bs and bd, there is no difference between the sd phases of Z 1 and Z 2 gauge bosons so that in this case there is no cancellation of their contributions to ∆S = 2 observables like ε K .…”

Section: Z -Tandemmentioning

confidence: 99%

“…• NP parameters describing Z 1,2 interactions with quarks and present in the hermitian and unitary mixing matrices proposed recently [15], are determined exclusively from ∆F = 1 observables. Simultaneously the two Z gauge bosons collaborate in the explanation of the existing anomalies in ∆F = 1 decays.…”

Section: Introductionmentioning

confidence: 99%

“…Simultaneously the two Z gauge bosons collaborate in the explanation of the existing anomalies in ∆F = 1 decays. Due to a very strong suppression of their contributions to all FCNC observables at the one-loop level [15], the main arena for the Z -Tandem are ∆F = 1 decays with their tree-level contributions only, simplifying thereby the phenomenology.…”

Section: Introductionmentioning

confidence: 99%

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$Z^\prime$-Tandem Mechanism for the Suppression of New Physics in Quark Mixing with Implications for K, D and B Decays

Buras¹

2023

Preprint

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Z models belong to the ones that can most easily explain the anomalies in b → sµ + µ − transitions. However, such an explanation by a single Z gauge boson, as done in the literature, is severly constrained by the B 0 s − B0 s mixing. Also the recent finding, that the mass differences ∆M s , ∆M d , the CP-violating parameter ε K , and the mixing induced CP-asymmetries S ψK S and S ψφ can be simultaneously well described within the SM without new physics (NP) contributions, is a challenge for Z models with a single Z contributing at tree-level to quark mixing. We point out that including a second Z in the model allows to eliminate simultaneously tree-level contributions to the five ∆F = 2 observables used in the determination of the CKM parameters while leaving the room for NP in ∆M K and ∆M D . The latter one can be removed at the price of infecting ∆M s or ∆M d by NP which is presently disfavoured. This pattern is transparently seen using the new mixing matrix for Z interactions with quarks. This strategy allows significant tree-level contributions to K, B s and B d decays thereby allowing to explain the existing anomalies in b → sµ + µ − transitions and the anticipated anomaly in the ratio ε /ε much easier than in Z -Single scenarios. The proposed Z -Tandem mechanism bears some similarities to the GIM mechanism for the suppression of the FCNCs in the SM with the role of the charm quark played here by the second Z . However, it differs from the latter profoundly in that only NP contributions to quark mixing are eliminated at tree-level. We discuss briefly the implied flavour patterns in K and B decay observables in this NP scenario.

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Section: Introductionmentioning

confidence: 92%

Section: Z -Tandemmentioning

confidence: 99%

Section: Z -Tandemmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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$Z^\prime$-Tandem Mechanism for the Suppression of New Physics in Quark Mixing with Implications for K, D and B Decays

Buras¹

2023

Preprint

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Flavor changing neutral current processes and family discrimination in 3-3-1 models

Oliveira,

de S Pires

2023

J. Phys. G: Nucl. Part. Phys.

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In 3-3-1 models anomaly cancellation requires that one of the three families of quarks transforms as triplet by SU(3)L with the other two transforming necessarily as anti-triplet. This is an important feature of the model because with it we explain family replication. It is mandatory to discriminate which of the families will transform as triplet by SU(3)L because the main consequence of anomaly cancellation in 3-3-1 models is the arising of processes violating flavor at tree level by means of neutral currents mediated by gauge and scalar fields and each case leads to different results. In this work we consider the 3-3-1 model with right-handed neutrinos. Among the spectrum of 3-3-1 particles that contributes to the flavor changing neutral processes, there is a pseudoscalar that may be the lightest of the 3-3-1 particles and then should give the main contribution to such processes. We then calculate its contribution to the K0 - \bar K0 mixing transition and confront it with the current experimental results. We do this for the three cases in which one of the family of quarks transforms as a triplet by SU(3)L. According to our findings each case leads to different constraints on the mass of the pseudoscalar and the case in which the third family of quarks transforms as triplet seems to be the favoured one. We also obtain the most stringent bounds on the mass of the pseudoscalar of the model.

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Natural Suppression of FCNCs at the One-Loop Level in $Z^\prime$ Models with Implications for K, D and B Decays

Cited by 2 publications

References 39 publications

$Z^\prime$-Tandem Mechanism for the Suppression of New Physics in Quark Mixing with Implications for K, D and B Decays

$Z^\prime$-Tandem Mechanism for the Suppression of New Physics in Quark Mixing with Implications for K, D and B Decays

Flavor changing neutral current processes and family discrimination in 3-3-1 models

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