Search for the anomalous ZZγ and Zγγ couplings via ννγ production at the CLIC

Spor, S.; Gürkanlı, E.; Köksal, M.

doi:10.1016/j.nuclphysb.2022.115785

Cited by 11 publications

(1 citation statement)

References 24 publications

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“…Furthermore, neutral gauge boson production via electron-positron collisions have received a significant experimental [21][22][23] and theoretical [24][25][26][27][28] interest, motivated by the search for anomalous neutral gauge boson self couplings. In particular, Z-pair events provide an opportunity for the investigation of possible triple neutral gauge boson couplings, ZZγ and ZZZ [29][30][31], not allowed at tree level in the SM.…”

Section: Introductionmentioning

confidence: 99%

Beam polarization effects on Z-boson pair production at electron-positron colliders: a full one-loop analysis

Demırci¹,

Balantekin²

2022

Preprint

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We present high-precision predictions for Z boson-pair production via electron-positron collisions by taking into account a full set of one-loop order scattering amplitudes, i.e., electroweak (EW) corrections together with soft and hard QED radiation. We provide a detailed numerical evaluation, from full EW corrections to pure QED corrections, specifically focusing on the effect of initial beam polarization on production rate. The left-right asymmetry and angular distributions are also presented. The radiative corrections are largely affected by initial beam polarizations. We get an improvement as around three times with completely polarized beams of e −L and e + R . We find that the radiative corrections can sizably modify the production rate, typically yielding a total relative correction up to a few tens of a percent. This imply that the full EW corrections are required for e − e + → ZZ to match with percent level accuracy.

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Section: Introductionmentioning

confidence: 99%

Beam polarization effects on Z-boson pair production at electron-positron colliders: a full one-loop analysis

Demırci¹,

Balantekin²

2022

Preprint

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Capping the positivity cone: dimension-8 Higgs operators in the SMEFT

Chen,

Mimasu,

et al. 2024

J. High Energ. Phys.

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SMEFT Wilson coefficients are subject to various positivity bounds in order to be consistent with the fundamental principles of S-matrix. Previous bounds on dimension-8 SMEFT operators have been obtained using the positivity part of UV partial wave unitarity and form a (projective) convex cone. We derive a set of linear UV unitarity conditions that go beyond positivity and are easy to implement in an optimization scheme with dispersion relations in a multi-field EFT. Using Higgs scattering as an example, we demonstrate how to obtain closed bounds in the space of the three relevant dimension-8 coefficients, making use of the UV unitarity conditions as well as so-called null constraints that arise from full crossing symmetry. Specifically, we show that they are bounded by inequalities schematically going like C <$$ \mathcal{O} $$ O ((4π)2). We compare the newly obtained upper bounds with the traditional perturbative unitarity bounds from within the EFT, and discuss some phenomenological implications of the two-sided positivity bounds in the context of experimental probes of Vector Boson Scattering.

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Dimension-8 SMEFT analysis of minimal scalar field extensions of the Standard Model

Ellis,

Mimasu,

Zampedri

2023

J. High Energ. Phys.

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We analyze the constraints obtainable from present data using the Standard Model Effective Field Theory (SMEFT) on extensions of the Standard Model with additional electroweak singlet or triplet scalar fields. We compare results obtained using only contributions that are linear in dimension-6 operator coefficients with those obtained including terms quadratic in these coefficients as well as contributions that are linear in dimension-8 operator coefficients. We also implement theoretical constraints arising from the stability of the electroweak vacuum and perturbative unitarity. Analyzing the models at the dimension-8 level constrains scalar couplings that are not bounded at the dimension-6 level. The strongest experimental constraints on the singlet model are provided by Higgs coupling measurements, whereas electroweak precision observables provide the strongest constraints on the triplet model. In the singlet model the present di-Higgs constraints already play a significant role. We find that the current constraints on model parameters are already competitive with those anticipated from future di- and tri-Higgs measurements. We compare our results with calculations in the full model, exhibiting the improvements when higher-order SMEFT terms are included. We also identify regions in parameter space where the SMEFT approximation appears to break down. We find that the combination of current constraints with the theoretical bounds still admits regions where the SMEFT approach is not valid, particularly for lower scalar boson masses.

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Search for the anomalous ZZγ and Zγγ couplings via ννγ production at the CLIC

Cited by 11 publications

References 24 publications

Beam polarization effects on Z-boson pair production at electron-positron colliders: a full one-loop analysis

Beam polarization effects on Z-boson pair production at electron-positron colliders: a full one-loop analysis

Capping the positivity cone: dimension-8 Higgs operators in the SMEFT

Dimension-8 SMEFT analysis of minimal scalar field extensions of the Standard Model

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