Probing anomalous t t ¯ Z $$ t\overline{t}Z $$ interactions with rare meson decays

Abstract:We consider the three CP-conserving dimension-6 operators that encode the leading new-physics effects in the triple gauge couplings. The contributions to the standardmodel electromagnetic dipole and semi-leptonic vector and axial-vector interactions that arise from the insertions of these operators are calculated. We show that radiative and rare B-meson decays provide, under certain assumptions, constraints on two out of the three anomalous couplings that are competitive with the restrictions obtained from LEP II, Tevatron and LHC data. The constraints arising from the Z → bb electroweak pseudo observables, K → πνν and / are also studied.

“…Like in case of anomalous Ztt couplings, this finding illustrates the complementarity and synergy between indirect [25] and direct [26] searches for physics beyond the SM.…”

Section: Jhep09(2015)018supporting

confidence: 52%

Anomalous triple gauge couplings from B-meson and kaon observables

Bobeth

Haisch

2015

“…This virtue together with the lack of a clear evidence for direct production of new particles at the Large Hadron Collider (LHC) has prompted considerable theoretical and experimental activities that led to the development of the SMEFT framework and its consistent and systematic application to LHC data. Important steps in the theoretical development of SMEFT were the classification of all independent dimension-six SMEFT operators in [1] (see also [2] for related earlier work) and the calculation of the full one-loop anomalous dimension matrix of these operators in a series of papers [3][4][5][6] -partial one-loop and two-loop results have also been obtained in [7][8][9][10][11][12][13]. Considerable progress has also been made recently in improving the precision of matching calculations in perturbative extensions of the SM.…”

Section: Motivationmentioning

confidence: 99%

Singlet night in Feynman-ville: one-loop matching of a real scalar

Haisch

Ruhdorfer

Salvioni

et al. 2020

A complete one-loop matching calculation for real singlet scalar extensions of the Standard Model to the Standard Model effective field theory (SMEFT) of dimension-six operators is presented. We compare our analytic results obtained by using Feynman diagrams to the expressions derived in the literature by a combination of the universal one-loop effective action (UOLEA) approach and Feynman calculus. After identifying contributions that have been overlooked in the existing calculations, we find that the pure diagrammatic approach and the mixed method lead to identical results. We highlight some of the subtleties involved in computing one-loop matching corrections in SMEFT. arXiv:2003.05936v2 [hep-ph]

“…Hq, 33 and Q (1) Hq, 33 . The implications of constraints from rare meson decays for anomalous ttZ couplings in the limit of heavy quark masses have been treated in Ref.…”

Section: Vector-like Quarksmentioning

confidence: 99%

The Z penguin in generic extensions of the Standard Model

Brod

Gorbahn

2019

Self Cite

Precision flavour observables play an important role in the interpretation of results at the LHC in terms of models of new physics. We present the result for the oneloop Z penguin in generic extensions of the standard model which exhibit exact perturbative unitarity. We use Slavnov-Taylor identities to study the implications of unitarity on the renormalisation of the Z penguin, and derive a manifestly finite result that depends on a reduced set of of physical couplings.