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Buras, Andrzej J.; Uhlig, Selma; Schwab, Félix

doi:10.1103/revmodphys.80.965

Cited by 105 publications

(116 citation statements)

References 229 publications

(271 reference statements)

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“…For K + → π + ν iνi [36][37][38][39][40] where λ K (q 2 ) is a phase space factor, f + and f T are q 2 -dependent form factors. The B → πµ + µ − rate is obtained with obvious replacements.…”

Section: Jhep10(2015)027mentioning

confidence: 99%

New vector-like fermions and flavor physics

Ishiwata

Ligeti

Wise

2015

J. High Energ. Phys.

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Abstract:We study renormalizable extensions of the standard model that contain vectorlike fermions in a (single) complex representation of the standard model gauge group. There are 11 models where the vector-like fermions Yukawa couple to the standard model fermions via the Higgs field. These models do not introduce additional fine-tunings. They can lead to, and are constrained by, a number of different flavor-changing processes involving leptons and quarks, as well as direct searches. An interesting feature of the models with strongly interacting vector-like fermions is that constraints from neutral meson mixings (apart from CP violation in K 0 −K 0 mixing) are not sensitive to higher scales than other flavor-changing neutral-current processes. We identify order 1/(4πM ) 2 (where M is the vector-like fermion mass) one-loop contributions to the coefficients of the four-quark operators for meson mixing, that are not suppressed by standard model quark masses and/or mixing angles.

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Section: Jhep10(2015)027mentioning

confidence: 99%

New vector-like fermions and flavor physics

Ishiwata

Ligeti

Wise

2015

J. High Energ. Phys.

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“…Unfortunately, whereas the branching ratios of K → πνν decays are theoretically very clean [15] and those of K L → π 0 ℓ + ℓ − are subject to only moderate theoretical uncertainties [16], this is not the case for the ratio ε ′ /ε that is affected by large hadronic uncertainties. Indeed, whereas the Wilson coefficients of the local operators entering the evaluation of ε ′ /ε are known [17][18][19][20][21][22] at the NLO level in QCD and QED renormalization group improved perturbation theory, the hadronic matrix elements of these operators are still only poorly known.…”

Section: Introductionmentioning

confidence: 99%

Correlations between ε′/ε and rareKdecays in the Littlest Higgs model with T-parity

Blanke¹,

Buras²,

Recksiegel³

et al. 2007

J. High Energy Phys.

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We calculate the CP-violating ratio ε ′ /ε in the Littlest Higgs model with T-parity (LHT) and investigate its correlations with the branching ratios for K L → π 0 νν, K L → π 0 ℓ + ℓ − and K + → π + νν. The resulting correlations are rather strong in the case of K L decays, but less pronounced in the case of K + → π + νν. Unfortunately, they are subject to large hadronic uncertainties present in ε ′ /ε, whose theoretical prediction in the Standard Model (SM) is reviewed and updated here. With the matrix elements of Q 6 (gluon penguin) and Q 8 (electroweak penguin) evaluated in the large-N limit and m MS s (2 GeV) = 100 MeV from lattice QCD, (ε ′ /ε) SM turns out to be close to the data so that significant departures of Br(K L → π 0 νν) and Br(K L → π 0 ℓ + ℓ − ) from the SM expectations are unlikely, while Br(K + → π + νν) can be enhanced even by a factor 5. On the other hand, modest departures of the relevant hadronic matrix elements from their large-N values allow for a consistent description of ε ′ /ε within the LHT model accompanied by large enhancements of Br(K L → π 0 νν) and Br(K L → π 0 ℓ + ℓ − ), but only modest enhancements of Br(K + → π + νν). Note addedAn additional contribution to the Z penguin in the Littlest Higgs model with T-parity has been pointed out in [1,2], which has been overlooked in the present analysis. This contribution leads to the cancellation of the left-over quadratic divergence in the calculation of some rare decay amplitudes. Instead of presenting separate errata to the present work and our papers [3][4][5][6] partially affected by this omission, we have presented a corrected and updated analysis of flavour changing neutral current processes in the Littlest Higgs model with T-parity in [7].

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“…The decay K ± → π ± νν is very sensitive to New Physics models where the theoretical predictions vary over an order of magnitude. Thus measuring Br(K + → π + νν) could help to distinguish between the different types of New Physics [15] once it is discovered at the collider experiments.…”

Section: Measurement Ofmentioning

confidence: 99%

Rare Kaon Decays at CERN SPS

Kozhuharov¹,

Collaborations²

2010

AIP Conference Proceedings

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Abstract.Since their discovery the K-mesons continue to provide valuable information to the theory of the interactions between the elementary particles. In two years of data taking the NA48/2 experiment at CERN SPS recorded more than 4 billion K ± → π + π − π ± decays devoted to the search of CP violation in the charged kaon system. The huge statistics allows also a precise study of rare kaon decays. The results from the investigation of K ± → π ± e + e − decay will be shown with their interpretation within several theoretical models. The continuation of the kaon program at CERN is the NA62 experiment devoted to the measurement of Br(K ± → π ± νν) decay with a precision of 10% in two years of data taking. The planned detector setup and the expected background and signal events will be presented. During 2007 a dedicated run devoted to NA62 prototype tests and study of K e2 decays was taken. The preliminary results from the study of Ke2 decays and the ratio R K = Γ(K ± → e ± ν)/Γ(K ± → μ ± ν) at the NA48/2 and NA62 experiments will be shown.

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Waiting for precise measurements ofK+→π+νν¯andKL

Cited by 105 publications

References 229 publications

New vector-like fermions and flavor physics

New vector-like fermions and flavor physics

Correlations between ε′/ε and rareKdecays in the Littlest Higgs model with T-parity

Rare Kaon Decays at CERN SPS

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