Search results for: Andrzej J. Buras

Items from 1 to 20 out of 95 results

article

Anatomy of $$\varepsilon '/\varepsilon $$ ε′/ε beyond the standard model

Jason Aebischer, Christoph Bobeth, Andrzej J. Buras, David M. Straub

The European Physical Journal C > 2019 > 79 > 3 > 1-28

We present for the first time a model-independent anatomy of the ratio $$\varepsilon '/\varepsilon $$ ε′/ε in the context of the $$\Delta S = 1$$ ΔS=1 effective theory with operators invariant under QCD and QED and in the context of the standard model effective field theory (SMEFT) with the operators invariant under the full SM gauge group. Our goal is to identify the new physics scenarios that...

article

Emerging $$\Delta M_{d}$$ ΔMd -anomaly from tree-level determinations of $$|V_{cb}|$$ |Vcb| and the angle $$\gamma $$ γ

Monika Blanke, Andrzej J. Buras

The European Physical Journal C > 2019 > 79 > 2 > 1-8

We point out that the recently increased value of the angle $$\gamma $$ γ in the unitarity triangle (UT), determined in tree-level decays to be $$\gamma =(74.0^{+5.0}_{-5.8})^\circ $$ γ=(74.0-5.8+5.0)∘ by the LHCb collaboration, combined with the most recent value of $$|V_{cb}|$$ |Vcb| implies an enhancement of $$\Delta M_{d}$$ ΔMd over the data in the ballpark of $$30\%$$ 30% . This is larger...

article

BSM hadronic matrix elements for ε^′/ε and K → ππ decays in the Dual QCD approach

Jason Aebischer, Andrzej J. Buras, Jean-Marc Gérard

Journal of High Energy Physics > 2019 > 2019 > 2 > 1-37

Abstract We calculate for the first time all four-quark hadronic matrix elements of local operators possibly contributing to K → ππ decays and in particular to the ratio ε^′/ε beyond the Standard Model (BSM). To this end we use the Dual QCD (DQCD) approach. In addition to 7 new mirror operators obtained from the SM ones by flipping the chirality, we count 13 BSM four-quark operators of a given chirality...

article

K → ππ and K − π matrix elements of the chromomagnetic operators from Dual QCD

Andrzej J. Buras, Jean-Marc Gérard

Journal of High Energy Physics > 2018 > 2018 > 7 > 1-16

Abstract We perform for the first time a direct calculation of on-shell K → ππ hadronic matrix elements of chromomagnetic operators (CMO) in the Standard Model and beyond. To this end, we use the successful Dual QCD (DQCD) approach in which we also consider off-shell K − π matrix elements that allow the comparison with lattice QCD calculations presented recently by the ETM collaboration. Working...

article

Analytic inclusion of the scale dependence of the anomalous dimension matrix in Standard Model Effective Theory

Andrzej J. Buras, Martin Jung

Journal of High Energy Physics > 2018 > 2018 > 6 > 1-19

Abstract The renormalization group equations (RGEs) in Standard Model effective theory are usually either solved analytically, neglecting the scale dependence of gauge and Yukawa couplings, or numerically without such approximations. We present analytic solutions of RGEs that take into account the dominant scale dependence of the anomalous-dimension matrix due to the running of the QCD coupling α...

article

Leptoquarks meet ε^′/ε and rare Kaon processes

Christoph Bobeth, Andrzej J. Buras

Journal of High Energy Physics > 2018 > 2018 > 2 > 1-52

Abstract We analyse for the first time the CP violating ratio ε^′/ε in K → ππ decays in leptoquark (LQ) models. Assuming a mass gap to the electroweak (EW) scale, the main mechanism for LQs to contribute to ε^′/ε is EW gauge-mixing of semi-leptonic into non-leptonic operators, which we treat in the Standard Model effective theory (SMEFT). We perform also the one-loop decoupling for scalar LQs, finding...

article

Yukawa enhancement of Z-mediated new physics in ∆S = 2 and ∆B = 2 processes

Christoph Bobeth, Andrzej J. Buras, Alejandro Celis, Martin Jung

Journal of High Energy Physics > 2017 > 2017 > 7 > 1-39

Abstract We discuss Yukawa-enhanced contributions from Z-mediated new physics to down-type quark ΔF = 2 processes in the framework of the standard model gauge-invariant effective theory (SMEFT). Besides the renormalization group (RG) mixing of the Z-mediating ψ²H²D operators into ΔF = 2 operators, we include at the electroweak scale one-loop (NLO) matching corrections consistently, necessary for...

article

Patterns of flavour violation in models with vector-like quarks

Christoph Bobeth, Andrzej J. Buras, Alejandro Celis, Martin Jung

Journal of High Energy Physics > 2017 > 2017 > 4 > 1-72

Abstract We study the patterns of flavour violation in renormalisable extensions of the Standard Model (SM) that contain vector-like quarks (VLQs) in a single complex representation of either the SM gauge group G_SM or G _SM^′ ≡ G_SM ⊗ U(1)L_μ − L_τ^. We first decouple VLQs in the M = (1 − 10) TeV range and then at the electroweak scale also Z, Z^′ gauge bosons and additional scalars to study the phenomenology...

article

Final state interactions in $$K\rightarrow \pi \pi $$ K → π π decays: $$\Delta I=1/2$$ Δ I = 1 / 2 rule vs. $$\varepsilon '/\varepsilon $$ ε ′ / ε

Andrzej J. Buras, Jean-Marc Gérard

The European Physical Journal C > 2017 > 77 > 1 > 1-6

Dispersive effects from strong $$\pi \pi $$ π π rescattering in the final state interaction (FSI) of weak $$K\rightarrow \pi \pi $$ K → π π decays are revisited with the goal to have a global view on their relative importance for the $$\Delta I=1/2$$ Δ I = 1 / 2 rule and the ratio $$\varepsilon '/\varepsilon $$ ε ′ / ε in the standard model (SM). We point...

article

331 Models Facing the Tensions in ΔF = 2 Processes with the Impact on ε^′/ε, B_s → μ⁺μ⁻ and B →K^∗μ⁺μ⁻

Andrzej J. Buras, Fulvia Fazio

Journal of High Energy Physics > 2016 > 2016 > 8 > 1-28

Abstract Motivated by the recently improved results from the Fermilab Lattice and MILC Collaborations on the hadronic matrix elements entering ΔM_s,d in B s , d 0 − B ¯ s , d 0 $$ {B}_{s,d}^0-{\overline{B}}_{s,d}^0 $$ mixings and the resulting increased tensions between ΔM_s,d and ε_K in the Standard Model (SM) and CMFV models, we demonstrate that these tensions can be removed in...

chapter

CP Violation in B and K Decays: 2003

Andrzej J. Buras

Lecture Notes in Physics > Lectures on Flavor Physics > 85-135

CP violation in B and K meson decays is not surprisingly one of the central topics in particle physics. Indeed, CP-violating and rare decays of K and B mesons are very sensitive to the flavour structure of the Standard Model (SM) and its extensions. In this context a very important role is played by the Cabibbo-Kobayashi-Maskawa (CKM) matrix [1,2] that parametrizes the weak charged current interactions...

chapter

Operator Product Expansion, Renormalization Group and Weak Decays

Andrzej J. Buras

Lecture Notes in Physics > Quantum Field Theory > Talks > 65-85

A non-technical description of the Operator Product Expansion and Renormalization Group techniques as applied to weak decays of mesons is presented. We use this opportunity to summarize briefly the present status of the next-to-leading QCD corrections to weak decays and their implications for the unitarity triangle, the ratio έ/ε; the radiative decay B → X _sγ, and the rare decays $$ K^ +...

chapter

CP Violation in B and K Decays: 2003

Andrzej J. Buras

Lecture Notes in Physics > Lectures on Flavor Physics > 85-135

chapter

Waiting for Clear Signals of New Physics in B and K Decays

Andrzej J. Buras

Springer Proceedings in Physics > Particle Physics and the Universe > Standard Model — Theory and Experiment > 315-331

article

Flavour physics: Status and perspectives

Andrzej J. Buras

Annalen der Physik > 528 > 1-2 > 96 - 101

The pattern of quark flavour violation predicted by the Standard Model agrees within theoretical and experimental uncertainties with the available data except for a number of intriguing anomalies that require further investigation. In the coming flavour precision era a multitude of new observables will be measured and the accuracy of the measurements of quark flavour violating rare processes and of...

article

ε ^′ /ε in 331 models

Andrzej J. Buras, Fulvia Fazio

Journal of High Energy Physics > 2016 > 2016 > 3 > 1-24

Abstract Motivated by the recent findings that the ratio ε ^′ /ε in the Standard Model (SM) appears to be significantly below the data we investigate whether the necessary enhancement of ε ^′ /ε can be obtained in 331 models, based on the gauge group SU(3)_C × SU(3)_L...

article

Universal Unitarity Triangle 2016 and the tension between $$\Delta M_{s,d}$$ Δ M s , d and $$\varepsilon _K$$ ε K in CMFV models

Monika Blanke, Andrzej J. Buras

The European Physical Journal C > 2016 > 76 > 4 > 1-12

Motivated by the recently improved results from the Fermilab Lattice and MILC Collaborations on the hadronic matrix elements entering $$\Delta M_{s,d}$$ Δ M s , d in $$B_{s,d}^0$$ B s , d 0 – $$\bar{B}_{s,d}^0$$ B ¯ s , d 0 mixing, we determine the universal unitarity triangle (UUT) in models with constrained minimal flavour violation (CMFV). Of particular...

article

Quark flavour observables in the Littlest Higgs model with T-parity after LHC Run 1

Monika Blanke, Andrzej J. Buras, Stefan Recksiegel

The European Physical Journal C > 2016 > 76 > 4 > 1-20

The Littlest Higgs model with T-parity (LHT) belongs to the simplest new physics scenarios with new sources of flavour and CP violation. The latter originate in the interactions of ordinary quarks and leptons with heavy mirror quarks and leptons that are mediated by new heavy gauge bosons. Also a heavy fermionic top partner is present in this model which communicates with the SM fermions by means...

article

New physics patterns in ε′/ε and ε _K with implications for rare kaon decays and ∆M _K

Andrzej J. Buras

Journal of High Energy Physics > 2016 > 2016 > 4 > 1-66

Abstract The Standard Model (SM) prediction for the ratio ε′/ε appears to be significantly below the experimental data. Also ε _K in the SM tends to be below the data. Any new physics (NP) removing these anomalies will first of all have impact on flavour observables in the K meson system, in particular on rare decays K + → π + ν ν ¯ $$ {K}^{+}\to {\pi}^{+}\nu...

article

Upper bounds on ε′/ε parameters B₆^(1/2) and B₈^(3/2) from large N QCD and other news

Andrzej J. Buras, Jean-Marc Gérard

Journal of High Energy Physics > 2015 > 2015 > 12 > 1-20

Abstract We demonstrate that in the large N approach developed by the authors in collaboration with Bardeen, the parameters B₆^(1/2) and B₈^(3/2) parametrizing the K → ππ matrix elements 〈Q₆〉₀ and 〈Q₈〉₂ of the dominant QCD and electroweak operators receive both negative O 1 / N $$ \mathcal{O}\left(1/N\right) $$ corrections such that B₆^(1/2) ≤ B₈^(3/2) < 1 in agreement with the recent...

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Search results for: Andrzej J. Buras

Anatomy of $$\varepsilon '/\varepsilon $$ ε′/ε beyond the standard model

Emerging $$\Delta M_{d}$$ ΔMd -anomaly from tree-level determinations of $$|V_{cb}|$$ |Vcb| and the angle $$\gamma $$ γ

BSM hadronic matrix elements for ε^′/ε and K → ππ decays in the Dual QCD approach

K → ππ and K − π matrix elements of the chromomagnetic operators from Dual QCD

Analytic inclusion of the scale dependence of the anomalous dimension matrix in Standard Model Effective Theory

Leptoquarks meet ε^′/ε and rare Kaon processes

Yukawa enhancement of Z-mediated new physics in ∆S = 2 and ∆B = 2 processes

Patterns of flavour violation in models with vector-like quarks

Final state interactions in $$K\rightarrow \pi \pi $$ K → π π decays: $$\Delta I=1/2$$ Δ I = 1 / 2 rule vs. $$\varepsilon '/\varepsilon $$ ε ′ / ε

331 Models Facing the Tensions in ΔF = 2 Processes with the Impact on ε^′/ε, B_s → μ⁺μ⁻ and B →K^∗μ⁺μ⁻

CP Violation in B and K Decays: 2003

Operator Product Expansion, Renormalization Group and Weak Decays

CP Violation in B and K Decays: 2003

Waiting for Clear Signals of New Physics in B and K Decays

Flavour physics: Status and perspectives

ε ^′ /ε in 331 models

Universal Unitarity Triangle 2016 and the tension between $$\Delta M_{s,d}$$ Δ M s , d and $$\varepsilon _K$$ ε K in CMFV models

Quark flavour observables in the Littlest Higgs model with T-parity after LHC Run 1

New physics patterns in ε′/ε and ε _K with implications for rare kaon decays and ∆M _K

Upper bounds on ε′/ε parameters B₆^(1/2) and B₈^(3/2) from large N QCD and other news

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