scholarly journals EXTENDED ANALYSIS OF THE “PENGUIN” PART OF THE K→ππ AMPLITUDE

1995 ◽  
Vol 10 (28) ◽  
pp. 4065-4086 ◽  
Author(s):  
A.A. PENIN ◽  
A.A. PIVOVAROV
Keyword(s):  
Theoretical Description ◽  
Effective Theory ◽  
Interaction Matrix ◽  
Matrix Elements ◽  
Kaon Decays ◽  
Penguin Contribution ◽  
The Standard Model ◽  
Penguin Operator ◽  
Extended Analysis

We make an attempt to clarify the role of the annihilation or “penguin” mode in the description of the K→ππ decay within the Standard Model. Attention is centered on new operators in the effective ΔS=1 Hamiltonian and the violation of factorization for mesonic matrix elements of the local four-quark operators. We propose a regular method to evaluate the mesonic matrix elements of K→ππ transitions based on the study of three-point correlators via QCD sum rules using the chiral effective theory as an underlying low energy model for strong interaction. Matrix elements of the QCD penguin operator are calculated within this approach. The total “penguin” contribution is found to be relatively large, which improves the theoretical description of the ΔI=1/2 rule in nonleptonic kaon decays.

scholarly journals SU(3) analysis of four-quark operators: K → ππ and vacuum matrix elements

2021 ◽  
Vol 2021 (6) ◽  
Author(s):  
A. Pich ◽  
A. Rodríguez-Sánchez
Keyword(s):  
Dispersion Relations ◽  
Matrix Elements ◽  
Lattice Data ◽  
Kaon Decays ◽  
Spectral Functions ◽  
Penguin Contribution ◽  
Electroweak Penguin ◽  
Dynamical Parameters ◽  
Analytical Approaches ◽  
Dynamical Origin

Abstract Hadronic matrix elements of local four-quark operators play a central role in non-leptonic kaon decays, while vacuum matrix elements involving the same kind of operators appear in inclusive dispersion relations, such as those relevant in τ-decay analyses. Using an SU(3)L ⊗ SU(3)R decomposition of the operators, we derive generic relations between these matrix elements, extending well-known results that link observables in the two different sectors. Two relevant phenomenological applications are presented. First, we determine the electroweak-penguin contribution to the kaon CP-violating ratio ε′/ε, using the measured hadronic spectral functions in τ decay. Second, we fit our SU(3) dynamical parameters to the most recent lattice data on K → ππ matrix elements. The comparison of this numerical fit with results from previous analytical approaches provides an interesting anatomy of the ∆I = $$ \frac{1}{2} $$ 1 2 enhancement, confirming old suggestions about its underlying dynamical origin.

scholarly journals BSM master formula for ε′/ε in the WET basis at NLO in QCD

2021 ◽  
Vol 2021 (12) ◽  
Author(s):  
Jason Aebischer ◽  
Christoph Bobeth ◽  
Andrzej J. Buras ◽  
Jacky Kumar
Keyword(s):  
Effective Field ◽  
Effective Theory ◽  
Tree Level ◽  
Matrix Elements ◽  
Electroweak Scale ◽  
The Standard Model ◽  
Quark Flavour ◽  
The Common ◽  
Qcd Analysis ◽  
First Time

Abstract As an important step towards a complete next-to-leading (NLO) QCD analysis of the ratio ε′/ε within the Standard Model Effective Field Theory (SMEFT), we present for the first time the NLO master formula for the BSM part of this ratio expressed in terms of the Wilson coefficients of all contributing operators evaluated at the electroweak scale. To this end we use the common Weak Effective Theory (WET) basis (the so-called JMS basis) for which tree-level and one-loop matching to the SMEFT are already known. The relevant hadronic matrix elements of BSM operators at the electroweak scale are taken from Dual QCD approach and the SM ones from lattice QCD. It includes the renormalization group evolution and quark-flavour threshold effects at NLO in QCD from hadronic scales, at which these matrix elements have been calculated, to the electroweak scale.

scholarly journals Role of Bc+→Bs,d(*)ℓ¯νℓ in the Standard Model and in the search for BSM signals

2021 ◽  
Vol 103 (7) ◽  
Author(s):  
Pietro Colangelo ◽  
Fulvia De Fazio ◽  
Francesco Loparco
Keyword(s):  
Standard Model ◽  
The Standard Model

scholarly journals Searching for charged lepton flavor violation at ep colliders

2021 ◽  
Vol 2021 (3) ◽  
Author(s):  
Stefan Antusch ◽  
A. Hammad ◽  
Ahmed Rashed
Keyword(s):  
Standard Model ◽  
Charged Lepton ◽  
Neutral Current ◽  
Effective Theory ◽  
Theory Approach ◽  
Lepton Flavor Violation ◽  
Lepton Flavor ◽  
Flavor Violation ◽  
The Standard Model ◽  
Order Of Magnitude

Abstract We investigate the sensitivity of electron-proton (ep) colliders for charged lepton flavor violation (cLFV) in an effective theory approach, considering a general effective Lagrangian for the conversion of an electron into a muon or a tau via the effective coupling to a neutral gauge boson or a neutral scalar field. For the photon, the Z boson and the Higgs particle of the Standard Model, we present the sensitivities of the LHeC for the coefficients of the effective operators, calculated from an analysis at the reconstructed level. As an example model where such flavor changing neutral current (FCNC) operators are generated at loop level, we consider the extension of the Standard Model by sterile neutrinos. We show that the LHeC could already probe the LFV conversion of an electron into a muon beyond the current experimental bounds, and could reach more than an order of magnitude higher sensitivity than the present limits for LFV conversion of an electron into a tau. We discuss that the high sensitivities are possible because the converted charged lepton is dominantly emitted in the backward direction, enabling an efficient separation of the signal from the background.

scholarly journals GWENA: gene co-expression networks analysis and extended modules characterization in a single Bioconductor package

2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Gwenaëlle G. Lemoine ◽  
Marie-Pier Scott-Boyer ◽  
Bathilde Ambroise ◽  
Olivier Périn ◽  
Arnaud Droit
Keyword(s):  
Muscle Development ◽  
R Package ◽  
Topological Information ◽  
Old Patients ◽  
Network Modules ◽  
Extended Analysis ◽  
Networks Analysis ◽  
Underlying Processes

Abstract Background Network-based analysis of gene expression through co-expression networks can be used to investigate modular relationships occurring between genes performing different biological functions. An extended description of each of the network modules is therefore a critical step to understand the underlying processes contributing to a disease or a phenotype. Biological integration, topology study and conditions comparison (e.g. wild vs mutant) are the main methods to do so, but to date no tool combines them all into a single pipeline. Results Here we present GWENA, a new R package that integrates gene co-expression network construction and whole characterization of the detected modules through gene set enrichment, phenotypic association, hub genes detection, topological metric computation, and differential co-expression. To demonstrate its performance, we applied GWENA on two skeletal muscle datasets from young and old patients of GTEx study. Remarkably, we prioritized a gene whose involvement was unknown in the muscle development and growth. Moreover, new insights on the variations in patterns of co-expression were identified. The known phenomena of connectivity loss associated with aging was found coupled to a global reorganization of the relationships leading to expression of known aging related functions. Conclusion GWENA is an R package available through Bioconductor (https://bioconductor.org/packages/release/bioc/html/GWENA.html) that has been developed to perform extended analysis of gene co-expression networks. Thanks to biological and topological information as well as differential co-expression, the package helps to dissect the role of genes relationships in diseases conditions or targeted phenotypes. GWENA goes beyond existing packages that perform co-expression analysis by including new tools to fully characterize modules, such as differential co-expression, additional enrichment databases, and network visualization.

scholarly journals Flavour Anomalies in a U(1) SUSY Extension of the SM

Symmetry ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 191
Author(s):  
Alexander Bednyakov ◽  
Alfiia Mukhaeva
Keyword(s):  
Standard Model ◽  
Parameter Space ◽  
Gauge Boson ◽  
New Physics ◽  
Low Energy ◽  
Effective Theory ◽  
The Standard Model ◽  
Meson Mixing ◽  
Additional Anomaly ◽  
Lepton Flavour

Flavour anomalies have attracted a lot of attention over recent years as they provide unique hints for possible New Physics. Here, we consider a supersymmetric (SUSY) extension of the Standard Model (SM) with an additional anomaly-free gauge U(1) group. The key feature of our model is the particular choice of non-universal charges to the gauge boson Z′, which not only allows a relaxation of the flavour discrepancies but, contrary to previous studies, can reproduce the SM mixing matrices both in the quark and lepton sectors. We pay special attention to the latter and explicitly enumerate all parameters relevant for our calculation in the low-energy effective theory. We find regions in the parameter space that satisfy experimental constraints on meson mixing and LHC Z′ searches and can alleviate the flavour anomalies. In addition, we also discuss the predictions for lepton-flavour violating decays B+→K+μτ and B+→K+eτ.

scholarly journals Another SMEFT story: Z′ facing new results on ε′/ε, ∆MK and K → $$ \pi \nu \overline{\nu} $$

2020 ◽  
Vol 2020 (12) ◽  
Author(s):  
Jason Aebischer ◽  
Andrzej J. Buras ◽  
Jacky Kumar
Keyword(s):  
Renormalization Group ◽  
Mass Difference ◽  
Branching Ratios ◽  
New Physics ◽  
Matrix Elements ◽  
Isospin Breaking ◽  
Left Handed ◽  
The Standard Model ◽  
First Time ◽  
Group Effects

Abstract Recently the RBC-UKQCD lattice QCD collaboration presented new results for the hadronic matrix elements relevant for the ratio ε′/ε in the Standard Model (SM) albeit with significant uncertainties. With the present knowledge of the Wilson coefficients and isospin breaking effects there is still a sizable room left for new physics (NP) contributions to ε′/ε which could both enhance or suppress this ratio to agree with the data. The new SM value for the K0 − $$ {\overline{K}}^0 $$ K ¯ 0 mass difference ∆MK from RBC-UKQCD is on the other hand by 2σ above the data hinting for NP required to suppress ∆MK. Simultaneously the most recent results for K+ → $$ {\pi}^{+}\nu \overline{\nu} $$ π + ν ν ¯ from NA62 and for KL → $$ {\pi}^0\nu \overline{\nu} $$ π 0 ν ν ¯ from KOTO still allow for significant NP contributions. We point out that the suppression of ∆MK by NP requires the presence of new CP-violating phases with interesting implications for K → $$ \pi \nu \overline{\nu} $$ πν ν ¯ , KS → μ+μ− and KL → π0ℓ+ℓ− decays. Considering a Z′-scenario within the SMEFT we analyze the dependence of all these observables on the size of NP still allowed by the data on ε′/ε. The hinted ∆MK anomaly together with the εK constraint implies in the presence of only left-handed (LH) or right-handed (RH) flavour-violating Z′ couplings strict correlation between K+ → $$ {\pi}^{+}\nu \overline{\nu} $$ π + ν ν ¯ and KL → $$ {\pi}^0\nu \overline{\nu} $$ π 0 ν ν ¯ branching ratios so that they are either simultaneously enhanced or suppressed relative to SM predictions. An anticorrelation can only be obtained in the presence of both LH and RH couplings. Interestingly, the NP QCD penguin scenario for ε′/ε is excluded by SMEFT renormalization group effects in εK so that NP effects in ε′/ε are governed by electroweak penguins. We also investigate for the first time whether the presence of a heavy Z′ with flavour violating couplings could generate through top Yukawa renormalization group effects FCNCs mediated by the SM Z-boson. The outcome turns out to be very interesting.

scholarly journals Direct CP violation and the ΔI = 1/2 rule in K → ππ decay in the Standard Model

2022 ◽  
Vol 258 ◽  
pp. 01003
Author(s):  
Christopher Kelly
Keyword(s):  
Cp Violation ◽  
Standard Model ◽  
Systematic Error ◽  
Error Estimates ◽  
Lattice Calculation ◽  
Kaon Decays ◽  
The Standard Model

We discuss the RBC & UKQCD collaborations’ recent [1] lattice calculation of ϵ′, the measure of direct CP-violation in kaon decays. This result significantly improves on our previous 2015 calculation, with nearly 4× the statistics and more reliable systematic error estimates. We discuss how our results demonstrate the Standard Model origin of the ΔI = 1/2 rule, and present our plans for future calculations.

scholarly journals Flavor physics: Precision as an avenue to discovery

2020 ◽  
Vol 35 (01) ◽  
pp. 1930018
Author(s):  
Diego Guadagnoli
Keyword(s):  
Cp Violation ◽  
Standard Model ◽  
Flavor Physics ◽  
Standard Model Prediction ◽  
New Physics ◽  
Effective Theory ◽  
Theory Approach ◽  
Long Distance ◽  
The Standard Model ◽  
The Impact

This paper describes the work pursued in the years 2008–2013 on improving the Standard Model prediction of selected flavor-physics observables. The latter includes: (1) [Formula: see text], that quantifies indirect CP violation in the [Formula: see text] system and (2) the very rare decay [Formula: see text], recently measured at the LHC. Concerning point (1), the paper describes our reappraisal of the long-distance contributions to [Formula: see text],[Formula: see text] that have permitted to unveil a potential tension between CP violation in the [Formula: see text]- and [Formula: see text]-system. Concerning point (2), the paper gives a detailed account of various systematic effects pointed out in Ref. 4 and affecting the Standard Model [Formula: see text] decay rate at the level of 10% — hence large enough to be potentially misinterpreted as nonstandard physics, if not properly included. The paper further describes the multifaceted importance of the [Formula: see text] decays as new physics probes, for instance how they compare with [Formula: see text]-peak observables at LEP, following the effective-theory approach of Ref. 5. Both cases (1) and (2) offer clear examples in which the pursuit of precision in Standard Model predictions offered potential avenues to discovery. Finally, this paper describes the impact of the above results on the literature, and what is the further progress to be expected on these and related observables.

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