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

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.

2018 ◽  
Vol 175 ◽  
pp. 13020 ◽  
Author(s):  
Christopher Kelly

We discuss the ongoing effort by the RBC & UKQCD collaborations to improve our lattice calculation of the measure of Standard Model direct CP violation, ∊’, with physical kinematics. We present our progress in decreasing the (dominant) statistical error and discuss other related activities aimed at reducing the systematic errors.


1998 ◽  
Vol 13 (01) ◽  
pp. 1-93 ◽  
Author(s):  
GIANCARLO D'AMBROSIO ◽  
GINO ISIDORI

We review the Standard Model predictions of CP violation in kaon decays. We present an elementary introduction to Chiral Perturbation Theory, four-quark effective Hamiltonians and the relation among them. Particular attention is devoted to K→3π, K→ 2πγ and [Formula: see text] decays.


1989 ◽  
Vol 04 (01) ◽  
pp. 79-114 ◽  
Author(s):  
DOUGLAS A. BRYMAN

Major advances spanning several orders of magnitude in sensitivity are anticipated in the current round of experiments dealing with rare kaon decays. Observations of allowed processes, like [Formula: see text] and [Formula: see text], shed light on detailed aspects of the standard model. New sources of T or CP violation could be manifested by measurements of muon polarization in K → πμνμ and [Formula: see text] decays and by studies of reactions like [Formula: see text]. Evidence for new particles and new interactions could appear in advanced efforts to observe K → πxx′ and K → πx decays, where x and x′ represent hypothetical neutral particles, and in searches for lepton flavor violating processes [Formula: see text] and K+ → π+μe. The experiments are reviewed and their theoretical context is discussed.


2021 ◽  
Vol 2021 (7) ◽  
Author(s):  
Kohei Fujikura ◽  
Keisuke Harigaya ◽  
Yuichiro Nakai ◽  
Ruoquan Wang

Abstract We propose a framework where a phase transition associated with a gauge symmetry breaking that occurs (not far) above the electroweak scale sets a stage for baryogenesis similar to the electroweak baryogenesis in the Standard Model. A concrete realization utilizes the breaking of SU(2)R× U(1)X→ U(1)Y. New chiral fermions charged under the extended gauge symmetry have nonzero lepton numbers, which makes the B − L symmetry anomalous. The new lepton sector contains a large flavor-dependent CP violation, similar to the Cabibbo-Kobayashi-Maskawa phase, without inducing sizable electric dipole moments of the Standard Model particles. A bubble wall dynamics associated with the first-order phase transition and SU(2)R sphaleron processes generate a lepton asymmetry, which is transferred into a baryon asymmetry via the ordinary electroweak sphaleron process. Unlike the Standard Model electroweak baryogenesis, the new phase transition can be of the strong first order and the new CP violation is not significantly suppressed by Yukawa couplings, so that the observed asymmetry can be produced. The model can be probed by collider searches for new particles and the observation of gravitational waves. One of the new leptons becomes a dark matter candidate. The model can be also embedded into a left-right symmetric theory to solve the strong CP problem.


2013 ◽  
Vol 22 (03) ◽  
pp. 1330006 ◽  
Author(s):  
Z. J. AJALTOUNI ◽  
E. DI SALVO

This review paper stresses the possible connection between time-reversal violation and new physics processes beyond the standard model. In particular, this violation is proposed as an alternative to CP violation in the search for such unkown processes. Emphasis is put on the weak decays of heavy hadrons, especially beauty ones. Specific methods for extracting useful parameters from experimental data are elaborated in order to test TR symmetry. These methods could be used successfully in the analysis of the LHC data.


2006 ◽  
Vol 21 (08n09) ◽  
pp. 1738-1749 ◽  
Author(s):  
LUCA SILVESTRINI

We review the status of rare decays and CP violation in extensions of the Standard Model. We analyze the determination of the unitarity triangle and the model-independent constraints on new physics that can be derived from this analysis. We find stringent bounds on new contributions to [Formula: see text] and [Formula: see text] mixing, pointing either to models of minimal flavour violation or to models with new sources of flavour and CP violation in b → s transitions. We discuss the status of the universal unitarity triangle in minimal flavour violation, and study rare decays in this class of models. We then turn to supersymmetric models with nontrivial mixing between second and third generation squarks, discuss the present constraints on this mixing and analyze the possible effects on CP violation in b → s nonleptonic decays and on [Formula: see text] mixing. We conclude presenting an outlook on Lepton-Photon 2009.


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