scholarly journals CP violation in mixing and oscillations in a toy model for leptogenesis with quasi-degenerate neutrinos

2021 ◽  
Vol 2021 (4) ◽  
Author(s):  
J. Racker
Keyword(s):  
Cp Violation ◽  
Source Term ◽  
Mass Difference ◽  
Theory Model ◽  
Interference Term ◽  
Final States ◽  
Cpt Invariance ◽  
Lepton Asymmetry ◽  
First Order ◽  
Unstable Particles

Abstract We study the sources of CP violation for baryogenesis models with quasi-degenerate neutrinos. Our approach is to use the renormalized propagator in a quantum field theory model of neutrino oscillations, paying close attention to unitarity requirements. From the probabilities of lepton number violating processes obtained in this way, we derive a source term for the time evolution of the lepton asymmetry. The source term has contributions that can be identified with CP violation from mixing, oscillations and interference between both. Given that this source term does not involve processes with unstable particles in the initial or final states, neither does it require to calculate number densities of neutrinos, no subtraction of real intermediate states must be performed. In equilibrium the source term is null, as demanded by unitarity and CPT invariance, due to a cancellation between the terms coming from CP violation in mixing and oscillations. The calculations are done in a simple scalar toy model, and the resummed propagator is diagonalized at first order in the decay widths over the mass difference. We also comment on the effect of the interference term, which is mild at the order we work, but seems to become more important with increasing degeneracy.

scholarly journals Electroweak-like baryogenesis with new chiral matter

2021 ◽  
Vol 2021 (7) ◽  
Author(s):  
Kohei Fujikura ◽  
Keisuke Harigaya ◽  
Yuichiro Nakai ◽  
Ruoquan Wang
Keyword(s):  
Phase Transition ◽  
Gauge Symmetry ◽  
Cp Violation ◽  
Standard Model ◽  
Dipole Moments ◽  
Dark Matter Candidate ◽  
Lepton Asymmetry ◽  
First Order ◽  
The Standard Model ◽  
Concrete Realization

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.

Analytic Calculations of the Branching Ratio and CP Violation in Bs0 → Ds+Ds− Decay

2020 ◽  
Vol 35 (15) ◽  
pp. 2050122
Author(s):  
H. R. Khan ◽  
E. H. Raslan ◽  
R. A. Reem
Keyword(s):  
Cp Violation ◽  
Decay Width ◽  
Branching Ratio ◽  
Gluon Condensate ◽  
Analytic Calculation ◽  
Experimental Measurements ◽  
Meson Decays ◽  
First Order ◽  
Theoretical Predictions ◽  
Charge Parity

We present an analytic calculation of Branching Ratio (BR) and Charge-Parity (CP) violating asymmetries of the [Formula: see text] meson decays to [Formula: see text] by calculating the amplitude and the decay width of the process including the chiral loop and gluon condensate to first-order. We find the BR of [Formula: see text] which is in agreement with other experimental measurements and theoretical predictions. We also calculate the direct CP violation, CP violation in mixing and CP violation due to interference which are [Formula: see text], [Formula: see text] and [Formula: see text], respectively.

The Investigation of the First Order Size Effect in Micro-Plastic Forming

2011 ◽  
Vol 464 ◽  
pp. 592-595
Author(s):  
Yun Wang ◽  
Jing Jing Wang ◽  
Jia Xi Wang ◽  
Zhen Ying Xu ◽  
Pei Long Dong
Keyword(s):  
Size Effects ◽  
Rapid Development ◽  
Theory Model ◽  
Electronic Industry ◽  
Layer Model ◽  
Micro Forming ◽  
First Order ◽  
Micro Parts ◽  
Plastic Forming

With the rapid development of MEMS and electronic industry, the demands for micro-parts are increasing gradually. However, size effects make the traditional forming theories and deformation mechanism not suitable in micro forming field. In this paper, we introduced the classification of the size effects. It pointed out that the size effects can be divided into the first order and the second order size effects in the micro-forming. For the first order size effects, the theory model was established based on the surface layer model. It also clarified the phenomenon that flow stress of the blank reduced with the increase of the ratio of grain size and thickness (t decreases or d increases). Finally, the model was verified with the experimental results of the first order size effects in the references, confirming the effectiveness of the theoretical model. It provides a method to theoretically and experimentally study the micro-plastic forming.

WHAT DOES μ - τ SYMMETRY IMPLY ABOUT LEPTONIC CP VIOLATION?

2007 ◽  
Vol 16 (05) ◽  
pp. 1373-1381 ◽  
Author(s):  
TEPPEI BABA
Keyword(s):  
Experimental Data ◽  
Cp Violation ◽  
Symmetry Breaking ◽  
Neutrino Mass ◽  
Mass Matrix ◽  
Mass Difference ◽  
Atmospheric Neutrino ◽  
Symmetric Part ◽  
Neutrino Mixing ◽  
Mixing Angles

The μ - τ symmetry can reproduce the consistent results with experimental data of θ13, and θ23 (θ13, and θ23 respectively denote the νe - ντ, and νμ - ντ, mixing angles). However, we can not address the issue of the leptonic CP violation in μ - τ symmetric models. So we add the μ - τ symmetry breaking part to include the CP violation. We characterize leptonic CP violation in terms of three phases, where one is conventional phase δ and others are additional phases ρ and γ. These δ, ρ and γ are, respectively, the phases of νe - ντ, νe - νμ and νμ - ντ mixings. The ρ and γ are redundant but the effect of ρ remains in the leptonic CP violation which is characterized by δ + ρ. The δ arises from the μ - τ symmetry breaking part of the Meμ and Meτ while ρ arises from of μ - τ symmetric part of the Meμ and Meτ, where Mij stands for ij (i,j = e,μ,τ) element of M(= [Formula: see text] for Mν being a flavor neutrino mass matrix). Moreover, θ23 can be exactly estimated to be: [Formula: see text] ( sin θ ∝ sin θ13 cos (δ + ρ)[Formula: see text], sin ϕ ∝ Mμμ - Mττ, where [Formula: see text] is the solar neutrino mass difference squared). The conditions of maximal atmospheric neutrino mixing are given by [Formula: see text] and Mμμ = Mττ,which indicate maximal Dirac CP violation.

scholarly journals CPLEAR data on semileptonic decay of K0, K̄0 and the mass difference of KL0 and KS0 mesons

2015 ◽  
Vol 39 ◽  
pp. 1560101
Author(s):  
Stanislav Dubnicka ◽  
Anna-Zuzana Dubnickova
Keyword(s):  
Cp Violation ◽  
Semileptonic Decay ◽  
Mass Difference ◽  
Time Dependent ◽  
Theoretical Formula ◽  
Difference Formula

It is demonstrated that for a determination of the mass difference of the [Formula: see text] and [Formula: see text] mesons an explicit theoretical formula to be derived by an assumption of the CP-conservation has been used by CPLEAR Collaboration in a fitting of the time-dependent CPLEAR data on ASYMMETRY. So, in such procedure the mass difference [Formula: see text] of the [Formula: see text] and [Formula: see text] mesons has been found and in no case [Formula: see text] one as in this case the CP-violation has to be considered.

DEFECT THEORY OF SOLID–LIQUID TRANSITION AND INTERFACE

1993 ◽  
Vol 07 (21) ◽  
pp. 1373-1381
Author(s):  
A. FERRAZ
Keyword(s):  
Field Theory ◽  
Phase Transition ◽  
Surface Tension ◽  
Theory Model ◽  
Planar Interface ◽  
Elastic Continuum ◽  
First Order ◽  
Liquid Transition ◽  
The Stability ◽  
Solid Liquid

In this work, we develop a field theory model for the solid–liquid transition and planar interface induced by dislocation lines in an elastic continuum. We show that the phase transition which emerges from our model is of first order kind. We calculate the interface solution, the surface tension and, finally, we end up discussing the stability of the field solutions.

NEW RESULT OF DIRECT CP VIOLATION IN B → π+π-π+π-

2011 ◽  
Vol 26 (17) ◽  
pp. 2899-2912 ◽  
Author(s):  
GANG LÜ ◽  
ZHEN-HUA ZHANG ◽  
XIU-YING LIU ◽  
LI-YING ZHANG
Keyword(s):  
Experimental Data ◽  
Cp Violation ◽  
Invariant Mass ◽  
Branching Ratios ◽  
Effective Parameter ◽  
Matrix Elements ◽  
Strong Constraint ◽  
Ckm Matrix ◽  
First Order ◽  
Isospin Violation

In the framework of factorization, based on the first-order of isospin violation, we study direct CP violation in the decay of [Formula: see text] including the effect of ρ–ω mixing. The CP violation depends strongly on Cabibbo–Kobayashi–Maskawa (CKM) matrix elements and the effective parameter, Nc. Recently, the experimental data for the branching ratios of [Formula: see text] are accurate and we can give the strong constraint on the range of Nc. We find that the CP violating asymmetry is large and ranges from -82% to -98% via ρ–ω mixing mechanism when the invariant mass of the π+π- pair is in the vicinity of the ω resonance. We also discuss the possibility to observe the predicted CP violating asymmetries at the LHC.

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