scholarly journals On spin asymmetry in muon and tau decays

2018 ◽  
Vol 33 (32) ◽  
pp. 1850191
Author(s):  
A. B. Arbuzov ◽  
T. V. Kopylova ◽  
I. K. Sklyarov
Keyword(s):  
Charged Lepton ◽  
Spin Asymmetry ◽  
Second Order ◽  
Tau Leptons ◽  
Mass Ratio ◽  
Fermi Model ◽  
Tau Decays ◽  
Standard Formula ◽  
Leading Logarithm ◽  
Michel Parameters

The angular asymmetry in decays of polarized muons and tau leptons is discussed. Both the standard [Formula: see text] Fermi model and the general parametrization via Michel parameters are considered. Numerical importance of contributions suppressed by charged lepton mass ratio is underlined. Contribution of the second order QED correction is estimated in the leading logarithm approximation.

scholarly journals A second-order accurate non-intrusive staggered scheme for the interaction of ultra-lightweight rigid bodies with fluid flow

2020 ◽  
Author(s):  
Chennakesava Kadapa
Keyword(s):  
Incompressible Flows ◽  
Rigid Bodies ◽  
Relaxation Parameter ◽  
Second Order ◽  
Mass Ratio ◽  
Computationally Efficient ◽  
Efficient Scheme ◽  
Staggered Scheme ◽  
Low Mass ◽  
Low Mass Ratio

This paper presents a staggered scheme with second-order temporal accuracy for fluid-structure interaction problems involving ultra-lightweight rigid bodies. The staggered scheme is based on the Dirichlet-Neumann coupling and is non-intrusive. First, the spectral properties of the staggered scheme are studied and also compared against the monolithic scheme using a linear model problem. Later, the suitability and effectiveness of the staggered scheme for problems involving incompressible flows and lightweight rigid solids are illustrated by using the examples of galloping of a square cylinder and lock-in of a circular cylinder for mass-ratio values as low as 0.01. This is the first time in the literature flow-induced vibrations of rigid bodies with such low mass ratio values are successfully simulated using a staggered scheme. Two different fluid solvers are considered to illustrate the non-intrusive nature of the proposed scheme. Guidelines for choosing the relaxation parameter are also provided. With its iteration-free nature and with a single (relaxation) parameter, the proposed staggered scheme renders itself as an accurate and computationally efficient scheme for fluid-rigid body interaction problems, including those involving lightweight structures.

scholarly journals Second order in mass ratio radiative-recoil corrections to hyperfine splitting in muonium

1998 ◽  
Vol 58 (1) ◽  
Author(s):  
Michael I. Eides ◽  
Howard Grotch ◽  
Valery A. Shelyuto
Keyword(s):  
Hyperfine Splitting ◽  
Second Order ◽  
Mass Ratio

scholarly journals Probing charged lepton flavor violation with axion-like particles at Belle II

2021 ◽  
Vol 2021 (11) ◽  
Author(s):  
Kingman Cheung ◽  
Abner Soffer ◽  
Zeren Simon Wang ◽  
Yu-Heng Wu
Keyword(s):  
Charged Lepton ◽  
Branching Fractions ◽  
Coupling Constants ◽  
Decay Length ◽  
Lepton Flavor Violation ◽  
Tau Decays ◽  
Lepton Flavor ◽  
Flavor Violation ◽  
Belle Ii ◽  
Displaced Vertex

Abstract We study charged lepton flavor violation associated with a light leptophilic axion-like particle (ALP), X, at the B-factory experiment Belle II. We focus on production of the ALP in the tau decays τ → Xl with l = e, μ, followed by its decay via X → l−l+. The ALP can be either promptly decaying or long-lived. We perform Monte-Carlo simulations, recasting a prompt search at Belle for lepton-flavor-violating τ decays, and propose a displaced-vertex (DV) search. For both types of searches, we derive the Belle II sensitivity reaches in both the product of branching fractions and the ALP coupling constants, as functions of the ALP mass and lifetime. The results show that the DV search exceeds the sensitivity reach of the prompt search to the relevant branching fractions by up to about a factor of 40 in the long decay length regime.

scholarly journals Verification of 2D × 2D and Two-Species Vlasov-Poisson Solvers,

2018 ◽  
Vol 63 ◽  
pp. 78-108 ◽  
Author(s):  
Yann Barsamian ◽  
Joackim Bernier ◽  
Sever A. Hirstoaga ◽  
Michel Mehrenberger
Keyword(s):  
Test Problem ◽  
Single Species ◽  
Dispersion Analysis ◽  
Lagrangian Method ◽  
Second Order ◽  
Mass Ratio ◽  
Particle In Cell ◽  
First Order ◽  
Dimensional Effects ◽  
Order Dispersion

In [2], 1D×1D two-species Vlasov-Poisson simulations are performed by the semi-Lagrangian method. Thanks to a classical first order dispersion analysis, we are able to check the validity of their simulations; the extension to second order is performed and shown to be relevant for explaining further details. In order to validate multi-dimensional effects, we propose a 2D × 2D single species test problem that has true 2D effects coming from the sole second order dispersion analysis. Finally, we perform, in the same code, full 2D × 2D non linear two-species simulations with mass ratio 0:01, and consider the mixing of semi-Lagrangian and Particle-in-Cell methods.

scholarly journals Study of the Lorentz Structure of the Charged Weak Interaction in Tau Decays at Belle

2018 ◽  
Vol 46 ◽  
pp. 1860060
Author(s):  
Junya Sasaki
Keyword(s):  
Weak Interaction ◽  
Tau Lepton ◽  
Tau Decays ◽  
Preliminary Results ◽  
Lorentz Structure ◽  
Leptonic Decays ◽  
Decay Widths ◽  
Belle Experiment ◽  
Michel Parameters

To test the Lorentz structure of the charged weak interaction, we study leptonic decays of tau lepton in the Belle experiment. We perform this test through the measurement of Michel parameters which appear in the differential decay widths of leptonic tau decays. In this paper, we discuss the preliminary results of the measurement of Michel parameters at Belle.

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