• Single decay-lepton angular distributions in polarizede+e →$$\overline {tt}$$ and simple angular asymmetries as a measure of CP-violating top dipole couplingsand simple angular asymmetries as a measure of CP-violating top dipole couplings

• # Fulltext

https://www.ias.ac.in/article/fulltext/pram/061/01/0033-0050

• # Keywords

Top quark; CP violation; e+e collider

• # Abstract

In the presence of an electric dipole coupling of$$\overline {tt}$$ to a photon, and an analogous ‘weak’ dipole coupling to the Z, CP violation in the process e+e →$$\overline {tt}$$ results in modified polarization of the top and the anti-top. This polarization can be analyzed by studying the angular distributions of decay charged leptons when the top or anti-top decays leptonically. Analytic expressions are presented for these distributions when eithert or$$\overline t$$ decays leptonically, including$$\mathcal{O}$$(αs) QCD corrections in the soft-gluon approximation. The angular distributions are insensitive to anomalous interactions in top decay. Two types of simple CP-violating polar-angle asymmetries and two azimuthal asymmetries, which do not need the full reconstruction of thet or$$\overline t$$, are studied. Independent 90% CL limits that may be obtained on the real and imaginary parts of the electric and weak dipole couplings at a linear collider operating at √ s = 500 GeV with integrated luminosity 500 fb and also at √s = 1000 GeV with integrated luminosity 1000 fb have been evaluated. The effect of longitudinal electron and/or positron beam polarizations has been included.

• # Author Affiliations

1. Theory Group, Physical Research Laboratory, Navrangpura, Ahmedabad - 380 009, India

• # Pramana – Journal of Physics

Volume 97, 2023
All articles
Continuous Article Publishing mode

• # Editorial Note on Continuous Article Publication

Posted on July 25, 2019