arXiv subjects

Chien Yeah Seng

Publications and source records attributed to Chien Yeah Seng.

3 recordsLinked to original sources

arXiv2024

Superallowed nuclear beta decays and precision tests of the Standard Model

For many decades, the main source of information on the top-left corner element of the Cabibbo-Kobayashi-Maskawa quark mixing matrix $V_{ud}$ were superallowed nuclear beta decays with an impressive 0.01\% precision. This precision, apart from experimental data, relies on theoretical calculations in which nuclear structure-dependent effects and uncertainties play a prime role. This review is dedicated to a thorough reassessment of all ingredients that enter the extraction of the value of $V_{ud}$ from experimental data. We tried to keep balance between historical retrospect and new developments, many of which occurred in just five past years. They have not yet been reviewed in a complete manner, not least because new results are a-coming. This review aims at filling this gap and offers an in-depth yet accessible summary of all recent developments.

nucl-th↗

arXiv2019

Dispersive Evaluation of the Inner Radiative Correction in Neutron and Nuclear $β$-decay

We propose a novel dispersive treatment of the so-called inner radiative correction to the neutron and nuclear $β$-decay. We show that it requires knowledge of the parity-violating structure function $F_3^{(0)}$ that arises from the interference of the axial vector charged current and the isoscalar part of the electromagnetic current. By isospin symmetry, we relate this structure function to the charged current inelastic scattering of neutrinos and antineutrinos. Applying this new data-driven analysis we obtain a new, more precise evaluation for the universal radiative correction $Δ_{R}^{V,\,new}=0.02467(22)$ that supersedes the previous estimate by Marciano and Sirlin, $Δ_R^V=0.02361(38)$. The substantial shift in the central value of $Δ_R^V$ reflects in a respective shift of $V_{ud}$ and a considerable tension in the unitarity constraint on the first row of the CKM matrix which is used as one of the most stringent constraints on New Physics contributions in the charged current sector. We also point out that dispersion relations offer a unifying tool for treating hadronic and nuclear corrections within the same framework. We explore the potential of the dispersion relations for addressing the nuclear structure corrections absorbed in the ${\cal F}t$ values, a crucial ingredient alongside $Δ_R^V$ in extracting $V_{ud}$ from superallowed nuclear decays.

nucl-th↗

arXiv2011

Tunneling between edge states of a 2D topological insulator and a Fermi liquid lead through a quantum dot

In this paper we study a non-equilibrium resonant tunnelling problem where a non-interacting quantum dot is connected to two leads, one being the edge of an interacting 2-D topological insulator (Luttinger liquid) and the other being a usual Fermi liquid. We show that the current passing through the system can be expressed in terms of a non-equilibrium local single-particle Green's function of the Luttinger liquid lead which can be analysed using standard bosonization- Renormalization Group (RG) technique. In particular, some exact results can be extracted in the small bias limit with repulsive electron-electron interaction. A simple formula which captures the qualitative feature of the I-V relation over whole temperature and voltage bias range is being proposed and studied.

cond-mat.mes-hall↗