arXiv subjects

Sin Kyu Kang

Publications and source records attributed to Sin Kyu Kang.

117 records · Page 7Linked to original sources

arXiv1997

New Class of Quark Mass Matrix and Calculability of Flavor Mixing Matrix

We discuss a new general class of mass matrix ansatz that respects the fermion mass hierarchy and calculability of the flavor mixing matrix. This is a generalization and justification of the various specific forms of the mass matrix by successive breaking of the maximal permutation symmetry. By confronting the experimental data, a large class of the mass matrices are shown to survive, while certain specific cases are phenomenologically ruled out. Also the CP-violation turns out to be maximal, when the phase of the (1,2) element of the mass matrix is $π/2$.

hep-ph↗

arXiv1997

Higgs Boson Mass Bounds in the Standard and Minimal Supersymmetric Standard Model with Four Generations

We study the question of distinguishability of the Higgs sector between the standard model with four generations(SM4) and the minimal supersymmetric standard model with four generations (MSSM4). We find that a gap exists between the SM4 and MSSM4 Higgs boson masses for a range of the fourth generation fermion mass considered in the analysis at a fixed top quark mass. We also compare the Higgs boson mass bounds in these models with those in the standard and the minimal supersymmetric standard models.

hep-ph↗

arXiv1997

Field Theory for the Standard Model

We review the origin of the standard electroweak model and discuss in great detail the on-shell renormalization scheme of the standard model as a field theory. One-loop radiative corrections are calculated by the dimensional regularization and the dominant higher-order corrections are also discussed. We then show how well the standard model withstands the precision test against the LEP and SLD data along with its prediction on the indirect bound of the Higgs boson mass $m_H$. The uncertainty in $m_H$ and in $Z-$decay parameters due to the experimental uncertainties in $m_t, M_W$ and QED and QCD couplings is also discussed.

hep-ph↗

arXiv1996

Almost maximally broken permutation symmetry for neutrino mass matrix

Assuming three light neutrinos are Majorana particles, we propose mass matrix ansatz for the charged leptons and Majorana neutrinos with family symmetry $S_{3} $ broken into $S_{1}$ and $S_{2}$, respectively. Each matrix has three parameters, which are fixed by measured charged lepton masses, differences of squared neutrino masses relevant to the solar and the atmospheric neutrino puzzles, and the masses of three light Majorana neutrinos as a candidate for hot dark matter with $\sum |m_ν| \sim 6 eV$. The resulting neutrino mixing is compatible with the data for the current upper limit, $ < m_{ν_e} >_{th} < 0.8 eV$, of neutrino-less double beta decay experiments, and the current data for various types of neutrino oscillation experiments. One solution of our model predicts that $ν_μ \rightarrow ν_τ$ oscillation probability is about $< 0.008$ with $Δm^{2} \sim 10^{-2} eV^2$, which may not be accessible at CHORUS and other ongoing experiments.

hep-ph↗

arXiv1996

Critical Review of The Electroweak Precision Tests

There have been a great deal of works on the precision test of the standard model (SM) because of the incredibly precise data obtained at the LEP and the new measurements of $M_W$ and $m_t$ at the Fermilab Tevatron as well as the recent theoretical progress in the higher order radiative corrections. We will discuss some of the hidden inputs and theoretical uncertainties involved in making the predictions of the observables in the SM. From the minimal $χ^2$-fit to the experimental Z-decay parameters (with the aid of a modified ZFITTER program) in a scheme where $M_Z$, $G_μ$ and $α(M_Z)$ are taken as inputs, we can predict $M_W$ for given values of $m_H$ and $m_t$. The current world average value of $M_W$ definitely favor nonvanishing electroweak radiative corrections and is consistent with a heavy $m_t$ as measured by the recent CDF report but with a heavy Higgs scalar of about 500 GeV within the context of the minimal SM. The sensitivity of and the errors in the best fit solutions due to the uncertainties in the gluonic coupling $α_s(M_Z)$ and $α(M_Z)$ are examined carefully and any trace of new physics beyond the SM implied by the data, in a particular $R_b$ and $R_c$, is also touched upon. In addition we discuss how the future precision measurements of $M_W$ and $Z$ decay parameters can determine the Higgs boson mass and distinguish the SM with radiative corrections from the minimal supersymmetric standard model (MSSM) and other extended model.

hep-ph↗

arXiv1995

The W-Boson Mass and Precision Tests of the Standard Model

We have examined the electroweak radiative corrections in the LEP precision data in view of the new measurements of $M_W$ and $m_t$ as well as the recent progress in the higher order radiative corrections. From the minimal $χ^2$-fit to the experimental Z-decay parameters (with the aid of a modified ZFITTER program), we predict that $M_W=80.29(4)(2)$ GeV where the first error is due to the uncertainty in the fitted $m_t$ for a fixed $m_H$ and the second error comes from the $m_H$ in the range of $60-1000$ GeV, which is to be compared with the current world average $M_W=80.23(18)$ GeV. The current world average value of $M_W$ and the 1994 LEP data definitely favor nonvanishing electroweak radiative corrections and are consistent with a heavy $m_t$ as measured by the recent CDF report but with a heavy Higgs scalar of about 400 GeV within the context of the minimal standard model. The sensitivity of and the errors in the best fit solutions due to the uncertainties in the gluonic coupling $α_s(M_Z)$ and $α(M_Z)$ are also studied carefully. In addition we discuss how the future precision measurements of $M_W$ can provide a decisive test for the standard model with radiative corrections and give a profound implication for the measurement of t-quark and Higgs masses.

hep-ph↗

arXiv1995

Consequences of Recent Electroweak Data and W-mass for the Top Quark and Higgs Masses

We critically reexamine the precision tests of the standard model by coupling the current world average value of $M_W$ with the recent LEP electroweak data with the aid of a modified ZFITTER program to include the dominant two-loop and QCD-EW mixed terms. The results show a clear evidence of nonvanishing electroweak radiative corrections. The recent CDF $m_t$ is a solution of the minimal $χ^2$-fits to the recent LEP data set and $M_W=80.23(18)~$ GeV but with a heavy Higgs scalar, i.e., $m_t=179~$ GeV and $m_H=300~$ GeV. We discuss how sensitive $m_t$ and $m_H$ are depending on the exact value of $M_W$ even within the present uncertainty, as well as on $α_s$ and $α(M_Z)$. We show how the future improvements on $M_W$ can discriminate different values of $m_t$ and $m_H$ from the electroweak data and provide a crucial and decisive test for the standard model.

hep-ph↗

arXiv1994

Electroweak Physics at LEP

We have examined the evidence for the electroweak radiative corrections in the LEP precision data sets of 1993 and 1994 along with the intriguing possibility that the QED corrections only may be sufficient to fit the data within the framework of the minimal standard model. We find that the situation is very sensitive to the precise values of $M_W$. The current world average value of $M_W$ and the improved 1994 LEP data strongly favor nonvanishing electroweak radiative corrections and are consistent with a heavy $m_t$ as reported by CDF but with a heavy Higgs scalar of about 400 GeV. We discuss how future precision measurements of $M_W$ and $m_t$ can provide a decisive test for the standard model with radiative corrections.

hep-ph↗

arXiv1994

Electroweak Radiative Corrections, Born Approximation, and Precision Tests of the Standard Model at LEP

We have examined the evidence for the electroweak radiative corrections in the LEP precision data along with the intriguing possibility that the QED corrections only may be sufficient to fit the data. We find that the situation is very sensitive to the precise value of $M_W$. While the world average value of $M_W$ strongly favors nonvanishing electroweak radiative corrections, the QED corrections alone can account for the data within $2σ$ in the context of the standard model. We discuss how the precision measurements of $M_W$ can provide a decisive test for the standard model with radiative corrections and give a profound implication for the existence of t-quark and Higgs scalar.

hep-ph↗