arXiv subjects
Publications and source records attributed to Jae Kwan Kim.
We suggest a strategy for detecting $b$ polarization effects in $e^+e^-$ annihilation on $Z$ resonance. Using two types of inclusive leptonic samples with different ${Λ_b}$ fractions in $Z \ra b\bar{b}$ events, the $b$ polarization effects may be detected without large uncertainties of $b$ fragmentation and ${Λ_b}$ decay model.
We implement global fits to LEP data with the \non interactions. Consistent $R_b$ with experimental value and consistent $\as(M_Z^2)$ with that from low energy experiments are obtained. We also find that the $\xx$ is better than the Standard Model. And we argue that other kinds of new physics are needed to explain the difference between the values of $\as(M_Z^2)$ from low energy experiments and from the 3-jet ratio.
We study the approximate flavour symmetries imposed on the lepton sector assuming see-saw mechanism as the neutrino mass structure. We apply the symmetry to various neutrino phenomenologies and obtain constraints on neutrino masses and mixings.
We developed the new parton model approach for exclusive semileptonic decays of $B$-meson to $D,~D^*$ by extending the inclusive parton model, and by combining with the results of the HQET, motivated by Drell-Yan process. Without the nearest pole dominance ansätze, we {\bf derived} the dependences of hadronic form factors on $q^2$. We also calculated numerically the slope of the Isgur-Wise function, which is consistent with the experimental results.
In the Heisenberg picture, the generalized invariant and exact quantum motions are found for a time-dependent forced harmonic oscillator. We find the eigenstate and the coherent state of the invariant and show that the dispersions of these quantum states do not depend on the external force. Our formalism is applied to several interesting cases.
We consider a process $K_{L e5} ( K_{L} \rightarrow π^{0} π^{0} π^{\pm} e^{\mp} ν)$ as a standard model background to the experiment $K_{L} \rightarrow π^{0} μ^{\pm} e^{\mp}$, which seeks for possible violation of lepton family number. Using the lowest order chiral lagrangian, we find that the branching ratio for $K_{L} \rightarrow π^{0} π^{0} π^{\pm} e^{\mp} ν$ to be $6.2 \times 10^{-12}$. A similar decay $K_{L} \rightarrow π^{\mp} π^{\mp} π^{\pm} e^{\pm} ν$ has a branching ratio, $1.7 \times 10^{-11}$.
We calculate the decay rate for inclusive $B \rightarrow τνX$ decays in a two Higgs doublet model using heavy quark expansion and operator product expansion. Combined with the recent measurement of Br($B \ra τνX$), we find a limit $\tan β< 0.58 m_H/\mbox{GeV}$ at 90\%\ C.L..
In order to study the end-point spectrum of inclusive semileptonic $b \rightarrow u$ decays, we investigate the parton model motivated by deep inelastic scattering process. The reliability of the model is carefully examined by comparing the decay rates and the lepton spectra for $b \rightarrow c$ decay with those of the heavy quark effective theory. We also compute the decay rates of the inclusive semileptonic decay into tau lepton in terms of the parton model, which give another test of the model independently. We conclude that one can make the parton model consistent with the heavy quark effective theory, and it would be phenomenologically useful in extracting $|V_{ub}|$.
In topologically massive QED$_{2+1}$ with $N$ flavours, there is the possibility that two equal-charged fermions can form a bound state pair in either s-wave or p-wave. We are concerned about the s-wave pairs and obtain the low energy effective action describing them. It is shown that the fermion pairs behave like doubly charged spin-1 bosons and, when they condense, the gauge field aquires the longitudinal mass. The approximate $SU(2)$ symmetry due to the similarity between the fermion pairs and the gauge field is discussed.
The effective action is derived for a self-interacting theory with a finite fixed $O(2)$ charge at finite temperature in curved spacetime. We obtain the high temperature expansion of the effective action in the weak coupling limit. In the relativistic temperature, we discuss about the phase transition in a homogeneous spacetime.