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C. S. Kim

Publications and source records attributed to C. S. Kim.

At least 163 records · Page 9Linked to original sources
arXiv2004

Time-dependent density-functional theory approach to nonlinear particle-solid interactions in comparison with scattering theory

An explicit expression for the quadratic density-response function of a many-electron system is obtained in the framework of the time-dependent density-functional theory, in terms of the linear and quadratic density-response functions of noninteracting Kohn-Sham electrons and functional derivatives of the time-dependent exchange-correlation potential. This is used to evaluate the quadratic stopping power of a homogeneous electron gas for slow ions, which is demonstrated to be equivalent to that obtained up to second order in the ion charge in the framework of a fully nonlinear scattering approach. Numerical calculations are reported, thereby exploring the range of validity of quadratic-response theory.

cond-mat.mtrl-sci↗
arXiv2004

Time dependent CP asymmetry in $B^0 \to ρ^0 γ$ decay to probe the origin of CP violation

Since the CP violation in the $B$ system has been investigated up to now only through processes related to the $B$--$\bar{B}$ mixing, urgently required is new way of study for the CP violation and establishing its origin in the $B$ system independent of the mixing process. In this work, we explore the exclusive $ B^0 \to ρ^0 γ$ decay to obtain the time-dependent CP asymmetry in $b \to d$ decay process in the standard model and the supersymmetric model. We find that the complex RL and RR mass insertion to the squark sector in the MSSM can lead to a large CP asymmetry in $b \to d γ$ decay through the gluino-squark diagrams, which is not predicted in the Standard Model induced by the $B$--$\bar{B}$ mixing.

hep-ph↗
arXiv2004

Implication of the weak phase $β$ measured in $B \to ργ$ decay

We explore the exclusive $ B^0 \to ρ^0 γ$ decay to obtain the time-dependent CP asymmetry in $b \to d γ$ decay process. We find that the complex RL and RR mass insertion to the squark sector in the MSSM can lead to a large deviation of CP asymmetry from that predicted in the Standard Model.

hep-ph↗
arXiv2004

Neutral Higgs Boson Production and CP Violation at LC

We study the neutral Higgs boson production at the $e^- e^+$ linear collider in the two Higgs doublet model with the CP violation. The CP-even and CP-odd scalars are mixed in this model, which affects the production process of neutral Higgs boson.

hep-ph↗
arXiv2004

GeV to TeV astrophysical tau neutrinos

Neutrinos with energy greater than GeV are copiously produced in the p(A,p) interactions occurring in several astrophysical sites such as (i) the earth atmosphere, (ii) our galactic plane as well as in (iii) the galaxy clusters. A comparison of the tau and mu neutrino flux in the presence of neutrino oscillations from these three representative astrophysical sites is presented. It is pointed out that the non-atmospheric tau neutrino flux starts dominating over the downward going atmospheric tau neutrino flux for neutrino energy E as low as 10 GeV. This energy value is much lower than the energy value, E \geq 5\times 10^4 GeV, estimated for the dominance of the non-atmospheric mu neutrino flux, in the presence of neutrino oscillations. Future prospects for possible observations of non-atmospheric tau neutrino flux are briefly mentioned.

hep-ph↗
arXiv2004

B -> eta^(\prime) l nu decays and the flavor-singlet form factor

We study semileptonic decays B -> eta^(\prime) l nu, taking into account the flavor-singlet contribution (F^{singlet}_+) to the B -> eta^(\prime) form factors, which arises from the two-gluon emission in a decaying B meson. It has been recently pointed out that, in addition to large weak annihilation effects, the unknown value of F^{singlet}_+ prevents accurate theoretical estimates in the analysis of B -> eta^\prime K decays in QCD factorization. We present a certain method to determine F^{singlet}_+ with a reasonable accuracy, using B -> eta^(\prime) l nu and B -> pi l nu decays. We also investigate the possible effect of F^{singlet}_+ on the estimated branching ratios (BRs) for B -> eta^(\prime) l nu and find that the BR for B -> eta^\prime l nu is particularly sensitive to the effect of F^{singlet}_+.

hep-ph↗
arXiv2004

Resummed pole mass, static potential, and Upsilon(1S) spectrum

Employing the heavy quark pole mass and static potential that were obtained from resummation of the renormalon-caused large order behavior to all orders, and matching the resummed static potential to the long distance Cornell potential we obtain a new estimate of the bottom quark mass % $m_b^{\bar{\text % MS}}=4.20$ GeV at $α_s(M_z)=0.118$ from $Υ$(1S) system. We point out that the pure perturbative QCD approach to $Υ$(1S) spectrum should have a sizable systematic error of about 100 MeV, due to the absence of the long distance confining potential, and that the incorporation of the latter is essential for accurate determination of the ground state energy. We also recalculate the nonperturbative Leutwyler-Voloshin effect using a resummed octet potential matched to a confining linear potential, and obtain a result that is substantially smaller than the estimates based on Coulombic potentials. The hyperfine splitting is estimated to be $50 \pm 8$ MeV at $α_s(M_z)=0.118$.

hep-ph↗
arXiv2004

Decay Constants of Heavy Meson of $0^-$ State in Relativistic Salpeter Method

The decay constants of pseudoscalar heavy mesons of $0^-$ state are computed by means of the relativistic (instantaneous) Salpeter equation. We solved the full Salpeter equation without making any further approximation, such as ignoring the small component wave function. Therefore, our results for the decay constants include the complete relativistic contributions from the light and the heavy quarks. We obtain $F_{D_s} \approx 248 \pm 27 $, $F_{D} \approx 230 \pm 25 (D^0,D^\pm)$, $F_{B_s} \approx 216 \pm 32 $, $F_{B} \approx 196 \pm 29 (B^0,B^\pm)$, $F_{B_c} \approx 322 \pm 42 $ and $F_{η_c} \approx 292 \pm 25 $ MeV.

hep-ph↗
arXiv2004

Implications of SNO and BOREXINO results on Nuetrino Oscillations and Majorana Magnetic Moments

Using the recent measurement of SNO salt phase experiment, we investigate how much the solar neutrino flux deficit observed at SNO could be due to $ν_e$ transition into antineutrino. Our analysis leads to rather optimistic conclusion that the SNO salt phase data may indicate the existence of Majorana magnetic moment. The prospect for the future BOREXINO experiment is also discussed.

hep-ph↗
arXiv2004

CP Asymmetries of $B \to ϕK$ and $B \to η^{(\prime)} K$ Decays Using a Global Fit in QCD Factorization

We analyze the CP asymmetries of $B\to ϕK$ and $B\to η^{(\prime)} K$ modes in the QCD improved factorization framework. For our calculation we use the phenomenological parameters predetermined from the global fit for the available $B\to PP$ and $VP$ modes (without the quark-level subprocess $b\to s\bar s s$). We show that the large negative $\sin (2ϕ_1)_{ϕK_s}$ and the large branching ratio for $B^{\pm}\to η' K^{\pm}$ can be simultaneously explained in the context of supersymmetry (SUSY). The R-parity conserving SUGRA models are used and their parameter space is constrained with the observed dark matter relic density along with other experimental constraints. The R-parity violating SUSY models are also used to show that they can provide solutions. We calculate the CP asymmetries for different $B^{\pm (0)} \to ϕK^{\pm (0)}$ and $B^{\pm (0)} \to η^{(')} K^{\pm (0)}$ modes and show that the SUSY model predictions are consistent with the available experimental data.

hep-ph↗
arXiv2004

An Analysis of $B \to η' K$ Decays Using a Global Fit in QCD Factorization

In the framework of QCD factorization, we study $B^{+(0)} \to η' K^{+(0)}$ decays. In order to more reliably determine the phenomenological parameters $X_H$ and $X_A$ arising from end-point divergences in the hard spectator scattering and weak annihilation contributions, we use the global analysis for twelve $B \to PP$ and $VP$ decay modes, such as $B \to ππ$, $πK$, $ρπ$, $ρK$, etc, but excluding the modes whose (dominant) internal quark-level process is $b \to s \bar s s$. Based on the global analysis, we critically investigate possible magnitudes of $X_{H,A}$ and find that both large and small $X_{H,A}$ terms are allowed by the global fit. In the case of the large $X_{H,A}$ effects, the standard model (SM) prediction of the branching ratios (BRs) for $B^{+(0)} \to η' K^{+(0)}$ is large and well consistent with the experimental results. In contrast, in the case of the small $X_{H,A}$ effects, the SM prediction for these BRs is smaller than the experimental data. Motivated by the recent Belle measurement of $\sin (2ϕ_1)$ through $B^0 \to ϕK_s$, if we take into account possible new physics effects on the quark-level process $b \to s \bar s s$, we can explicitly show that these large BRs can be understood even in the small $X_{H,A}$ case. Specifically, we present two new physics scenarios: R-parity violating SUSY and R-parity conserving SUSY.

hep-ph↗
arXiv2003

Probing the Radion-Higgs mixing at hadronic colliders

In the Randall-Sundrum model, the radion-Higgs mixing is weakly suppressed by the effective electroweak scale. One of its novel features would be a sizable three-point vertex of KK graviton-Higgs-radion. We explored the potential of the Fermilab Tevatron and the CERN LHC in probing the radion-Higgs mixing via the associated production of the radion with the Higgs boson. The observation of the rare decay of the KK gravitons into a Higgs and a radion is then the direct and exclusive signal of the radion-Higgs mixing. We also studied all the partial decay widths of the KK gravitons in the presence of the radion-Higgs mixing, and found that if the mixing parameter is of order one, the decay rate into a radion and a Higgs boson becomes as large as that into a Higgs boson pair, with the branching ratio of order 0.001.

hep-ph↗
arXiv2003

Remarks on the recently observed B decays into $f_X(1300) K$ and $J/ψK_X^*(1430)$

In light of the recent experimental results on decays $B^+ \to f_X(1300) K^+$ and $B^{\pm(0)} \to J/ψK_X^{*\pm(0)}(1430)$ from Belle, we study the $B \to P(V) S$ type decays, $B^{\pm(0)} \to f_0(1370) K^{\pm(0)}$ and $B^{\pm(0)} \to J/ψK_0^{*\pm(0)}(1430)$, in comparison with the $B \to P(V) T$ type decays, $B^{\pm(0)} \to f_2(1270) K^{\pm(0)}$ and $B^{\pm(0)} \to J/ψK_2^{*\pm(0)}(1430)$. We calculate the BRs for these decays by using the form factors obtained in the ISGW2 model [the improved version of the original Isgur-Scora-Grinstein-Wise (ISGW) model], as well as the ISGW model for comparison. The ratios of ${\cal B}(B \to P(V)S) / {\cal B}(B \to P(V)T)$ are also presented.

hep-ph↗
arXiv2003

New Interpretation on the Solar Neutrino Flux with Flavor Mixing and Majorana Magnetic Moment

A simple and model-independent method is proposed to extract information on solar $ν_e$ transition into antineutrinos via the spin flavor precession (SFP) from the measurements of solar neutrino flux at SNO and Super-Kamiokande. Incorporating the KamLAND experimental results, we examine how large the suppression of the solar neutrino flux could be due to the SFP mechanism in the context of the hybrid scenario with two-flavor neutrino and antineutrino mixings.

hep-ph↗
arXiv2003

Heavy Baryonic Decays of Λ_b \to Λη^{(\prime)} and Nonspectator Contribution

We calculate the branching ratios of the hadronic Λ_b decays to ηand η^\prime in the factorization approximation where the form factors are estimated via QCD sum rules and the pole model. Our results indicate that, contrary to B\to Kη^{(\prime)} decays, the branching ratios for Λ_b\toΛηand Λ_b\toΛη^\prime are more or less the same in the hadronic Λ_b transitions. We estimate the branching ratio of Λ_b\toΛη^{(\prime)} to be 10.80 (10.32)\times 10^{-6} in QCD sum rules, and 2.78 (2.96)\times 10^{-6} in the pole model. We also estimate the nonfactorizable gluon fusion contribution to Λ_b\toΛη^\prime decay by dividing this process into strong and weak vertices. Our results point to an enhancement of more than an order of magnitude due to this mechanism.

hep-ph↗
arXiv2003

A probe of the Radion-Higgs mixing in the Randall-Sundrum model at e^+ e^- colliders

In the Randall-Sundrum model, the radion-Higgs mixing is weakly suppressed by the effective electroweak scale. A novel feature of the existence of gravity-scalar mixing would be a sizable three-point vertex among the KK graviton, Higgs and radion. We study this vertex in the process e^+ e^- -> h phi, which is allowed only with a non-zero radion-Higgs mixing. It is shown that the angular distribution is a unique characteristic of the exchange of massive spin-2 gravitons, and the total cross section at the future e^+ e^- collider is big enough to cover a large portion of the parameter space where the LEP/LEP II data cannot constrain.

hep-ph↗
arXiv2002

A Flexible Parametrization of CKM matrix via Singular-Value-Decomposition Method

We investigate a flexible method in which we can test the unitarity of the quark flavor mixing matrix step-by-step. Singular-Value-Decomposition (SVD) techniques are used in analyzing the mixing matrix over a broader parameter region than the unitarity region. Unitary constraints make us extract CP violating properties without any specific parametrization when the magnitudes of at least three mixing matrix elements in three generation quark mixing are given. This method can also be applied to the analysis of lepton flavor mixing, in which only a few moduli are presently measured.

hep-ph↗