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H. S. Song

Publications and source records attributed to H. S. Song.

68 records · Page 4Linked to original sources
arXiv1996

Color-Octet Contributions in the Associate J/psi+gamma Hadroproduction

Color-octet contributions to the associate J/psi+gamma hadroproduction are studied in detail, and found to be negligible, compared to the ordinary color-singlet contribution. Within the color-singlet model the J/psi+gamma production in the leading order is possible only through gluon-gluon fusion process. Therefore, the associate J/psi+gamma hadroproduction remains to be useful as a clean channel to probe the gluon distribution inside proton, to study heavy quarkonia production mechanism, and to find proton's spin structure.

hep-ph↗
arXiv1996

Color-octet heavy quarkonium productions in Z0 decays at LEP

We consider the energy and the polar angle distributions of J/ψ's produced via the color-singlet and the color-octet (^3S_1^{(8)}) mechanisms in Z^0 \to J/ψ+X at LEP. Since both distributions of the J/ψproduced via color-octet mechanism are significantly different from those via color-singlet mechanism, these observables can be used as tests of color-octet production mechanism for heavy quarkonia. We also discuss Z^0 \rightarrow Υ+ X and W \to J/ψ( or Υ) + X in brief.

hep-ph↗
arXiv1995

Polarization effects in electroweak vector boson productions

The electroweak production processes of vector bosons, $e^+ e^- \rightarrow Z γ$, $γe \rightarrow Ze$, and $γe \rightarrow W ν$ are considered simultaneousely and in the Standard model the covariant polarization density matrices of vector bosons for these processes are obtained explicitly from one of the processes, $γe \rightarrow Z e$. The effect of the photon polarization as well as the vector meson polarization is considered and some special cases are discussed.

hep-ph↗
arXiv1995

Factorization in processes of graviton scattering off electron for Z and W productions

The study of factorization in linearized gravity is extended to the graviton scattering processes with an electron for the massive vector boson productions such as $g e \rightarrow Z e$ and $g e \rightarrow W ν_e$. It is shown that every transition amplitude is completely factorized due to gravitational gauge invariance and Lorentz invariance. Also the explicit values of vector boson polarizations are obtained.

hep-th↗
arXiv1995

Chiral perturbation theory vs. vector meson dominance in the decays $ϕ\to ργγ$ and $ϕ\to ωγγ$

It is pointed out that the radiative decays of a $ϕ$ meson, $\phirho$ and $\phiom$, receive dominant contributions from the pseudoscalar ($P = η, η^{'}$) exchanges. Using the vector meson dominance model, we find that $B (\phirho) \approx 1.3 \times 10^{-4}$ and $B (\phiom) \approx 1.5 \times 10^{-5}$, which are mainly from the $η^{'}$ pole. Thus, these decays are well within the reach of the $ϕ$ factory. Our estimates are a few orders of magnitude larger than the chiral loop contributions in the heavy vector meson chiral lagrangian, which is about ( a few ) $\times 10^{-9}$.

hep-ph↗
arXiv1995

Inclusive $S-$wave charmonium productions in $B$ decays

The inclusive $S-$wave charmonium production rates in $B$ decays are considered using the Bodwin-Braaten-Lepage (BBL) approach, including the relativistic corrections and the color-octet mechanism suggested as a possible solution to the $ψ^{'}$ puzzle at the Tevatron. We first consider relativistic and radiative corrections to $J/ψ\rightarrow e^{+} e^{-}$ and $J/ψ\rightarrow$ Light Hadrons (LH), in order to determine two nonperturbative parameters, $\langle J/ψ| O_{1} (^{3}S_{1}) | J/ψ\rangle$, $\langle J/ψ| P_{1} (^{3}S_{1}) | J/ψ\rangle$, in the factorization formulae for these decays. Using these two matrix elements and including the color-octet $c\bar{c}(^{3}S_{1})$ state contribution, we get a moderate increase in the decay rates for $B$ decays into $J/ψ~({\rm or}~ψ^{'}) ~+ X$. Our results, $B(B \rightarrow J/ψ~({\rm or}~ψ^{'}) + X) = 0.58~(0.23) \%$ for $M_{b} = 5.3$ GeV, get closer to the recent CLEO data. As a byproduct, we prefer a larger decay rate for $η_{c} \rightarrow$ LH compared to the present data.

hep-ph↗
arXiv1995

INVESTIGATION OF $WWγ$ COUPLINGS

We investigated how measurements of weak boson production at high energy $ep$ and $eγ$ collisions can provide important information on anomalous $WWγ$ couplings. We also considerd the sinlge muon production through the virtual $W$-decay at the Pohang Light Source (PLS) facility, and found this process is not adequate to be detected at the PLS until a large luminosity ($\sim 10^{33}$/sec/cm$^2$) Free Electron Laser is installed.

hep-ph↗
arXiv1994

The simplest form of the $κ$ and $κ^2$ order graviton self-interaction Lagrangian density in the weak field approximation

We derive the simplest form of the $κ(κ^2)$ order graviton self-interaction Lagrangian density $\lag{1}(\lag{2})$ in the weak field approximation. With the divergenceless condition, de Donder gauge and some combinatoric techniques, we derive the mathematically independent basis expressions for $\lag{1}(\lag{2})$ composed of 8(24) terms. By using the basis expressions $\lag{1}(\lag{2})$ is reduced to 6(18) terms.

hep-ph↗
arXiv1994

Factorization and polarization in linearized gravity

We investigate all the four-body graviton interaction processes: $gX\rightarrow γX$, $gX\rightarrow gX$, and $gg\rightarrow gg$ with $X$ as an elementary particle of spin less than two in the context of linearized gravity except the spin-3/2 case. We show explicitly that gravitational gauge invariance and Lorentz invariance cause every four-body graviton scattering amplitude to be factorized. We explore the implications of this factorization property by investigating polarization effects through the covariant density matrix formalism in each four-body graviton scattering process.

hep-th↗
arXiv1993

Factorization in graviton interactions

The study of factorization in the linearized gravity is extended to the graviton scattering processes with a massive scalar particle, with a massless vector boson and also with a graviton. Every transition amplitude is shown to be completely factorized and the physical implications of their common factors are discussed.

hep-ph↗
arXiv1993

Probing $WWγ$ Couplings from $σ_{tot}(W)/σ_{tot}(Z)$ in High Energy ep Collisions

We investigate the sensitivity of total cross sections of $e+p \rightarrow W,Z$ to CP-conserving non-standard $WWγ$ couplings. We include all the important production mechanisms and study the dependence of the total $W$ cross sections on the anomalous $WWγ$ couplings, $κ$ and $λ$. We argue that the ratio of $W$ and $Z$ production cross sections is particularly well suited, being relatively insensitive to uncertainties in the theoretical and experimental parameters.

hep-ph↗
arXiv1993

Anomalous Gauge-Boson Couplings in High Energy ep Collisions

We investigate the sensitivity of total cross sections of $e+p \rightarrow W,Z$ to CP-conserving non-standard $WWγ$ couplings. We include all the important production mechanisms and study the dependence of the total $W$ cross sections on the anomalous $WWγ$ couplings, $κ$ and $λ$. We argue that the ratio of $W$ and $Z$ production cross sections is particularly well suited, being relatively insensitive to uncertainties in the theoretical and experimental parameters.

hep-ph↗
arXiv1993

Factorization of gravitational Compton scattering amplitude in the linearized version of general relativity

Gravitational Compton scattering process with a massive fermion is studied in the context of the linearized gravity. Gravitational gauge invariance and graviton transversality cause the transition amplitude to be factorized into that of scalar QED Compton scattering and that of fermion QED Compton scattering with an overall kinematical factor. The factorization is shown explicitly and its physical implications are discussed.

hep-ph↗