arXiv subjects

Seungwon Baek

Publications and source records attributed to Seungwon Baek.

96 records · Page 6Linked to original sources

arXiv1999

Effects of supersymmetric CP violating phases on B \to X_s l^+ l^- and ε_K

We consider effects of CP violating phases in μand A_t parameters in the effective supersymmetric standard model on B\to X_s l^+ l^- and ε_K. Scanning over the MSSM parameter space with experimental constraints including edm constraints from Chang-Keung-Pilaftsis (CKP) mechanism, we find that the Br(B\to X_s l^+ l^-) can be enhanced by upto \sim 85 % compared to the standard model (SM) prediction, and its correlation with Br(B \to X_s γ) is distinctly different from the minimal supergravity scenario. Also we find 1 \lesssim ε_K / ε_K^{SM} \lesssim 1.4, and fully supersymmetric CP violation in K_L \to ππis not possible. Namely, |ε_K^{\rm SUSY}| \lesssim O(10^{-5}) if the phases of μand A_t are the sole origin of CP violation.

hep-ph↗

arXiv1998

Evolution equation for the heavy quark distribution function in the parton model approach

We explore the perturbative QCD corrections to the inclusive semileptonic decays of $B$ mesons. In inclusive $B$ decay processes the parton picture works well and the scaling feature manifests because the mass of $b$ quark is larger than the QCD scale. Due to this property, the decay rate may be expressed by a single structure function describing the light-cone distribution of $b$ quark apart from the kinematic factor. We derive a $q^2$ evolution equation for the distribution function, which violates the scaling property through the Altarelli-Parisi type approach. The evolution equation is numerically solved and its phenomenological implications are also discussed.

hep-ph↗

arXiv1998

Polarized J/psi production at CLEO

Polarizations of the prompt $J/ψ$'s produced in the $e^+e^-$ annihilation at CLEO energy ($\sqrt{s} = 10.58$ GeV) are considered in the framework of NRQCD factorization formalism. We find that the $J/ψ$ polarization has strong dependence on the production mechanism. At CLEO energy, the most dominant $J/ψ$ production mechanism in the most phase space is the color-singlet mechanism, $e^+e^- \to J/ψ+gg$, for which $J/ψ$'s are highly longitudinally polarized. On the other hand, the dominant $J/ψ$ production mechanism at the upper end point of $J/ψ$ energy distribution is the color-octet process, $e^+e^- \to (c\bar{c})^{(8)} +g$, for which $J/ψ$'s are almost unpolarized. Thus, the measurement of the polarization of the end point $J/ψ$'s can give another test of color-octet mechanism, and constraint on the NRQCD matrix elements.

hep-ph↗

arXiv1998

Analytic reduction of transition amplitudes in radiative electroweak processes

It is shown that the transition amplitudes of radiative electroweak processes like $e^-e^+ \to ν_e \olν_e \ga$, $\ga e^- \to ν_e \olν_e e^-$, and $ν_e e^- \to ν_e e^- \ga$ can be reduced and factorized into simpler forms in the Standard Model. This method can be used in reducing many calculations of complicated radiative electroweak processes in general.

hep-ph↗

arXiv1997

Color-octet mechanism and J/psi polarization at LEP

Polarized heavy quarkonium productions in $Z^0$ decays are considered. We find that polarizations of the produced quarkonia are independent of that of the parent Z^0 provided that one considers the energy distribution or the total production rate. Produced J/psi's via the color-octet and the color- singlet mechanisms are expected to be 19% and 29% longitudinally polarized, respectively. The energy dependence of eta_{1,8}(x)=\frac{dGamma_{1,8}^L}{dx} /\frac{dGamma_{1,8}}{d x} is very sensitive to the production mechanism, and therefore the measurement of η(x)_exp will be an independent probe of the color-octet mechanism.

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↗