arXiv subjects
Publications and source records attributed to Il-Tong Cheon.
By placing a ${}^{133}Cs$ $γ$-ray source embedded in a solid at the center of a platinum (gold) cylinder, we try to change the width of the 81-keV level. Our results show a narrowed energy level and, equivalently, a prolonged lifetime. With a 0.5-mm-thick, 5-cm-long, 2-mm-diameter platinum cylinder, we obtain a width narrower by $6.1 % $ at $4.2 \: K$.
A SU(2) effective lagrangian is extended to a $SU_{L}(3)\otimes SU_{R}(3)$ by including the vector and axial vector meson. With this effective lagrangian, electromagnetic form factors of charged pion and kaon are calculated. The pseudoscalar meson loops are taken into account. Good agreement with experimental data is obtained for those form factors. Decay widths of $ρ\to ππ$ and $ϕ\to K^{+}K^{-}$ are also calculated and shown to agree with experimental data very well.
Magnetic dipole and electric quadrupole moments of the mirror nuclei 8Li and 8B are analysed in the framework of the multiparticle shell model by using two approaches : i) the one-particle spectroscopic factors and ii) the one-particle fractional parentage coefficients. These two approaches are compared both each to other and with a microscopic multicluster model. The one-particle nucleon states are calculated taking into account the continuum by the method of the expansion of the Sturm - Liouville functions. The experimental magnetic and quadrupole moments of 8Li and 8Bare reproduced well by using fractional parentage coefficients technique. The root mean-square radii and the radial density distributions are obtained for these nuclei.
The kaon photoproduction is analyzed up to $E_γ^{\rm Lab}$=2.0 GeV by using an isobaric model based on effective Lagrangians and by taking a cross symmetry into account. Both {\it pseudovector} and {\it pseudoscalar} couplings for kaon-baryon-baryon (baryon spin=1/2) interactions are considered with form factors. A vector meson($K^*(890)$), an axial vector meson($K_1(1270)$), nucleon resonances($J\le5/2$), and hyperon resonances($J\le3/2$) are treated as participating particles. By determining unknown coupling constants through a systematic fitting of the differential cross section, the total cross section, the single polarization observable, and the radiative kaon capture branching ratio to their experimental data, we find out a simple model which reproduces all the experimental data well.
The recent TRIUMF experiment for $μ^- p \to n ν_μ γ$ gave a surprising result that the induced pseudoscalar coupling constant $g_P$ was larger than the value obtained from $μ^- p \to n ν_μ$ experiment as much as 44 %. Reexamining axial vector current on the gauge theory, we found an additional term to the matrix element of Beder and Fearing which was used to extract the $g_P$ value from the measured photon energy spectrum. This additional term, which is self gauge invariant, plays a key role in restoring the reliability of $g_P (- 0.88 m_μ^2) = 6.77 g_A (0)$. Comparison with conventional approaches is also presented.
The life-time of $^{133}Cs$ in the first excited state has been measured with the Mössbauer method by placing the absorber, CsCl, between two parallel flat plates and the gamma-ray source, Ba^*TiO_3, in the free space. The result is 9.37 \pm 0.19 ns, which is 49 percent larger than the standard value 6.27 \pm 0.02 ns.
The deuteron binding energy extracted from the reaction ${}^1H(n,γ){}^2H$ is reviewed with the exact relativistic formula, where the initial kinetic energy and the Doppler effect are taken into account. We find that the negligible initial kinetic energy of the neutron could cause a significant uncertainty which is beyond the errors available up to now. Therefore, we suggest an experiment which should include the detailed informations about the initial kinetic energy and the detection angle. It could reduce discrepancies among the recently reported values about the deuteron binding energy and pin down the uncertainty due to the Doppler broadening of $γ$ ray.
The recent TRIUMF experiment for $μ^- p \to n ν_μ γ$ gave a surprising result that the induced pseudoscalar coupling constant $g_P$ was larger than the value obtained from $μ^- p \to n ν_μ$ experiment as much as 44 %. Reexamining contribution of the axial vector current, we found an additional term to the matrix element of Beder and Fearing which was used to extract the $g_P$ value from the measured photon energy spectrum. This additional term plays a key role to restore the reliability of $g_P (- 0.88 m_μ^2) = 6.77 g_A (0)$.
The recent TRIUMF experiment for $μ^- p \to n ν_μ γ$ gave a surprising result that the induced pseudoscalar coupling constant $g_P$ was larger than the value obtained from $μ^- p \to n ν_μ$ experiment as much as 44 %. Reexamining contribution of the axial vector current in electromagnetic interaction, we found an additional term to the matrix element which was used to extract the $g_P$ value from the measured photon energy spectrum. This additional term, which plays a key role to restore the reliability of $g_P (- 0.88 m_μ^2) = 6.77 g_A (0)$, is shown to affect the $g_P$ quenching problems in nucleus.
We discussed the possibility that the charged axial currents of matter fields could be non-conserved in electromagnetic interaction at $O(e) $ order. It means that chiral symmetry is broken explicitly by electromagnetic interaction. This explicit symmetry breaking of chiral symmetry is shown to lead the mass differences between the charged and neutral particles of matter fields.
In the paper the Schrödinger equation for quasibound resonance state with complex energy is considered. The system of inhomogeneous differential equations is obtained for the real and imaginary parts of wave function. On the base of known solution of corresponding homogeneous equation, the inhomogeneus system is solved with help of iteration procedure. The single-particle neutron $2p$-state in the Woods - Saxon potential is analyzed for $^{13}C$ nucleus.
Sum of the time component of $Σ$ term and the induced pseudo scalar term in axial current is shown to be the t-channel pion pole in Born terms for pion electroproduction near threshold. We also show that this $Σ$ term represents the charged pseudo scalar quark density matrix elements in nucleon and manifests itself in the $L_0^+$ amplitude on this reaction.
When a hydrogen atom trapped in finite space formed by two parallel perfectly conducting plates, the transition rates can be modified. Life-time of the hydrogen $2P_{1/2}$-state is estimated to be shorter as much as $56.3ps $ with a separation distance of $b = 1.2 μm$ between two plates. Although the modification is dependent on position of the atom, the life-time can be shorten or lengthen by adjusting the separation distance even for the case that the atom is placed at the center between two plates.
Considering the stresses due to the vacuum fluctuation and the electric charge loaded over the surface of a spherical cavity, we estimate the maximum value of the charge. Since this value is independent of the cavity size and parameter free, it is regarded as the electric unit charge. Our result is $Q= 1.55\times 10^{-19}$ Coulomb which implies the relevant fine structure constant $α=1/145.90$.