arXiv subjects
Publications and source records attributed to Taekoon Lee.
A general model is proposed for time-varying coupling constants in field theory, assuming the ultraviolet cutoff is a varying entity in the expanding universe. It is assumed that the cutoff depends on the scale factor of the universe and all bare couplings remain constant. This leads to varying renormalized coupling constants that evolve in proportion to the Hubble parameter. The evolution of the standard model constants is discussed.
The scattering of photons of x-ray energy off a Coulomb field in very forward scattering region may be thought as the refraction effect due to the Coulomb field. The cross section of the scattering can be computed from the photon bending angle obtained in geometrical optics. Its dependence on the fine structure constant is nonanalytic and softer than would the box diagrams of Delbruck scattering suggest. The refractive scattering is a nonlocal effect occurring over the distance scale of the impact parameter, and therefore may not be described by the single-box diagrams. We suggest that the scattering cross section is a consequence of the sum of the asymptotic series of the multi-box diagrams.
Concerning the trace anomaly in field theory a nonvanishing vacuum energy breaks the scale symmetry as well, in addition to the usual beta function dependent term, requiring a unit operator in the trace anomaly. This additional term is also necessary in quantum chromodynamics (QCD) to cancel the inherent ambiguity in the gluon condensate. The inseparability of the gluon condensate effect from the perturbative contribution to the vacuum energy renders it impossible to isolate the gluon condensate effect on the cosmological constant.
Photons traveling in a background electromagnetic field may bend via the vacuum polarization effect with the background field. The bending in a Coulomb field by a heavy nucleus is small even at a large atomic number, rendering it difficult to detect experimentally. As an amplifying mechanism of the effect we consider the bending of light traveling in a chamber of Coulomb gas. The Gaussian nature of the bending in the gas increases the total bending angle in proportion to the square root of the photon travel distance. The enhancement can be orders of magnitude over the bending by a single nucleus at a small impact parameter, which may help experimental observation of the Coulombic bending.
The perturbative contribution in the average plaquette is subtracted using Borel summation and the remnant of the plaquette is shown to scale as a dim-4 condensate. A critical review is presented of the renormalon subtraction scheme that claimed a dim-2 condensate. The extracted gluon condensate is compared with the latest result employing high order (35-loop) calculation in the stochastic perturbation theory.
An ansatz is proposed for the flavor dependence of the normalization constant for the first IR renormalon in heavy quark pole mass.
We consider the velocity shift of light in presence of radiation emitted by a black body. Within geometric optics formalism we calculate the bending angle of a light ray when there is a gradient in the energy density. We model the bending for two simplified cases. The bending angle is proportional to the inverse square power of the impact parameter ($\propto 1/b^2$) when the dilution of energy density is spherically symmetric. The bending angle is inversely proportional to the impact parameter ($\propto 1/b$) when the energy density dilutes cylindrically. Assuming that a neutron star is an isothermal black body, we estimate the order of magnitude for such bending angle and compare it with the bending angle by magnetic field.
In a series of articles it was recently claimed that the quantum chromodynamic (QCD) condensates are not the properties of the vacuum but of the hadrons and are confined inside them. We point out that this claim is incompatible with the chiral Lagrangian and Bose-Einstein statistics of the Goldstone bosons (pions) in chiral limit and conclude that the quark condensate must be the property of the QCD vacuum.
The universality of vacuum condensate can be exploited to relate the infrared renormalon caused large order behaviors of different processes. As an application the normalization constant of the large order behavior of the average plaquette is estimated using the Adler function.
We calculate the bending angles of light under the strong electric and magnetic fields by a charged black hole and a magnetized neutron star according to the nonlinear electrodynamics of Euler-Heisenberg interaction. The bending angle of light by the electric field of charged black hole is computed from geometric optics and a general formula is derived for light bending valid for any orientation of the magnetic dipole. The astronomical significance of the light bending by magnetic field of a neutron star is discussed.
The nonlinear Euler-Heisenberg interaction bends light toward an electric charge. The bending angle and trajectory of light in a Coulombic field are computed in geometric optics.
A Borel resummation scheme of subtracting the perturbative contribution from the average plaquette is proposed using the bilocal expansion of Borel transform. It is shown that the remnant of the average plaquette, after subtraction of the perturbative contribution, scales as a dim-4 condensate. A critical review of the existing procedure of renormalon subtraction is presented.
In relativistic potential model of heavy-light mesons it is essential to incorporate the chiral radiative corrections before comparing the model predictions with data. Once the radiative corrections are taken into account the potential model can explain the unusual mass spectra and absence of the spin orbit-inversion in P-wave states.
We show that the absence of spin-orbit inversions in heavy-light mesons can be explained by the chiral radiative corrections in potential model. A new potential model estimate is given of the masses for P-wave bottom mesons.
The vacuum energy density of the massive Schwinger model is shown to be not power expandable in the fermion mass.
The bilocal expansion of Borel transform provides an efficient way of Borel resummation with low order perturbations in QCD. Its applications to the heavy quark pole mass, static potential, and lattice calculation are reviewed.
We show that one loop chiral corrections for heavy-light mesons in potential model can explain the small mass of D_s(2317) as well as the small mass gap between D_s(2317) and D(2308).
The Borel summation technique of infrared renormalons is applied to the lattice determination of heavy quark mass. With Borel summation a physical heavy quark pole mass and binding energy of a heavy-light meson can be defined in a rigorous and calculable manner. A notable feature of the Borel summation, compared to the usual perturbative cancellation of IR renormalons, is an automatic scale separation. The two approaches of handling renormalon divergence are compared in the B-meson as well as in an (imaginary) heavy-light meson with a mass much larger than the inverse of the lattice spacing.