7265145
Quark mixing and CP violation.
In view of the experimental indications that the top-quark mass may exceed the upper bound predicted by the Fritzsch ansatz for the quark mass matrices, we follow a phenomenological approach to find a modified form of the mass matrices to deal with quark mixing and {ital CP} violation in electroweak interactions. The essential feature of our mass matrices is that the diagonal elements corresponding to the light quarks {ital u}, {ital d}, and {ital s} are vanishingly small, while those corresponding to the heavy quarks {ital c}, {ital b}, and {ital t} are approximately equal to the observed values of their masses. By comparing our theoretical results for the Kobayashi-Maskawa mixing matrix elements with the experimental data, we obtain for the top-quark mass and the {ital CP}-violating phase the values {ital m}{sub {ital t}}{sup phys}{le}170 GeV and 91{degree}{le}{delta}{le}105{degree}.
6552264
Nonsingular potential model for heavy quarkonia.
A nonsingular potential model for heavy quarkonia is described which does not require recourse to an illegitimate perturbative treatment for the investigation of quarkonium spectra. Our overall results for the energy levels, the leptonic widths, and the E1 transition widths are in very good agreement with the experimental data for bb-bar and they are reasonably good for cc-bar. We also find that the confining part of the quarkonium potential is scalar-vector exchange rather than the currently favored scalar exchange.
122167852
MULTIPLE PHOTON PRODUCTION IN QUANTUM ELECTRODYNAMICS
Multiple production of photons in high-energy processes in quantum electrodynamics is investigated, and the electron-positron annihilation is specially discussed in detail. It is found that at very high energies in cosmic rays, multiple production of up to four or five observable photons can easily take place. But, the probability, according to quantum electrodynamics, for the multiple production of a larger number of observable photons is quite small.
120383870
Higgs model with ghost-field formalism
The Higgs model for the interaction of vector and scalar fields is treated by means of the ghost-field formalism, which preserves the unitarity of the scattering operator as well as simplifies the renormalization procedure. Our ghost-field formalism has some similarity to the ${R}_{\ensuremath{\xi}}$ formalism with $\ensuremath{\xi}=1$, but it does not require the introduction of the so-called gauge-compensating terms. Applications to the second-order self-energy of a scalar particle and to the fourth-order scattering of vector particles are discussed.
122156675
Relativistic Hadron Model with Intrinsic Mass Splittings
A simple mechanism for the $\mathrm{SU}(3)$-symmetry breaking in strong interactions is introduced by using the formalism of the multispinor field equations, which avoids the use of physical quarks but has resemblance to the quark model. The resulting treatment leads to the Gell-Mann-Okubo mass formula for baryons, but not for mesons. It yields approximate values of -19.5\ifmmode^\circ\else\textdegree\fi{} and 33\ifmmode^\circ\else\textdegree\fi{} for the $\ensuremath{\eta}\ensuremath{-}{\ensuremath{\eta}}^{\ensuremath{'}}$ and $\ensuremath{\varphi}\ensuremath{-}\ensuremath{\omega}$ mixing angles, respectively, and also provides a reasonable explanation for the intermultiplet meson mass formula $m_{K}^{}{}_{}{}^{2}\ensuremath{-}m_{\ensuremath{\pi}}^{}{}_{}{}^{2}=m_{{K}^{*}}^{}{}_{}{}^{2}\ensuremath{-}m_{\ensuremath{\rho}}^{}{}_{}{}^{2}$.
121663425
Quantum-chromodynamic potential model for light and heavy quarkonia
Our earlier treatment for the investigation of the cc-bar, bb-bar, and tt-bar spectra is extended to other p quarkonia with u, d, s, c, and b quarks. We find that it is possible to account fully for the observed ground-state hyperfine splittings of light as well as heavy quarkonia provided that the perturbative quantum-chromodynamic potential is supplemented not only by the nonperturbative confining potential but also by a nonperturbative annihilation potential which rapidly decreases with increase in the quark mass. We also give our predictions for the experimentally interesting bu-bar, bs-bar, and bc-bar systems with unknown mass splittings.
40514876
Hadronic correlation functions in the QCD plasma phase.
We present results for static hadronic correlation functions in the high-temperature phase of QCD with four flavors of dynamical quarks. We confirm chiral-symmetry restoration through the degeneracies of the spectrum of screening lengths. We also find that the screening lengths for the {rho} and {ital N} channels at {ital T}{approx gt}1.2{ital T}{sub {ital c}} are close to that in a free quark gas.
9625384
Clear evidence of redundant operators in Monte Carlo studies of the Ising model.
After reviewing the notion of redundant operators and the procedure for deriving them analytically for Ising systems, we present Monte Carlo renormalization-group data that clearly show their occurrence as eigenoperators in d = 2.
14017597
Bethe-Salpeter amplitudes and density correlations for mesons with Wilson fermions.
We present an investigation of various gauge-invariant definitions of the qq Bethe-Salpeter (BS) amplitude for mesons in lattice QCD, and compare them to the Coulomb and Landau gauge BS amplitudes. We show that the gauge-invariant BS amplitude is considerably broadened by the use of «fat» gauge links (constructed by smearing the links of the original lattice). A qualitative demonstration of the Lorentz contraction of the pion wave function at nonzero momentum is given. We also calculate density-density correlations and discuss the limitations in extracting the charge radius of the pion from these observables. Lastly, the polarization dependence of the BS amplitude for the ρ meson is exhibited, and we extract the relative admixture of l = 0 and l = 2 states showing that simple hydrogenlike wave functions provide a good fit
12293063
Detection of ultrahigh-energy radiation from Scorpius X-1: Ooty observations during 1984-1987.
A detailed study of showers arriving from the direction of Scorpius X-1 has shown strong evidence for emission of ultrahigh-energy radiation from Scorpius X-1 during the period 4 March-2 May 1986. 178 showers were observed in the source bin againat an expected background of 122.9. The chance probability for observing this excess has been estimated from simulations to be less than 10 -3 . The flux observed during this period was (6.4±1.6)×10 -12 cm -2 s -1 at energies >2.5×10 14 eV, corresponding to a luminosity of 2×10 35 ergs s -1 .
12480798
Critical behavior of the two-dimensional XY model.
We present detailed Monte Carlo results for the susceptibility {chi}, correlation length {xi}, and specific heat {ital C}{sub {ital v}} for the {ital XY} model. The simulations are done on 64{sup 2}, 128{sup 2}, 256{sup 2}, and 512{sup 2} lattices over the temperature range 0.98{le}{ital T}{le}1.43 corresponding to 2{lt}{xi}{lt}70. Fits to {chi} and {xi} data favor a Kosterlitz-Thouless (KT) singularity over a second-order transition; however, unconstrained four-parameter KT fits do not confirm the predicted values {nu}=0.5 and {eta}=0.25. Our best estimate, {ital T}{sub {ital c}}=0.894(5), is obtained using KT fits with {nu} fixed at 0.5. The exponent {eta} is calculated as a function of temperature in the spin-wave phase using Monte Carlo renormalization-group and finite-size-scaling methods. Both methods give consistent results and we find {eta}{approx}0.235 at {ital T}=0.894. We also present results for the behavior of vortex density across the transition and exhibit how the dilute-gas approximation breaks down.