120395006
ONE-GRAVITON EXCHANGE INTERACTION OF ELEMENTARY PARTICLES
The interaction of elementary particles of several different spins due to the exchange of a graviton is investigated. The exact one-graviton exchange potentials are obtained, and then simplified by making various approximations. The gravitational interaction is found to be independent of the spins of the particles, provided that the distance between them is large compared with their Compton wavelengths. I t is pointed out that the spin-dependent interaction terms, whose range is of the order of the Compton wavelength, may be of interest in the theory of gravitational collapse. I t is also shown that the gravitational particle-antiparticle interaction differs from the corresponding particle-particle interaction only by contact interaction terms.
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.
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 $m_{K}^{}{}_{}{}^{2}\ensuremath{-}m_{\ensuremath{\pi}}^{}{}_{}{}^{2}=m_{{K}^{*}}^{}{}_{}{}^{2}\ensuremath{-}m_{\ensuremath{\rho}}^{}{}_{}{}^{2}$.
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.
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.
122963652
Intrinsic density and energy dependence: Exchange effects in alpha-nucleus scattering
The exchange effect for the alpha-nucleus potential has been computed by folding in the density matrices with a finite range effective interaction. The ''effective'' exchange interaction is both density and energy dependent. The potential agrees closely with phenomenology.
123618858
An experimental system for detection of high energy cosmic gamma ray bursts
Abstract While bursts of cosmic gamma rays of energies 0.1–10 MeV can be detected and studied only with satellite-borne detectors, bursts of gamma rays at GeV energies can be detected using sensitive ground-based detectors. An experimental system to detect these high energy gamma ray bursts is being operated at the mountain altitude laboratory at Ootacamund, India. The design features and the experimental details related to this system are described.
118446008
The QCD Critical Point: Marching towards continuum
Abstract We present results of our simulations of QCD with two light dynamical quarks on a 32 3 × 8 lattice at a current quark mass tuned to have the Goldstone pion mass of about 230 MeV. Employing the Taylor expansion method we proposed earlier, we estimate the radius of convergence of the series for the baryonic susceptibility by using terms up to eighth order. Together with our earlier results, corresponding to the same physical parameters but on coarser lattices at respectively 1.33 times and twice the lattice cut-off ( a ), we were able to attempt a march towards the continuum limit.
14798493
Effects of momentum-dependent symmetry potential on heavy-ion collisions induced by neutron-rich nuclei
Abstract Using an isospin- and momentum-dependent transport model we study effects of the momentum-dependent symmetry potential on heavy-ion collisions induced by neutron-rich nuclei. It is found that symmetry potentials with and without the momentum-dependence but corresponding to the same density-dependent symmetry energy E sym ( ρ ) lead to significantly different predictions on several E sym ( ρ )-sensitive experimental observables especially for energetic nucleons. The momentum- and density-dependence of the symmetry potential have to be determined simultaneously in order to extract the E sym ( ρ ) accurately. The isospin asymmetry of midrapidity nucleons at high transverse momenta is particularly sensitive to the momentum-dependence of the symmetry potential. It is thus very useful for investigating accurately the equation of state of dense neutron-rich matter.
17004831
Taylor expansions in chemical potential
Properties of QCD at finite chemical potential (µ) are extracted using Taylor series expansions. The continuum limits of lattice results are presented. The result of expanding the free energy density, i.e., the pressure, to 6th order in the expansion is shown. The Taylor coefficients of the chiral condensate are also shown. Relations between various Taylor coefficients are demonstrated. All this information is utilised to remove various lattice artifacts from the determination of the Wroblewski parameter in strangeness production.