120764517
QCD and jets in leptoproduction
Abstract The analogue for leptoproduction of the Sterman-Weinberg jet formula is derived. The 2-jet fraction is calculated in first order QCD and explicitly shown to be free of mass singularities. Approximations made in the derivation limit the phenomenological usefulness of the formula but, by studying the quark jet in isolation, a related formula of greater applicability is also obtained. Certain qualitative features of jet properties in perturbative QCD (notably x Bj and y dependence at fixed W ) are emphasized and contrasted with the fragmentation picture. Quark jets in leptoproduction are shown to be quantitatively different from quark jets in e + e − annihilation.
121312073
Gluon enhancements in charmed-meson decays
We address tests of nonspectator diagrams in charmed-meson decays. In particular, we explore the consequences of a model in which such diagrams are enhanced by the emission of a single gluon. For a lifetime ratio tau(D/sup +/)/tau(D/sup 0/)=5, we predict (i) tau(F/sup +/)/tau(D/sup +/) approx. = 0.6, (ii) an enhanced ..delta..S=0 rate for D/sup +/, (iii) a substantial multipion branching fraction for the F/sup +/, (iv) an F/sup +/ ..-->.. tau/sup +/..nu.. branching fraction of order 10 --20%, and (v) restrictive bounds on the D/sup 0/ ..-->.. K-bar/sup 0/..pi../sup 0/ mode.
119880793
Optimized perturbation theory in the Gross-Neveu model
119264999
Optimization of QCD perturbation theory: Results for Re+e− at fourth order
Abstract Physical quantities in QCD are independent of renormalization scheme (RS), but that exact invariance is spoiled by truncations of the perturbation series. “Optimization” corresponds to making the perturbative approximant, at any given order, locally invariant under small RS changes. A solution of the resulting optimization equations is presented. It allows an efficient algorithm for finding the optimized result. Example results for R e + e − = 3 ∑ q i 2 ( 1 + R ) to fourth order (NNNLO) are given that show nice convergence, even down to arbitrarily low energies. The Q = 0 “freezing” behavior, R = 0.3 ± 0.3 , found at third order is confirmed and made more precise; R = 0.2 ± 0.1 . Low-energy results in the MS ¯ scheme, by contrast, show the typical pathologies of a non-convergent asymptotic series.
119042764
Resolution of the lambda phi**4 puzzle and a 2-TeV Higgs boson
We argue that massless (lambda Phi^4)_4 is "trivial" without being entirely trivial. It has a non-trivial effective potential which leads to spontaneous symmetry breaking, but the particle excitations above the broken vacuum are non-interacting. The key to this picture is the realization that the constant background field (the mode with zero 4-momentum) renormalizes differently from the fluctuation field (the finite-momentum modes). This picture reconciles rigorous results and lattice calculations with one-loop and Gaussian-approximation analyses. Because of "triviality", these latter two methods should be effectively exact. Indeed, they yield the same renormalized effective potential and the same relation m_h^2 = 8 pi^2 v^2 between the particle mass and the physical vacuum expectation value. This relation predicts a Higgs mass m_h about 2 TeV in the standard model. The non-interacting nature of the scalar sector implies, by the equivalence theorem, that Higgs and gauge bosons interact only weakly, through their gauge and Yukawa couplings.
117188910
The renormalization‐scheme‐dependence problem and its solution
I explain, in ‘‘uncompromising’’ terms, the solution to the renormalization‐scheme‐dependence problem.
14308528
Mass dispersions from giant dipole resonances using the Balian–Vénéroni variational approach
The Balian–Veneroni variational approach has been implemented using a three-dimensional time-dependent Hartree–Fock (TDHF) code with realistic Skyrme interactions and used to investigate the mass dispersions from giant dipole resonances in 32S and 132Sn decaying through particle emission. The fluctuations obtained are shown to be quantitatively larger than the standard TDHF results.
15719604
Do Skyrme forces that fit nuclear matter work well in finite nuclei
A short list of Skyrme force parameterizations, recently found to have passed a series of constraints relating to nuclear matter properties is analyzed for their ability to reproduce data in ﬁnite nuclei. We analyse binding energies, isotope shifts, neutron skin thicknesses and ﬁssion barriers. We ﬁnd that the subset of forces have no common ability to reproduce(or otherwise)properties of ﬁnite nuclei, despite passing the extensive range of nuclear matter constraints.
120382191
Densities of superheavy nuclei at closed shells
We employed the Skynne-Hartree-Fock + BCS model to investigate the density distributions of even-even superheavy nuclei around the predicted rnagic numbers of Z = 114, 120, 126 and N = 172, 184. The central depressions in densities are shown in the heaviest nuclei with Z <= 120 and N <= 178, which is due to high-j orbits occupied. However, densities become flatter when deformations occur. The superheavy nuclei with N = 180-188 and Z = 126 have no central depressions, due to that low-j orbits become occupied. Shell closures in the superheavy mass region are isospin dependent.
121521132
Nuclear Matter and Neutron Star Properties Calculated with a Separable Monopole Interaction
16803754
Self-consistent description of dysprosium isotopes in the doubly midshell region
Dy in the framework of density-dependent Hartree-Fockcalculations with BCS pairing correlations. Further deformed Hartree-Fock with angular-momentum projectionand band-mixing calculations explore the yrast spectra of the nuclides approaching the neutron midshell.Predictions of high-K states in the doubly midshell nucleus