Two-photon exchange model for production of neutral meson pairs in e+e- annihilation

A vector-dominance two-photon exchange model is proposed to explain the recently observed production of $\rho^0\rho^0$ and $\rho^0\phi$ pairs in $e^+e^-$ annihilation at 10.58 GeV with the BaBar detector. All the observed features of the data --angular and decay distributions, rates-- are in agreement with the model. Predictions are made for yet-unobserved final states.Comment: 7 pages, 2 figures, 1 tabl

Quarkonium Decays and Light Quark Masses

The $SU(3)$-violating decays \Phi^{2S} \goto \Phi^{1S} X, where $X = \pi^0$ or $\eta$ and $\Phi = J/\psi$ or $\Upsilon$ have been recently proposed as a means of probing the light quark masses beyond leading order in chiral perturbation theory. We argue that this analysis is incorrect, even in the heavy quark limit. We show that these decays are governed by an infinite number of matrix elements which are not suppressed by any small parameter, and which cannot be computed with our present understanding of QCD. Furthermore, for sufficiently heavy quarks, we show that the decay amplitudes can be organized into a twist expansion, and that the contributions considered in the above proposal are subleading in this expansion. We also explain how these decays nonetheless give a constraint on the light quark masses valid at {\it leading order} in the chiral expansion. The decays \Phi^{1S} \goto \eta\gamma and \Phi^{2S} \goto \Phi^{1S} \pi\pi also have contributions from infinitely many operators, contrary to claims in the literature.Comment: 8 pages, LBL-33946, UCB-PTH-93/1

One-loop counterterms in the Yang-Mills theory with gauge invariant ghost field Lagrangian

One-loop calculations of renormalization constants in the model with gauge invariant ghost field Lagrangian are performed. It is shown that the model is asymptotically free and the renormalization constants satisfy the same equation as in the ordinary Yang-Mills theory.Comment: 11 pages, 6 figure

Mixing Renormalization for Scalar Fields

We consider the renormalization of theories with many scalar fields. We discuss at the one-loop level some simple, non-gauge models with an arbitrary number of scalars and fermions both in mass-shell and MS schemes. In MS scheme we give a detailed qualitative analysis of the RG flow of dimensionless couplings in flavor space.Comment: 32 pages, LaTeX2e, AmsLaTeX, minor typos correcte

Impact parameter dependence of heavy ion e+ e- pair production to all orders in Z alpha

The heavy ion probability for continuum e+ e- pair production has been calculated to all orders in Z alpha as a function of impact parameter. The formula resulting from an exact solution of the semiclassical Dirac equation in the ultrarelativistic limit is evaluated numerically. In a calculation of gamma = 100 colliding Au ions the probability of e+ e- pair production is reduced from the perturbation theory result throughout the impact parameter range.Comment: 20 pages, latex, revtex, 6 eps figures. Revised Phys. Rev. C version with minor additions, one figure added, and added reference

Dynamical Hartree-Fock-Bogoliubov Theory of Vortices in Bose-Einstein Condensates at Finite Temperature

We present a method utilizing the continuity equation for the condensate density to make predictions of the precessional frequency of single off-axis vortices and of vortex arrays in Bose-Einstein condensates at finite temperature. We also present an orthogonalized Hartree-Fock-Bogoliubov (HFB) formalism. We solve the continuity equation for the condensate density self-consistently with the orthogonalized HFB equations, and find stationary solutions in the frame rotating at this frequency. As an example of the utility of this formalism we obtain time-independent solutions for quasi-two-dimensional rotating systems in the co-rotating frame. We compare these results with time-dependent predictions where we simulate stirring of the condensate.Comment: 13 pages, 11 figures, 1 tabl

Parton showers as sources of energy-momentum deposition in the QGP and their implication for shockwave formation at RHIC and at the LHC

We derive the distribution of energy and momentum transmitted from a primary fast parton and its medium-induced bremsstrahlung gluons to a thermalized quark-gluon plasma. Our calculation takes into account the important and thus far neglected effects of quantum interference between the resulting color currents. We use our result to obtain the rate at which energy is absorbed by the medium as a function of time and find that the rate is modified by the quantum interference between the primary parton and secondary gluons. This Landau-Pomeranchuk-Migdal type interference persists for time scales relevant to heavy ion phenomenology. We further couple the newly derived source of energy and momentum deposition to linearized hydrodynamics to obtain the bulk medium response to realistic parton propagation and splitting in the quark-gluon plasma. We find that because of the characteristic large angle in-medium gluon emission and the multiple sources of energy deposition in a parton shower, formation of well defined Mach cones by energetic jets in heavy ion reactions is not likely.Comment: 8 pages, 4 figure

Diagrammatic quantum field formalism for localized electrons

We introduce a diagrammatic quantum field formalism for the evaluation of normalized expectation values of operators, and suitable for systems with localized electrons. It is used to develop a convergent series expansion for the energy in powers of overlap integrals of single-particle orbitals. This method gives intuitive and practical rules for writing down the expansion to arbitrary order of overlap, and can be applied to any spin configuration and to any dimension. Its applicability for systems with well localized electrons has been illustrated with examples, including the two-dimensional Wigner crystal and spin-singlets in the low-density electron gas.Comment: 13 pages, 0 figure

Vector boson mass generation without new fields

Previously a model of only vector fields with a local U(2) symmetry was introduced for which one finds a massless U(1) photon and a massive SU(2) vector boson in the lattice regularization. Here it is shown that quantization of its classical continuum action leads to perturbative renormalization difficulties. But, non-perturbative Monte Carlo calculations favor the existence of a quantum continuum limit.Comment: 4 pages, 3 figures, 2 tables. Revised after referee reports. One error eliminate