Isoscalar-isovector mass splittings in excited mesons

Mass splittings between the isovector and isoscalar members of meson nonets arise in part from hadronic loop diagrams which violate the Okubo-Zweig-Iizuka rule. Using a model for these loop processes which works qualitatively well in the established nonets, I tabulate predictions for the splittings and associated isoscalar mixing angles in the remaining nonets below about 2.5 GeV, and explain some of their systematic features. The results for excited vector mesons compare favorably with experiment.Comment: 8 RevTeX pages, including 1 LaTeX figure. CMU-HEP93-23/DOE-ER-40682-4

Glueball Interpretation of ξ\xi(2230)

On the basis of the results of $\xi(2230)\rightarrow\pi^{+}\pi^{-}, p\bar{p}$ and $K\bar{K}$, measured by the BES Collaboration in radiative J/$\psi$ decays, combined with the upper limit of Br($\xi\rightarrow p\bar{p}$)Br($\xi\rightarrow K\bar{K}$), measured by PS185 experiment, we argue that the distinctive properties of $\xi$(2230), the flavor-symmetric decays and the narrow partial decay widths to $\pi\pi$ and $K\bar{K}$ as well as its copious production in radiative J/$\psi$ decay, would strongly favor the glueball interpretation of $\xi$(2230).Comment: Latex file, no figure

Properties of the Strange Axial Mesons in the Relativized Quark Model

We studied properties of the strange axial mesons in the relativized quark model. We calculated the $K_1$ decay constant in the quark model and showed how it can be used to extract the $K_1 (^3P_1) - K_1 (^1P_1)$ mixing angle ($\theta_K$) from the weak decay $\tau \to K_1 \nu_\tau$. The ratio $BR(\tau \to \nu_\tau K_1 (1270))/BR(\tau\to \nu_\tau K_1(1400))$ is the most sensitive measurement and also the most reliable since the largest of the theoretical uncertainties factor out. However the current bounds extracted from the TPC/Two-Gamma collaboration measurements are rather weak: we typically obtain $-30^o \lesssim \theta_K \lesssim 50^o$ at 68\% C.L. We also calculated the strong OZI-allowed decays in the pseudoscalar emission model and the flux-tube breaking model and extracted a $^3P_1 - ^1P_1$ mixing angle of $\theta_K \simeq 45^o$. Our analysis also indicates that the heavy quark limit does not give a good description of the strange mesons.Comment: Revised version to be published in Phys. Rev. D. Minor changes. Latex file uses revtex version 3 and epsfig, 4 postcript figures are attached. The full postcript version with embedded figures is available at ftp://ftp.physics.carleton.ca/pub/theory/godfrey/ocipc9512.ps.

Nonresonant Semileptonic Heavy Quark Decay

In both the large N_c limit and the valence quark model, semileptonic decays are dominated by resonant final states. Using Bjorken's sum rule in an "unquenched" version of the quark model, I demonstrate that in the heavy quark limit nonresonant final states should also be produced at a significant rate. By calculating the individual strengths of a large number of exclusive two-body nonresonant channels, I show that the total rate for such processes is highly fragmented. I also describe some very substantial duality-violating suppression factors which reduce the inclusive nonresonant rate to a few percent of the total semileptonic rate for the finite quark masses of B decay, and comment on the importance of nonresonant decays as testing grounds for very basic ideas on the structure, strength, and significance of the quark-antiquark sea and on quark-hadron duality in QCD.Comment: 51 pages, 2 Postscript figure

Phase Transitions at Finite Temperature and Dimensional Reduction for Fermions and Bosons

In a recent Letter we discussed the fact that large-$N$ expansions and computer simulations indicate that the universality class of the finite temperature chiral symmetry restoration transition in the 3D Gross-Neveu model is mean field theory. This was seen to be a counterexample to the standard 'sigma model' scenario which predicts the 2D Ising model universality class. In this article we present more evidence, both theoretical and numerical, that this result is correct. We develop a physical picture for our results and discuss the width of the scaling region (Ginzburg criterion), $1/N$ corrections, and differences between the dynamics of BCS superconductors and Gross-Neveu models. Lattices as large as $12 \times 72^2$ are simulated for both the $N=12$ and $N=4$ cases and the numerical evidence for mean field scaling is quite compelling. We point out that the amplitude ratio for the model's susceptibility is a particulartly good observable for distinguishing between the dimensional reduction and the mean field scenerios, because this universal quantity differs by almost a factor of $20$ in the two cases. The simulations are done close to the critical point in both the symmetric and broken phases, and correlation lengths of order $10$ are measured. The critical indices $\beta_{mag}$ and $\delta$ also pick out mean field behavior. We trace the breakdown of the standard scenario (dimensional reduction and universality) to the composite character of the mesons in the model. We point out that our results should be generic for theories with dynamical symmetry breaking, such as Quantum Chromodynamics. We also simulated the $O(2)$ model on $8 \times 16^3$ lattices to establish that our methods give the results of dimensional reduction in purely bosonicComment: 47 pages, latex, 23 figures in one uuencoded fil

Understanding the nature of Ds(2317)D_s(2317) and Ds(2460)D_s(2460) through nonleptonic B Decays

We consider the nonleptonic B decays $B \to D^{(*)} D_s(2317)$ and $B \to D^{(*)} D_s(2460)$, involving the newly discovered $D_s(2317)$ and the $D_s(2460)$ states. We find that experiments indicate disagreement with model calculations of their properties and/or breakdown of the factorization assumption for these decays . We point out that decays involving $B_s$ mesons where the $D_s$ resonances can be produced via the weak decay of the $b$ quark can provide further information about the nature of these newly discovered states. We also propose a model to calculate the two body nonleptonic decays $B \to D^{(*)} D_s(2317)(D_s(2460))$, if the $D_s(2317)$ and $D_s(2460)$ are interpreted as $DK$ and $D^*K$ molecules.Comment: 14 pages LaTeX; additional reference, notational corrections and minor clarifications of tex

The Partonic Content of h1(x)h_1(x) and $h_2(x)

A light-cone wavefunction interpretation is presented for the polarized distribution functions $h_1(x)$ and $h_2(x)$. All matrix elements for moments of these distributions are given in terms of overlap integrals between Fock state amplitudes of the target state. In a suitable spinor basis, $h_1(x)$ involves only diagonal matrix elements so can be interpreted as a density. Matrix elements of $h_2(x)$ connect Fock states differing by one gluon so that $h_2(x)$ has no simple interpretation as a density. Nevertheless, in the wavefunction decomposition, $h_2(x)$ is described through a compact set of elementary quark-gluon processes which are averaged over the target wavefunction.Comment: 16 pages, AZPH-TH 93-32, Latex, Phys. Rev D 49, 3187 (1994

Weak decays of doubly heavy hadrons

We explore the application and usefulness of the heavy quark symmetry to describe the weak decays of hadrons (mesons and baryons) containing two heavy quarks. Firstly, we address the internal dynamics of a heavy-heavy bound system with the help of estimates based on potential models, showing an approximate spin symmetry in the preasymptotic quark mass region including charmonium, bottonium and $B_c$ meson states. However, no asymptotic spin symmetry should hold in the infinite quark mass limit in contrast to singly heavy hadrons. Predictions on semileptonic and two-body nonleptonic decays of $B_c$ mesons are shown. Furthermore, the stemming flavor and spin symmetries from the interaction between the heavy and light components in hadrons (combining in a $\lq\lq$superflavor" symmetry) permit their classification in $meson$-type supermultiplets containing singly heavy mesons together with doubly heavy baryons, and $baryon$-type supermultiplets containing singly heavy baryons together with some exotic doubly heavy multiquark states (diquonia). Exploiting their well-defined transformation properties under the superflavor symmetry group, we get predictions on the widths for some semileptonic and two-body nonleptonic decays of baryons containing both $b$ and $c$ quarks.Comment: Latex, 26 pages, 2 figures available by FAX

Near-Threshold Production of omega Mesons in the pp -> pp omega Reaction

The total cross section for omega production in the pp -> pp omega reaction has been measured at five c.m. excess energies from 3.8 to 30 MeV. The energy dependence is easily understood in terms of a strong proton-proton final state interaction combined with a smearing over the width of the state. The ratio of near-threshold phi and omega production is consistent with the predictions of a one-pion-exchange model and the degree of violation of the OZI rule is similar to that found in the pi-p -> n omega/phi reactions.Comment: Report in LaTeX2e. 12 pages with 2 eps figure

The New Heavy Mesons: A Status Report

A survey of the experimental, phenomenological, and theoretical status of the new heavy mesons is presented. States discussed are the $B_c$, $h_c$, $\eta_c'$, $D_s(2317)$, $D_s(2460)$, X(3872), X(3940), Y(3940), Z(3930), and Y(4260). Quark models for spectra, strong decays, and hadronic interactions are reviewed and used to interpret the new states. New results for strong decay models, bound state decays, mesonic molecules, properties of the X(3872), and the chiral doublet model are also presented.Comment: 62 page, 40 figs, 16 tables. v3 corrects typos, adds references. Version to appear in Physics Report