Emergent Photons and Gravitons:The Problem of Vacuum Structure

We discuss vacuum condensates associated with emergent QED and with torsion, as well as the possible role of the Kodama wave function in quantum cosmology.Comment: Talk presented at the Fifth Meeting on CPT and Lorentz Symmetry, University of Indiana, June 28-July 2, 201

Intersections 2000: What's New in Hadron Physics

Hadron physics is that part of QCD dealing with hadron structure and vacuum structure, almost all of which is nonperturbative in nature. Some of the open problems in this field are outlined. We argue that hadron physics is a distinct subfield, no longer within particle physics, and not at all the same as classical nuclear physics. We believe that it needs to be better organized, and that a first step in doing so might be to establish hadron physics as a new division within the American Physical Society.Comment: Invited Talk at 7th Conference on the Intersections of Particle and Nuclear Physics, Quebec City, Quebec, Canada, May 22-28, 200

Hybrid Dirac Fields

Hybrid Dirac fields are fields that are general superpositions of the annihilation and creation parts of four Dirac spin 1/2 fields, $\psi^{(\pm)}(x;\pm m)$, whose annihilation and creation parts obey the Dirac equation with mass $m$ and mass $-m$. We discuss a specific case of such fields, which has been called ``homeotic.'' We show for this case, as is true in general for hybrid Dirac fields (except the ordinary fields whose annihilation and creation parts both obey one or the other Dirac equation), that (1) any interacting theory violates both Lorentz covariance and causality, (2) the discrete transformations $\mathcal{C}$, and $\mathcal{CPT}$ map the pair $\psi_h(x)$ and $\bar{\psi}_h(x)$ into fields that are not linear combinations of this pair, and (3) the chiral projections of $\psi_h(x)$ are sums of the usual Dirac fields with masses $m$ and $-m$; on these chiral projections $\mathcal{C}$, and $\mathcal{CPT}$ are defined in the usual way, their interactions do not violate $\mathcal{CPT}$, and interactions of chiral projections are Lorentz covariant and causal. In short, the main claims concerning ``homeotic'' fields are incorrect.Comment: 10 pages, acknowledgement added, to appear in Phys. Lett.

Future Directions for QCD

New directions for exploring QCD at future high-energy colliders are sketched. These include jets within jets, BFKL dynamics, soft and hard diffraction, searches for disoriented chiral condensate, and doing a better job on minimum bias physics. The new experimental opportunities include electron-ion collisions at HERA, a new collider detector at the C0 region of the TeVatron, and the FELIX initiative at the LHC.Comment: Latex, 6 pages, to be published in the proceedings of the 1996 DPF/DPB Summer Study of New Directions for High Energy Physics, Snowmass, CO, June 25-July 12, 199

Rapidity Gaps in Deep Inelastic Scattering

A simple semiquantitative picture of diffractive electroproduction is described. Although the diffractive component of $F_2$ is approximately independent of $Q^2$ and $W^2$, this mechanism is "soft," i.e. it depends upon large-distance physics and is not readily describable within perturbative QCD.Comment: LaTex 14 pages, 3 figures. To obtain a copy, send e-mail to [email protected]

Standard Model Parameters and the Cosmological Constant

Simple functional relations amongst standard model couplings, including gravitional, are conjectured. Possible implications for cosmology and future theory are discussed.Comment: submitted to Physical Review

Geometry of Multihadron Production

Summary talk given at the 24th International Symposium on Multiparticle Dynamics, Italy, September 1994 -- This summary talk only reviews a small sample of topics featured at this symposium: 1. Introduction 2. The Geometry and Geography of Phase space 3. Space-Time Geometry and HBT 4. Multiplicities, Intermittency, Correlations 5. Disoriented Chiral Condensate 6. Deep Inelastic Scattering at HERA 7. Other ContributionsComment: 18 pages, 4 figures, uuencode

Probability in relativistic quantum mechanics and foliation of spacetime

The conserved probability densities (attributed to the conserved currents derived from relativistic wave equations) should be non-negative and the integral of them over an entire hypersurface should be equal to one. To satisfy these requirements in a covariant manner, the foliation of spacetime must be such that each integral curve of the current crosses each hypersurface of the foliation once and only once. In some cases, it is necessary to use hypersurfaces that are not spacelike everywhere. The generalization to the many-particle case is also possible.Comment: 9 pages, 3 figures, revised, new references, to appear in Int. J. Mod. Phys.

Emergence of Coherent Long Wavelength Oscillations After a Quench: Application to QCD

To model the dynamics of the chiral order parameter in a far from equilibrium phase transition, we consider quenching in the O(4) linear sigma model. We argue, and present numerical evidence, that in the period immediately following the quench long wavelength modes of the pion field are amplified. This results in large regions of coherent pion oscillations, and could lead to dramatic phenomenological consequences in heavy ion collisions.Comment: 18 pages, 4 figures included (uuencoded and compressed); uses phyzzx; PUPT-1389, IASSNS-HEP-93/1