2,871 research outputs found
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
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 is approximately
independent of and , 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]
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.
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
Spontaneous breakdown of Lorentz symmetry in scalar QED with higher order derivatives
Scalar QED is studied with higher order derivatives for the scalar field
kinetic energy. A local potential is generated for the gauge field due to the
covariant derivatives and the vacuum with non-vanishing expectation value for
the scalar field and the vector potential is constructed in the leading order
saddle point expansion. This vacuum breaks the global gauge and Lorentz
symmetry spontaneously. The unitarity of time evolution is assured in the
physical, positive norm subspace and the linearized equations of motion are
calculated. Goldstone theorem always keeps the radiation field massless. A
particular model is constructed where the the full set of standard Maxwell
equations is recovered on the tree level thereby relegating the effects of
broken Lorentz symmetry to the level of radiative corrections.Comment: 14 pages, to appear in Phys. Rev.
Cluster Structure of Disoriented Chiral Condensates in Rapidity Distribution
We study the creation of disoriented chiral condensates with some initial
boundary conditions that may be expected in the relativistic heavy ion
collisions. The equations of motion in the linear -model are solved
numerically with and without a Lorentz-boost invariance. We suggest that a
distinct cluster structure of coherent pion production in the rapidity
distribution may emerge due to a quench and may be observed in experiments.Comment: 10 pages in LaTex, 2 uuencoded ps figures, LBL-3493
Finite cosmology and a CMB cold spot
The standard cosmological model posits a spatially flat universe of infinite
extent. However, no observation, even in principle, could verify that the
matter extends to infinity. In this work we model the universe as a finite
spherical ball of dust and dark energy, and obtain a lower limit estimate of
its mass and present size: the mass is at least 5 x 10^23 solar masses and the
present radius is at least 50 Gly. If we are not too far from the dust-ball
edge we might expect to see a cold spot in the cosmic microwave background, and
there might be suppression of the low multipoles in the angular power spectrum.
Thus the model may be testable, at least in principle. We also obtain and
discuss the geometry exterior to the dust ball; it is Schwarzschild-de Sitter
with a naked singularity, and provides an interesting picture of cosmogenesis.
Finally we briefly sketch how radiation and inflation eras may be incorporated
into the model.Comment: 20 pages, 12 figure
The Future of Particle Physics
After a very brief review of twentieth century elementary particle physics,
prospects for the next century are discussed. First and most important are
technological limits of opportunities; next, the future experimental program,
and finally the status of the theory, in particular its limitations as well as
its opportunities.Comment: Invited talk given at the International Conference on Fundamental
Sciences: Mathematics and Theoretical Physics, Singapore, 13-17 March 200
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