Baryon number generation in grand unified theories

Grand unified models of elementary particle interactions suggest that there was an early epoch during the Big Bang while the temperature was slightly less than the Planck temperature, during which no known interactions were in thermal equilibrium. This epoch was probably followed by a brief period during which baryon number violating forces were in equilibrium and could have annihilated any previously existing net baryon number. As these forces dropped out of equilibrium, a CP violating component could have generated the observed baryon to entropy ratio of O(10⁻⁹).     

Is the universe expanding?

It is shown that spherically symmetric static general relativistic cosmological space-times can reproduce the same cosmological observations as the currently favored Friedmann-Robertson-Walker universes, if the usual assumptions are made about the local physical laws determining the behavior of matter, provided that the universe is inhomogeneous and our galaxy is situated close to one of its centers. Only (i) unverifiable a priori assumptions, (ii) detailed physical and astrophysical arguments, or (iii) observation of the time variation of cosmological quantities can lead us to conclude that the universe we live in is not such a static space-time.This essay was awarded the second prize for 1977 by the Gravity Research Foundation.     

Observation of diffraction excitation in pp → (pπ+π−)+X at the CERN-ISR and tests of limiting fragmentation

In a single-arm magnetic spectrometer experiment at the CERN Intersecting Storage Rings (ISR), a prominent diffractive enhancement is observed for inclusive production of (pπ⁺π^?) systems near x ～ 1 at √s = 53 and 35 GeV. In testing limiting fragmentation and scaling for this system, inclusive pπ⁺π^? diffractive excitation into a fixed invariant mass range is found to possess a cross-section independent of s to within (3 ± 5)%. The main component in the (pπ⁺π^?) system is Δ(1236)π, with a charge structure compatible with the break-up of an isotopic spin $\text{1}\text{2}$ system.     

Overlayer disregistry: Transform simulations of leed patterns

Optical transforms have been utilized to study characteristic low-energy electron diffraction features from overlayers on six-fold substrates, including .(i) commensurate √3 overlayers reduced to 85%, (ii) orientationally incommensurate √3 structures, (iii) coincidence-lattices and (iv) several cases of one- and two-dimensional sinusoidal periodic lattice distortions. Readily identifiable, distinguishing differences are apparent among these classes of overlayer disregistry. The one prominent and distinctive feature common to periodic distortions on six-fold substrates is the absence of satellite beams around the 00 reflection for which a kinematical diffraction analysis is also given. The analogs graphically illustrate the possibility of misinterpretations.     

Primordial supersymmetric inflation

We discuss the motivations for reconsidering cosmological inflation in supersymmetric theories as contrasted with conventional GUTs. Radiative corrections to the effective potential can be made arbitrarily small in supersymmetric GUTs, removing some of the obstacles to inflation. We analyze general renormalizable potentials at the tree level and show that the required fine-tuning of parameters becomes less acute if inflation takes place before the grand unified phase transition, a hypothesis we term primordial inflation. We show how the grand unified monopole problem can be solved in supersymmetric GUTs embodying primordial inflation.     

Ionization energies and optical spectra of 5d-metal hexafluorides as calculated in the Dirac-Slater model

A relativistic self-consistent Dirac-Slater model has been used in a study of the electronic structure of 5d-metal hexafluorides. Experimental absorption spectra have been compared with calculated energies obtained as one-electron energy differences. The calculated “crystal field” splitting between the relativistic analog oft _2g ande _g levels, as well as spinorbit splitting of thet _2g level, has been found to be in good agreement with experimental data. Ionization energies which agree well with available spectra have been calculated using a transition state procedure. From a Mulliken population analysis of the molecular levels and ground state charge densities the validity of the classical crystal-field model is discussed.     

Low-energy 3He+ ion scattering spectroscopy studies of D2 adsorption on W(211)

Direct physical evidence for occupation of a trough site by the β₂ state of deuterium adsorbed on W(211) has been obtained by angle-resolved ³He⁺/D(ads) ion-scattering spectroscopy (ISS) in combination with LEED/Auger. The W(211) surface is composed of close-packed 〈111〉 rows of W atoms separated by a wide channel. Previous thermal desorption studies have shown two clearly resolved hydrogen states: β₁ desorbing with a temperature maximum of ca. 60°C, and β₂ at ca. 400°C. Analyses of flash desorption, work-function, adsorption kinetics, stoichiometry and mixed adsorption further indicated that the more tightly bound β₂ form occupies a deep-trough position. In the present study, ISS polar-angle profiles were taken at an incident energy of 306 eV. With only the β₂ state populated, a ³He⁺ beam parallel to the close-packed 〈111〉 rows was found to scatter from D(ads) with a cutoff angle close to grazing incidence while for the perpendicular direction D(ads) scattering is observed only for angles greater than 18° away from grazing incidence. These measurements are consistent with the corrugated W(211) geometry and with the proposed β₂-D trough-site model.     

The string coupling accelerates the expansion of the universed

Generic cosmological models in non-critical string theory have a time-dependent dilaton background at a late epoch. The cosmological deceleration parameter q ₀ is given by the square of the string coupling, g _s ², up to a negative sign. Hence the expansion of the Universe must accelerate eventually, and the observed value of q ₀ corresponds to g _s ² ∼ 0.6. In this scenario, the string coupling is asymptotically free at large times, but its present rate of change is imperceptibly small. First Award in the 2005 Essay Competition of the Gravity Research Foundation. - Ed.