A Non-Perturbative, Finite Particle Number Approach to Relativistic Scattering Theory

We present integral equations for the scattering amplitudes of three scalar particles, using the Faddeev channel decomposition, which can be readily extended to any finite number of particles of any helicity. The solution of these equations, which have been demonstrated to be calculable, provide a non-perturbative way of obtaining relativistic scattering amplitudes for any finite number of particles that are Lorentz invariant, unitary, cluster decomposable and reduce unambiguously in the non-relativistic limit to the non-relativistic Faddeev equations. The aim of this program is to develop equations which explicitly depend upon physically observable input variables, and do not require renormalization or dressing of these parameters to connect them to the boundary states

CMB Fluctuation Amplitude from Dark Energy Partitions

It is assumed that the dark energy observed today is frozen as a result of a phase transition involving the source of that energy. Postulating that the dark energy de-coherence which results from this phase transition drives statistical variations in the energy density specifies a class of cosmological models in which the cosmic microwave background (CMB) fluctuation amplitude at last scattering is approximately $10^{-5}$.Comment: 7 Pages, Poster presented at Texas@Stanford conference, Dec. 2004, minor clarification

Construction of Non-Perturbative, Unitary Particle-Antiparticle Amplitudes for Finite Particle Number Scattering Formalisms

Starting from a unitary, Lorentz invariant two-particle scattering amplitude , we show how to use an identification and replacement process to construct a unique, unitary particle-antiparticle amplitude. This process differs from conventional on-shell Mandelstam s,t,u crossing in that the input and constructed amplitudes can be off-diagonal and off-energy shell. Further, amplitudes are constructed using the invariant parameters which are appropriate to use as driving terms in the multi-particle, multichannel non-perturbative, cluster decomposable, relativistic scattering equations of the Faddeev-type integral equations recently presented by Alfred, Kwizera, Lindesay and Noyes. It is therefore anticipated that when so employed, the resulting multi-channel solutions will also be unitary. The process preserves the usual particle-antiparticle symmetries. To illustrate this process, we construct a J=0 scattering length model chosen for simplicity. We also exhibit a class of physical models which contain a finite quantum mass parameter and are Lorentz invariant. These are constructed to reduce in the appropriate limits, and with the proper choice of value and sign of the interaction parameter, to the asymptotic solution of the non-relativistic Coulomb problem, including the forward scattering singularity, the essential singularity in the phase, and the Bohr bound-state spectrum

Three-neutron resonance trajectories for realistic interaction models

Three-neutron resonances are investigated using realistic nucleon-nucleon interaction models. The resonance pole trajectories are explored by first adding an additional interaction to artificially bind the three-neutron system and then gradually removing it. The pole positions for the three-neutron states up to J=5/2 are localized in the third energy quadrant-Im (E)<=0, Re (E)<=0-well before the additional interaction is removed. Our study shows that realistic nucleon-nucleon interaction models exclude any possible experimental signature of three-neutron resonances.Comment: 13 pages ; 8 figs ; 5 table

Dynamics of Magnetic Flux Elements in the Solar Photosphere

The interaction of magnetic fields and convection is investigated in the context of the coronal heating problem. We study the motions of photospheric magnetic elements using filtergrams obtained at the Swedish Vacuum Solar Telescope at La Palma. We use potential-field modeling to extrapolate the magnetic and velocity fields to larger height. We find that the velocity in the chromosphere can be locally enhanced at the separatrix surfaces between neighboring flux tubes. The predicted velocities are several km/s, significantly larger than those of the photospheric flux tubes, which may have important implications for coronal heating. sComment: submitted to ApJ, 21 pages, 10 figure

Super-recognizers: From the lab to the world and back again

The recent discovery of individuals with superior face processing ability has sparked considerable interest amongst cognitive scientists and practitioners alike. These ‘Super‐recognizers’ (SRs) offer clues to the underlying processes responsible for high levels of face processing ability. It has been claimed that they can help make societies safer and fairer by improving accuracy of facial identity processing in real‐world tasks, for example when identifying suspects from Closed Circuit Television or performing security‐critical identity verification tasks. Here, we argue that the current understanding of superior face processing does not justify widespread interest in SR deployment: There are relatively few studies of SRs and no evidence that high accuracy on laboratory‐based tests translates directly to operational deployment. Using simulated data, we show that modest accuracy benefits can be expected from deploying SRs on the basis of ideally calibrated laboratory tests. Attaining more substantial benefits will require greater levels of communication and collaboration between psychologists and practitioners. We propose that translational and reverse‐translational approaches to knowledge development are critical to advance current understanding and to enable optimal deployment of SRs in society. Finally, we outline knowledge gaps that this approach can help address

Energy Dependence of the Near-Threshold Total Cross-Section for the pp --> pp eta' Reaction

Total cross sections for the pp --> pp eta' reaction have been measured in the excess energy range from Q = 1.53 MeV to Q = 23.64 MeV. The experiment has been performed at the internal installation COSY-11 using a stochastically cooled proton beam of the COoler SYnchrotron COSY and a hydrogen cluster target. The determined energy dependence of the total cross section weakens the hypothesis of the S-wave repulsive interaction between the eta' meson and the proton. New data agree well with predictions based on the phase-space distribution modified by the proton-proton final-state-interaction (FSI) only.Comment: 12 pages, 1 table, 4 figure