A5089740395- Particle physics theoretical and experimental studies
- Quantum Chromodynamics and Particle Interactions
- High-Energy Particle Collisions Research
- Neutrino Physics Research
- Nuclear physics research studies
- Astrophysics and Cosmic Phenomena
- Atomic and Molecular Physics
- Cold Atom Physics and Bose-Einstein Condensates
- Cosmology and Gravitation Theories
- Dark Matter and Cosmic Phenomena
- High-pressure geophysics and materials
- Superconducting Materials and Applications
- Pulsars and Gravitational Waves Research
- Nuclear Physics and Applications
- Particle accelerators and beam dynamics
- Quantum chaos and dynamical systems
- Atomic and Subatomic Physics Research
- Astro and Planetary Science
- Gamma-ray bursts and supernovae
- Crystallography and Radiation Phenomena
- Nuclear reactor physics and engineering
- Advanced NMR Techniques and Applications
- X-ray Spectroscopy and Fluorescence Analysis
- Music Technology and Sound Studies
- Musicology and Musical Analysis
Texas Tech University
2022
University of Manchester
2019
Vanderbilt University
2000-2015
Fisk University
2012-2013
Karlsruhe Institute of Technology
2008
Thomas Jefferson National Accelerator Facility
2001
Oak Ridge National Laboratory
1984-1995
Los Alamos National Laboratory
1979-1994
Texas A&M University
1982-1993
New Mexico State University
1985
This white paper addresses the hypothesis of light sterile neutrinos based on recent anomalies observed in neutrino experiments and latest astrophysical data.
Consideration is given to the approximation in which an arbitrary potential replaced by a separable potential. A method presented permits construction of rank-$N$ has property that resulting $T$ matrix exact on energy shell and half off at $N$ selected bound state and/or continuum energies. This yields correct vicinity on-shell points.
We find a solution to the static Chew-Low theory of pion-nucleon scattering, avoiding "one-meson approximation." Our basic equation is crossing symmetric and may be solved for phase shifts $\ensuremath{\delta}(p)$ by standard numerical techniques, upon specifying form factor $\ensuremath{\nu}(p)$ set inelasticities. With $\ensuremath{\nu}(p)=\mathrm{exp}(\frac{\ensuremath{-}{p}^{2}}{30})$ we reproduce experimental ${p}_{L}\ensuremath{\le}1.2 \frac{\mathrm{GeV}}{c}$ in (3,3) state; (1,3)...
The multiple scattering theory for the optical potential is examined. This series arranged according to number of target particles struck in forming potential. term which involves two summed as a three-body problem. Explicit formulas calculating fixed scatterer approximation are presented. Corrections approximation, one correction closure, another due nonlocality two-body interaction, relation between this work and other formal rearrangements presented.SCATTERING THEORY. Optical Multiple...
A nonstatic model for elastic pion-nucleon scattering is developed using knowledge of the analytic structure amplitude and partial wave $\frac{N}{D}$ dispersion techniques. In $S$, $D$, $F$ channels equivalent to a separable potential which includes coupling inelastic channels. $P$-wave nucleon pole arises from absorption emission pion included. more general incorporates both term ${P}_{11}$ channel. This capable reproducing change sign present in phase shifts. The necessary information...
A method for constructing energy-dependent separable potentials of the form $V=\ensuremath{\lambda}(E)|v><v|$ from (complex) elastic scattering phase shifts is presented. The coupling constant $\ensuremath{\lambda}(E)$ shown to satisfy a dispersion relation as consequence requirement multichannel unitarity. It this knowledge analytic properties which makes it possible solve inverse problem. further demonstrated that in some cases problem can still be solved analytically even when shift...
We suggest a form of the off-shell pion-nucleon amplitude which is motivated by simple field-theoretic considerations. This contains momentum-dependent factor $v(k)$ we determine solving an inverse scattering problem, using experimental phase shifts and inelasticities as input.
The method developed in a previous paper for the construction of separable representations $T$ matrices is extended. It shown that representation we propose valid vicinity specified off-shell points. Since points considered include those with arbitrary negative-energy parameters, presented here should be value bound-state three-body problem.
In relativistic heavy-ion collisions, the strong Lorentz-contracted electromagnetic fields are capable of producing copious numbers lepton pairs through two-photon mechanism. Monte Carlo techniques have been developed that allow exact calculation production by this mechanism when a semi-classical approximation is made to motion two ions. Here, we develop hybrid technique enables us calculate impact parameter dependence for lepton-pair production, and using result, obtain probability...
An ambiguity in the kinematic transformation of pion-nucleon scattering amplitude from pion-nucleus center-of-mass frame to is removed by (1) requirement time-reversal invariance and (2) that relative momentum be uniquely defined. The first-order optical potential obtained an approximate evaluation target ground state matrix element transformed amplitude. Our procedure results elastic differential cross sections are significantly different those using previous transformations. Terms two-body...
A separable approximation to a local square-well potential is examined. For $s$-wave scattering it shown that rank-2 can be constructed which fits the phase shifts below 300 MeV, and also reproduces off-shell $T$-matrix elements over entire region where $T$ matrix is, itself, appreciable.
The effect of the Pauli principle on low-energy pion-nucleus interaction is examined. We find that effects do not appreciably alter estimate strength $p$-wave optical potential based free-space scattering volumes.
The Watson and the Kerman-McManus-Thaler formulations of multiple scattering problems are compared transformations between one other given. Some numerical studies effects certain approximations also presented.
An atmospheric neutrino oscillation tool that uses full three-neutrino probabilities and a treatment of the Mikheyev-Smirnov-Wolfenstein effect, together with an analysis K2K, MINOS, CHOOZ data, is used to examine bounds on ${\ensuremath{\theta}}_{13}$. The recent, more finely binned, Super-K data are employed. For $L/{E}_{\ensuremath{\nu}}\ensuremath{\gtrsim}{10}^{4}\text{ }\text{ }\mathrm{km}/\mathrm{GeV}$, we previously found significant linear in ${\ensuremath{\theta}}_{13}$ terms. This...
Experimental elastic angular distributions for pions and kaons in the region of laboratory momentum from 600 to 900 MeV/c over nuclear-Coulomb interference are analyzed extract both real imaginary part forward meson-nucleus scattering amplitude. For pions, results total cross sections extracted smaller than those found transmission experiments. The amplitude is have an interesting energy dependence. significance this result behavior hadrons nuclei discussed. kaons, only qualitative were...
A simple model for total reaction cross sections based on the impulse approximation and use of an eikonal propagator is derived. Semiquantitative approximations are used to demonstrate that determined by radius at which profile function equal one mean free path incident particle. quantitative relation between density also provided. The tested against existing data proton-nucleus $^{12}\mathrm{C}$, $^{16}\mathrm{O}$, $^{40,44,48}\mathrm{Ca}$, $^{208}\mathrm{Pb}$ targets energies from 100 MeV...
The elastic scattering of pions from finite nuclei is examined theoretically within the context impulse approximation to optical potential for relativistic Schr\"odinger and Klein-Gordon equations. kinematical relationships between potentials wave functions are specified by considerations similar those discussed Cammarata Banerjee. We find: (1) At low energy (${T}_{\ensuremath{\pi}}\ensuremath{\lesssim}50$ MeV) there a large difference solutions two (2) strong sensitivity range pion-nucleon...
We investigate the total cross section and its target dependence for ${\mathit{K}}^{+}$-nucleus scattering using a relativistic momentum-space optical potential model which incorporates relativistically normalized wave functions, invariant two-body amplitudes, covariant kinematics, an exact full-Fermi averaging integral. The definition of in presence Coulomb interaction is reviewed calculated way that consistent with what extracted from experiment. In addition, sections nucleus deuteron are...
We investigate theoretical approaches to pion-nucleus elastic scattering at high energies (300\ensuremath{\le}${\mathit{T}}_{\mathrm{\ensuremath{\pi}}}$\ensuremath{\le}1 GeV). A ``model-exact'' calculation of the lowest-order microscopic optical model, carried out in momentum space and including full Fermi averaging integration, a realistic off-shell pion-nucleon amplitude fully covariant kinematics, is used calibrate much simpler theory. The theory utilizes local potential with an eikonal...
Field theoretic aspects of the pion field interacting with a nucleus are investigated. The quantum nature is shown to be most simply and fundamentally incorporated into multiple scattering theory through Klein-Gordon equation. This accomplished so that crossing symmetry amplitude manifest can maintained without recourse nonlinear equations. We give specific examples calculating first second order optical potential in static approximation. Our approach provides clean separation between energy...