Gary Tupper - Academia.edu (original) (raw)

Papers by Gary Tupper

Physical review, 1991

Abstract We consider the decay of a heavy top quark into a W boson and a hard photon (gluon). Our... more Abstract We consider the decay of a heavy top quark into a W boson and a hard photon (gluon). Our results for the differential decay rate for these two processes are remarkably simple and have been independently checked. We obtain a branching ratio of 0.33% for ...

Physics Letters B, Apr 1, 2005

Extending previous work in Randall-Sundrum type models, we construct low-energy effective actions... more Extending previous work in Randall-Sundrum type models, we construct low-energy effective actions for braneworlds with a bulk scalar field, with special attention to the case of BPS branes. Holding the branes at fixed coordinate position with a general ansatz for the bulk metric, and imposing the Einstein frame as a gauge condition, we obtain a scalar-tensor theory with only one scalar degree of freedom related to the proper brane separation. The formalism is applicable even when there is direct coupling of the bulk scalar and brane matter, as in the Horava-Witten model. We further show that the usual moduli space approximation actually describes a non-BPS three-brane system.

Zeitschrift Für Physik C Particles And Fields, Sep 1, 1985

We have calculated the differential crosssection for the process dO-* W-?g (Jet). It is found tha... more We have calculated the differential crosssection for the process dO-* W-?g (Jet). It is found that, although the radiation amplitude zero, which occurs for the lowest-order process dfi~ W-7, is spoiled, there remains a very large dip. Hence, both processes can be used to measure the magnetic moment of the W boson and the value of the quark charges. The presence of a dip is a test of the gauge theoretical value for the magnetic moment of the W boson g = x + 1 = 2, and the angle at which the dip occurs is a measure of the quark charges.

arXiv (Cornell University), Jul 29, 2018

A renormalizable non-abelian vector meson dominance model coupled to pions is constructed which e... more A renormalizable non-abelian vector meson dominance model coupled to pions is constructed which exhibits a SO (4, 3) vacuum symmetry. Tree-level predictions for p-p scattering lengths and slopes at leading order are in reasonable agreement with experiment.

arXiv (Cornell University), Mar 19, 2005

We extend the Chaplygin gas model for dark matter and dark energy unification by promoting the Ch... more We extend the Chaplygin gas model for dark matter and dark energy unification by promoting the Chaplygin gas parameter A to the potential for an extra scalar with canonical kinetic energy. The hybrid model allows for accelerated Hubble expansion to be a transient effect around redshift zero.

arXiv (Cornell University), Jul 10, 2003

The hypothesis that dark matter and dark energy are unified through the Chaplygin gas is reexamin... more The hypothesis that dark matter and dark energy are unified through the Chaplygin gas is reexamined. Using a generalization of the spherical model which incorporates effects of the acoustic horizon we show that an initially perturbative Chaplygin gas evolves into a mixed system containing cold dark matter like gravitational condensate. Further, by including both condensate and residual gas, we demonstrate that the observed CMB angular and baryonic power spectra are reproduced.

arXiv (Cornell University), Nov 20, 2017

A renormalizable non-Abelian theory of strong interactions of pions, mediated by rho-mesons, is f... more A renormalizable non-Abelian theory of strong interactions of pions, mediated by rho-mesons, is formulated at tree-and at one-loop level in perturbation theory. Hadron masses are generated through spontaneous symmetry breaking using the Higgs mechanism. Quantization and gauge fixing is achieved using the generalized class of R ξ gauges. As an application of this theory, pion-pion scattering lengths are obtained at tree-level in good agreement with data.

Physical review, Mar 1, 1987

The two-photon-exchange contribution to ..pi../sup 0/..-->..e/sup +/e/sup -/..gamma.. is reeva... more The two-photon-exchange contribution to ..pi../sup 0/..-->..e/sup +/e/sup -/..gamma.. is reevaluated in the massless-electron--pointlike-pion approximation. As in the earlier work of Tupper, Grose, and Samuel, a term of order k/sup 0/ is found in the amplitude, although the coefficient of this piece was previously computed incorrectly. It is then pointed out that this term is not forbidden by Low's theorem due to the noninterchangeability of the k..-->..0 and m/sub e/..-->..0 limits. A small correction to the e/sup +/e/sup -/ invariant-mass spectrum is found.

Minerals Engineering, 2017

Positron Emission Particle Tracking observations of charge and slurry flow have shown that the pr... more Positron Emission Particle Tracking observations of charge and slurry flow have shown that the pressure drop is effectively described by an Euler equation modified by a Darcy-like term. Here we consider the inverse problem: constructing and testing approximate solutions to the new Dynamic Ergun Equation. These solutions allow the prediction of transport in tumbling mills and other systems given information on the pressure drop and charge motion.

We consider a model of dark energy/matter unification based on a k-essence type of theory similar... more We consider a model of dark energy/matter unification based on a k-essence type of theory similar to tachyon condensate models. Using an extension of the general relativistic spherical model which incorporates the effects of both pressure and the acoustic horizon we show that an initially perturbative k-essence fluid evolves into a mixed system containing cold dark matter like gravitational condensate in significant quantities.

We study a 3-brane moving in the five-dimensional bulk of the Randall-Sundrum II model. By includ... more We study a 3-brane moving in the five-dimensional bulk of the Randall-Sundrum II model. By including back-reaction of the brane on the bulk geometry we obtain a tachyon model with a linear barotropic equation of state.

Applying the Thomas-Fermi approximation to renormalizable field theories, we construct ghost cond... more Applying the Thomas-Fermi approximation to renormalizable field theories, we construct ghost condensation models that are free of the instabilities associated with violations of the null-energy condition.

Physical Review B

The occurrence of Cerenkov-like acoustic radiation when the neutron velocity exceeds the speed of... more The occurrence of Cerenkov-like acoustic radiation when the neutron velocity exceeds the speed of sound in a solid is investigated. Although the effect is found to exist theoretically, the energy loss per unit path length is so small as to preclude its observation.

Physics Letters B, 1990

We present a study of the decay of a charged Higgs into two squarks and a photon in the minimal s... more We present a study of the decay of a charged Higgs into two squarks and a photon in the minimal supersymmetric (SUSY) standard model. The process has a radiation amplitude zero whose position is determined by the electric charges of the squarks. For a certain ...

Progress of Theoretical Physics, 1985

We consider here the radiative decays of the W boson W-tobar{u}dgamma and W-to ebar{nu}egamma. As... more We consider here the radiative decays of the W boson W-tobar{u}dgamma and W-to ebar{nu}egamma. As was shown by Grose and Mikaelian, these processes have a radiation amplitude zero which occurs along a line in the Dalitz plot u, v where u=1-(2Ebar{q}/Mw) and v=1-(2Eq/Mw). Here we adopt the more convenient variables x=(2E&amp;amp;gamma/Mw) and y=(Eq-Ebar{q})/Er. The zero condition now takes the simple

Physics Letters B, 2002

We extend the world model of Kamenshchik et al. to large perturbations by formulating a Zeldovich... more We extend the world model of Kamenshchik et al. to large perturbations by formulating a Zeldovich-like approximation. We sketch how this model unifies dark matter with dark energy in a geometric setting reminiscent of M-theory. After nearly two decades of reign [1], the Einstein-de Sitter dust model has been swept aside by observations of high redshift supernovae [2] which suggest that the Hubble expansion is accelerating. When combined with the Boomerang/Maxima data [3] showing that the location of the first acoustic peak in the power spectrum of the microwave background is consistent with the inflationary prediction Ω = 1, the evidence for a net equation of state of the cosmic fluid lying in the range −1 ≤ w = P/ρ < −1/3 is compelling. Parametrically, w = P DE /(ρ DE + ρ DM) = −Ω Λ gives a ratio of unclustered dark energy to clustered dark matter of order 7:3, thereby also resolving the longstanding Ω DM < 1 puzzle [1, 4] implied by peculiar velocity fields. The theoretical implications of these dicoveries are profound.