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Selected Works

High energy physics phenomenology

John Swain

Articles 1 - 7 of 7

Full-Text Articles in Physics

Electric Dipole Moments And Polarizability In The Quark-Diquark Model Of The Neutron, Y. N. Srivastava, A. Widom, J. Swain, O. Panella Feb 2011

Electric Dipole Moments And Polarizability In The Quark-Diquark Model Of The Neutron, Y. N. Srivastava, A. Widom, J. Swain, O. Panella

John Swain

For a bound state internal wave function respecting parity symmetry, it can be rigorously argued that the mean electric dipole moment must be strictly zero. Thus, both the neutron, viewed as a bound state of three quarks, and the water molecule, viewed as a bound state of ten electrons two protons and an oxygen nucleus, both have zero mean electric dipole moments. Yet, the water molecule is said to have a nonzero dipole moment strength $d=e\Lambda $ with $\Lambda_{H_2O} \approx 0.385\ \dot{A}$. The neutron may also be said to have an electric dipole moment strength with ...


Effects Of Anomalous Charged Current Dipole Moments Of The Tau On The Decay $\Tau^-\To\Nu_\Tau\Pi^-\Pi^0$, Maria-Teresa Dova, Pablo Lacentre, John Swain, Lucas Taylor Feb 2011

Effects Of Anomalous Charged Current Dipole Moments Of The Tau On The Decay $\Tau^-\To\Nu_\Tau\Pi^-\Pi^0$, Maria-Teresa Dova, Pablo Lacentre, John Swain, Lucas Taylor

John Swain

We analyse the process $\tau^-\to\nu_\tau\pi^-\pi^0$ allowing for anomalous weak charged current magnetic and electric dipole moment interactions and determine the effects on the differential and total decay rates. Using recent experimental data we determine the following values for the anomalous magnetic and electric dipole moment parameters, respectively: $\kappa = 0.16 \pm 0.08; and |\tilde\kappa| = 0.88^{+0.25}_{-0.35}.$


Echoes Of The Fifth Dimension?, Luis A. Anchordoqui, Thomas P. Mccauley, Stephen Reucroft, John Swain Feb 2011

Echoes Of The Fifth Dimension?, Luis A. Anchordoqui, Thomas P. Mccauley, Stephen Reucroft, John Swain

John Swain

In this article we examine the question of whether the highest energy cosmic ray primaries could be ultra relativistic magnetic monopoles. The analysis is performed within the framework of large compact dimensions and TeV scale quantum gravity. Our study indicates that while this hypothesis must be regarded as highly speculative it cannot be ruled out with present data.


Effect Of The 3k Background Radiation On Ultrahigh Energy Cosmic Rays, L. A. Anchordoqui, M. T. Dova, L. N. Epele, J. D. Swain Feb 2011

Effect Of The 3k Background Radiation On Ultrahigh Energy Cosmic Rays, L. A. Anchordoqui, M. T. Dova, L. N. Epele, J. D. Swain

John Swain

In this work we re-examine the opacity of the cosmic background radiation to the propagation of extremely high energy cosmic rays. We use the continuous energy loss approximation to provide spectral modification factors for several hypothesized cosmic ray sources. Earlier problems with this approximation are resolved including the effects of resonances other than the $\Delta$.


Constraints On The Tau Neutrino Mass And Mixing From Precise Measurements Of Tau Decay Rates, J. Swain, L. Taylor Jan 2011

Constraints On The Tau Neutrino Mass And Mixing From Precise Measurements Of Tau Decay Rates, J. Swain, L. Taylor

John Swain

We have derived constraints on the tau neutrino mass and fourth generation mixing from an analysis of the partial widths of tau lepton decays, in particular: τ¯→e¯ν⁻eντ, τ¯→μ¯ν⁻μντ, τ →π¯ντ, and τ →K¯ντ. We present predictions for the tau decay widths, allowing for a non-zero tau neutrino mass, mντ, and for mixing with a neutrino of mass mνL > MZ/2, which is parametrised using a Cabibbo-like mixing angle, θL. By comparison of these theoretical predictions with the experimental measurements, we obtain the following bounds at the 90% confidence level: mντ < 42 MeV ...


Anomalous Charged Current Couplings Of The Tau And Implications For Tau Compositeness And Two-Higgs Doublet Models, Maria-Teresa Dova, John Swain, Lucas Taylor Jan 2011

Anomalous Charged Current Couplings Of The Tau And Implications For Tau Compositeness And Two-Higgs Doublet Models, Maria-Teresa Dova, John Swain, Lucas Taylor

John Swain

The leptonic branching fractions of the tau lepton are sensitive to anomalous charged current interactions. We use recent experimental measurements to determine the weak charged current magnetic and electric dipole moments and the Michel parameter with unprecedented precision. These results are then used to constrain the tau compositeness scale and the allowed parameter space for Higgs doublet models.


Constraints On Anomalous Charged Current Couplings, Tau Neutrino Mass And Fourth Generation Mixing From Tau Leptonic Branching Fractions, Maria Teresa Dova, John Swain, Lucas Taylor Jan 2011

Constraints On Anomalous Charged Current Couplings, Tau Neutrino Mass And Fourth Generation Mixing From Tau Leptonic Branching Fractions, Maria Teresa Dova, John Swain, Lucas Taylor

John Swain

We use recent experimental measurements of tau branching fractions to determine the weak charged current magnetic and electric dipole moments of the tau and the Michel parameter η with unprecedented precision. These results are then used to constrain the tau compositeness scale and the allowed parameter space for Higgs doublet models. We also present new constraints on the mass of the tau neutrino and its mixing with a fourth generation neutrino.