James Charbonneau

Topological currents in neutron stars: kicks, precession, toroidal fields, and magnetic helicity

The effects of anomalies in high density QCD are striking. We consider a direct application of one of these effects, namely topological currents, on the physics of neutron stars. All the elements required for topological currents are present in neutron stars: degenerate matter, large magnetic fields, and parity violating processes. These conditions lead to the creation of vector currents capable of carrying momentum and inducing magnetic fields. We estimate the size of these currents for many representative states of dense matter in the neutron star and argue that they could be responsible for the large proper motion of neutron stars (kicks), the toroidal magnetic field and finite magnetic helicity needed for stability of the poloidal field, and the resolution of the conflict between type-II superconductivity and precession. Though these observational effects appear unrelated, they likely originate from the same physics — they are all P-odd phenomena that stem from a topological current generated by parity violation.

A Constraint-Based Approach to the Chiral Magnetic Effect

We propose a way to introduce the currents responsible for the Chiral Magnetic Effect, and similar phenomena, into the AdS/CFT description. Such currents are thought to occur in heavy ion collisions due to topologically non-trivial field configurations and in dense stars due to beta decay. They may be responsible for the P and CP odd effects seen at RHIC and the anomalously large velocities observed in some pulsars. We discuss the boundary conditions that allow the phenomenon to exist in real systems and show how one would introduce similar boundary conditions into a holographic model of QCD such that the current is reproduced.

Novel mechanism for type I superconductivity in neutron stars

We suggest a mechanism that may resolve a conflict between the precession of a neutron star and the widely accepted idea that protons in the bulk of the neutron star form a type II superconductor. We will show that if there is a persistent, nondissipating current running along the magnetic flux tubes the force between magnetic flux tubes may be attractive, resulting in a type I, rather than a type II, superconductor. If this is the case, the conflict between the observed precession and the canonical estimation of the Landau-Ginzburg parameter

Large pulsar kicks from topological currents

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The Fluid/gravity correspondence: Lectures notes from the 2008 Summer School on Particles, Fields, and Strings

(which suggests type-II behavior) will automatically be resolved. We calculate the interaction between two vortices, each carrying a current

Multimodel fine-resolution ensembles for short-range forecasts in mountainous terrain

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ComPAIR: A New Online Tool Using Adaptive Comparative Judgement to Support Learning with Peer Feedback

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The Axial Anomaly and Large Pulsar Kicks

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Assessing interdisciplinary thinking using a novel card sort activity

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A tool that changes the way students learn through peer assessment: The ComPAIR Project at UBC

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