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Negative superhumps are believed to arise in cataclysmic variable systemswhen the accretion disk is tilted with respect to the orbital plane. Slowretrograde precession of the line-of-nodes results in a signal---the negativesuperhump---with a period slightly less than the orbital period. Previousstudies have shown that tilted disks exhibit negative superhumps, but aconsensus on how a disk initially tilts has not been reached. Analytical workby Lai suggests that a magnetic field on the primary can lead to a tiltinstability in a disk when the dipole moment is offset in angle from the spinaxis of the primary and when the primary's spin axis is, itself, not alignedwith the angular momentum axis of the binary orbit. However, Lai did not applyhis work to the formation of negative superhumps. In this paper, we add Lai'smodel to an existing smoothed particle hydrodynamics code. Using this code, wedemonstrate the emergence of negative superhumps in the "light curve" for arange of magnetic dipole moments. We show that the period deficits calculatedfrom these negative superhumps match those in simulations using manually tilteddisks. When positive superhumps appear ($q \lesssim 0.33$), we show that theperiod excesses calculated from these signals are also consistent with previousresults. Using examples, we show that the disks are tilted, though the tiltvaries periodically, and that they precess in the retrograde direction. Themagnetic fields found to lead to the emergence of negative superhumps lie inthe kilogauss regime.

The Emergence of Negative Superhumps in Cataclysmic Variables: Smoothed Particle Hydrodynamics Simulations