Electromagnetism with Magnetic Charge and Two Photons

The Dirac approach to include magnetic charge in Maxwell's equations places the magnetic charge at the end of a string on which the the fields of the theory develop a singularity. In this paper an alternative formulation of classical electromagnetism with magnetic and electric charge is given by introducing a second pseudo four-vector potential, C_mu, in addition to the usual four- vector potential, A_mu. This avoids the use of singular, non-local variables (i.e. Dirac strings) in electrodynamics with magnetic charge, and it makes the treatment of electric and magentic charge more symmetric, since both charges are now gauge charges.Comment: 20 page, 0 figures. Published in AJP. Proposes the possiblity of an additional U(1) magnetic, gauge boso

The Effects of Disability Insurance: Evidence from Social Security's Disabled-Widow Program

This study measures the effect of disability insurance on labor supply and health insurance coverage. The effect is identified by a policy in 1990 that increased the generosity of Social Security's disabled-widow program. Using data from the Current Population Survey, the results suggest that, in this context, disability benefits led to a one-to-one decline in labor force participation, employment, and private insurance coverage. The results imply that the demand for disability benefits may not reflect a latent demand for public health insurance

Health Information and Social Security Entitlements

This study examines whether new health information, obtained through medical screening, affects entitlements to Social Security benefits. Random assignment of information is derived from a unique feature of the Continuous National Health and Nutrition Examination Survey. To examine the effect of information on entitlements, the survey data are matched to administrative data from the Social Security Administration. The results suggest that new health information leads to delayed entitlements, particularly among workers near the early retirement age

The time-dependent non-Abelian Aharonov-Bohm effect

In this article, we study the time-dependent Aharonov-Bohm effect for non-Abelian gauge fields. We use two well known time-dependent solutions to the Yang-Mills field equations to investigate the Aharonov-Bohm phase shift. For both of the solutions, we find a cancellation between the phase shift coming from the non-Abelian "magnetic" field and the phase shift coming from the non-Abelian "electric" field, which inevitably arises in time-dependent cases. We compare and contrast this cancellation for the time-dependent non-Abelian case to a similar cancellation which occurs in the time-dependent Abelian case. We postulate that this cancellation occurs generally in time-dependent situations for both Abelian and non-Abelian fields.Comment: 17 pages revtex, 3 figures published versio