1,748 research outputs found
Quantized Casimir Force
We investigate the Casimir effect between two-dimensional electron systems
driven to the quantum Hall regime by a strong perpendicular magnetic field. In
the large separation (d) limit where retardation effects are essential we find
i) that the Casimir force is quantized in units of 3\hbar c \alpha^2/(8\pi^2
d^4), and ii) that the force is repulsive for mirrors with same type of
carrier, and attractive for mirrors with opposite types of carrier. The sign of
the Casimir force is therefore electrically tunable in ambipolar materials like
graphene. The Casimir force is suppressed when one mirror is a charge-neutral
graphene system in a filling factor \nu=0 quantum Hall state.Comment: 4.2 page
Constraints on Light Pseudoscalars Implied by Tests of the Gravitational Inverse-Square Law
The exchange of light pseudoscalars between fermions leads to a
spin-independent potential in order g^4, where g is the Yukawa
pseudoscalar-fermion coupling constant. This potential gives rise to detectable
violations of both the weak equivalence principle (WEP) and the gravitational
inverse-square law (ISL), even if g is quite small. We show that when
previously derived WEP constraints are combined with those arisingfrom ISL
tests, a direct experimental limit on the Yukawa coupling of light
pseudoscalars to neutrons can be inferred for the first time (g_n^2/4pi < 1.6
\times 10^-7), along with a new (and significantly improved) limit on the
coupling of light pseudoscalars to protons.Comment: 12 pages, Revtex, with 1 Postscript figure (submitted to Physical
Review Letters
Evidence for Solar Influences on Nuclear Decay Rates
Recent reports of periodic fluctuations in nuclear decay data of certain
isotopes have led to the suggestion that nuclear decay rates are being
influenced by the Sun, perhaps via neutrinos. Here we present evidence for the
existence of an additional periodicity that appears to be related to the Rieger
periodicity well known in solar physics.Comment: Presented at the Fifth Meeting on CPT and Lorentz Symmetry,
Bloomington, Indiana, June 28-July 2, 201
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