A method to measure vacuum birefringence at FCC-ee
It is well-known that the Heisenberg-Euler-Schwinger effective Lagrangian predicts that a vacuum with a strong static electromagnetic field turns birefringent. We propose a scheme that can be implemented at the planned FCC-ee, to measure the nonlinear effect of vacuum birefringence in electrodynamic...
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Main Authors | , |
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Format | Journal Article |
Language | English |
Published |
10.05.2016
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Subjects | |
Online Access | Get full text |
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Summary: | It is well-known that the Heisenberg-Euler-Schwinger effective Lagrangian
predicts that a vacuum with a strong static electromagnetic field turns
birefringent. We propose a scheme that can be implemented at the planned
FCC-ee, to measure the nonlinear effect of vacuum birefringence in
electrodynamics arising from QED corrections. Our scheme employs a pulsed laser
to create Compton backscattered photons off a high energy electron beam, with
the FCC-ee as a particularly interesting example. These photons will pass
through a strong static magnetic field, which changes the state of polarization
of the radiation - an effect proportional to the photon energy. This change
will be measured by the use of an aligned single-crystal, where a large
difference in the pair production cross-sections can be achieved. In the
proposed experimental setup the birefringence effect gives rise to a difference
in the number of pairs created in the analyzing crystal, stemming from the fact
that the initial laser light has a varying state of polarization, achieved with
a rotating quarter wave plate. Evidence for the vacuum birefringent effect will
be seen as a distinct peak in the Fourier transform spectrum of the
pair-production rate signal. This tell-tale signal can be significantly above
background with only few hours of measurement, in particular at high energies. |
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DOI: | 10.48550/arxiv.1605.02861 |