14,346 research outputs found
A First Experimental Limit on In-matter Torsion from Neutron Spin Rotation in Liquid He-4
We report the first experimental upper bound to our knowledge on possible
in-matter torsion interactions of the neutron from a recent search for parity
violation in neutron spin rotation in liquid He-4. Our experiment constrains a
coefficient consisting of a linear combination of parameters involving
the time components of the torsion fields and from the nucleons
and electrons in helium which violates parity. We report an upper bound of
GeV at 68% confidence level and indicate other physical
processes that could be analyzed to constrain in-matter torsion.Comment: 12 pages, typo correcte
Asteroseismic Signatures of Stellar Magnetic Activity Cycles
Observations of stellar activity cycles provide an opportunity to study
magnetic dynamos under many different physical conditions. Space-based
asteroseismology missions will soon yield useful constraints on the interior
conditions that nurture such magnetic cycles, and will be sensitive enough to
detect shifts in the oscillation frequencies due to the magnetic variations. We
derive a method for predicting these shifts from changes in the Mg II activity
index by scaling from solar data. We demonstrate this technique on the
solar-type subgiant beta Hyi, using archival International Ultraviolet Explorer
spectra and two epochs of ground-based asteroseismic observations. We find
qualitative evidence of the expected frequency shifts and predict the optimal
timing for future asteroseismic observations of this star.Comment: 5 pages including 3 figures and 1 table, MNRAS Letters accepte
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