UHM High Energy Physics Seminar - Previous Years

Neutron Limit on the Strongly-Coupled Chameleon Field

by Prof. Dmitry Pushin (NIST)

112 (WAT)



One of the major open questions of cosmology is the physical origin of the dark energy. There are a few sets of theories which might explain this origin that could be tested experimentally. The chameleon dark energy theory postulates self-interacting scalar field that couples to matter. This coupling induces a screening mechanism chosen so that the field amplitude is nonzero in empty space but is greatly suppressed in regions of terrestrial matter density. On behalf of the INDEX collaboration, I will report the most stringent upper bound on the free neutron-chameleon coupling in the strongly-coupled limit of the chameleon theory using neutron interferometric techniques. In our experiment we measure neutron phase induced by chameleon field. We report a 95% confidence level upper bound on the neutron-chameleon coupling ranging from β < 4.7 × 106 for a Ratra- Peebles index of n = 1 in the nonlinear scalar field potential to β < 2.4×107 for n = 6, one order of magnitude more sensitive than the most recent free neutron limit for intermediate n.
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