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Colloquia
Colloquium
Friday, November 30, 2018
3:30 PM
Physics Building, Room 204

Valery Nesvizhevsky
[Host: Stefan Baessler]
Institut Laue Langevin, France
"A new approach to search for neutronantineutron oscillations, and a couple of other phenomena based on neutron reflection from surface: gravitational and whisperinggallery quantum states of neutrons"

ABSTRACT:
“An observation of neutronantineutron oscillations (nn ̅), which violate both B and B — L conservation, would constitute a scientific discovery of fundamental importance to physics and cosmology. A stringent upper bound on its transition rate would make an important contribution to our understanding of the baryon asymmetry of the universe by eliminating the postsphaleron baryogenesis scenario in the light quark sector. We show that one can design an experiment using slow neutrons that in principle can reach the required sensitivity of 10^{10 }s in the oscillation time, an improvement of 10^{4} in the oscillation probability relative to the existing limit for free neutrons. This can be achieved by allowing both the neutron and antineutron components of the developing superposition state to coherently reflect from mirrors. We present a quantitative analysis of this scenario and show that, for sufficiently small transverse momenta of n/n ̅ and for certain choices of nuclei for the n/n ̅ guide material, the relative phase shift of the n and n ̅ components upon reflection and the n ̅ annihilation rate can be small. While the reflection of n ̅ from surface looks exotic and counterintuitive and seems to contradict to the common sense, in fact it is fully analogous to the reflection of n from surface. The later phenomenon is well known and used in neutron research from its first years. We illustrate it with two selected example of gravitational and whisperinggallery quantum states of neutrons.”
[V.V. Nesvizhevsky, A.Yu. Voronin, Surprising Quantum Bounces, Imperial College Press, London, 2015]




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