Abstract
We investigate a nonrelativistic version of Georgi’s “unparticle physics.” We define the unnucleus as a field in a nonrelativistic conformal field theory. Such a field is characterized by a mass and a conformal dimension. We then consider the formal problem of scatterings to a final state consisting of a particle and an unnucleus and show that the differential cross-section, as a function of the recoil energy received by the particle, has a power-law singularity near the maximal recoil energy, where the power is determined by the conformal dimension of the unnucleus. We argue that unlike the relativistic unparticle, which remains a hypothetical object, the unnucleus is realized, to a good approximation, in nuclear reactions involving emission of a few neutrons, when the energy of the final-state neutrons in their center-of-mass frame lies in the range between about 0.1 MeV and 5 MeV. Combining this observation with the known universal properties of fermions at unitarity in a harmonic trap, we predict a power-law behavior of an inclusive cross-section in this kinematic regime. We verify our predictions with previous effective field theory and model calculations of the 6He(p,pα)2n, 3H(π−,γ)3n, and 3H(μ−,νμ)3n reactions and discuss opportunities to measure unnuclei at radioactive beam facilities.
Funder
U.S. Department of Energy
Simons Foundation
Deutsche Forschungsgemeinschaft
Bundesministerium für Bildung und Forschung
Publisher
Proceedings of the National Academy of Sciences
Cited by
15 articles.
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