Physics

Probing Non-Standard Charges

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Science  18 Apr 2008:
Vol. 320, Issue 5874, pp. 290
DOI: 10.1126/science.320.5874.290b

The Standard Model of particle physics describes three of the four fundamental forces, detailing the strengths of interactions among the protons, electrons, and neutrons that make up atoms, as well as the family of quarks that in turn make up these particles. The framework gives rise to charge quantization, as measured in discrete units of electron charge e, and also the charge neutrality of atoms. However, the violation of certain symmetries that describe the underlying physics of all these forces—as is evident from the dominance of matter over antimatter in the universe—indicates that there is something happening beyond the Standard Model. Much theoretical and experimental effort is directed toward exploring this regime, with some work suggesting that the notion of charge quantization and charge neutrality should be abandoned. In efforts to detect the miniscule charges that could explain the broken symmetries, Arvanitaki et al. describe a sensitive method for detecting charge on an atom based on the interference of atom waves. They argue that during splitting and recombination of a condensed cloud of rubidium atoms, a departure from charge neutrality of as little as 10−28 e should be detectable as a phase shift in the interfering atom waves. This cold atom approach may provide an alternate route to looking beyond the Standard Model. — ISO

Phys. Rev. Lett. 100, 120407 (2008).

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