Nuclear Physics Seminar

An effective theory for light lattice nuclei

Johannes Kirscher (The Hebrew University, Jerusalem, Israel)

Time: Thursday, May 28th, 2015, 10:00 am

How sensitive are key features of light nuclear systems to a variation in the pion mass? As the lightest meson, the impact of the interaction between a pion and a nucleon is significantly larger relative to other meson or baryon couplings. It guides the systematic derivation of nuclear properties from the fundamental theory of quantum chromodynamics (QCD) via, e.g., chiral perturbation theory. Recently, lattice techniques were developed to obtain few-nucleon amplitudes directly from QCD. Even with the unnaturally large quark, and thus pion masses used to extract these results, the approach promises to be the long-sought bridge between nuclear and particle physics. I will present an analysis of lattice QCD data in an effective-field-theory framework. In particular, the analog of the effective field theory without pions, which is established for the description of two and three-nucleon systems and is a promising candidate for an interaction theory for multi-nucleon systems at physical pion masses consistent with QCD, is employed. At leading order in this EFT, the three and four-nucleon system is investigated. The Phillips and Tjon line constitute peculiar features tied to the fine-tuned nature of nuclear physics. Whether those peculiarities result from the physically observed or emerge likewise at larger values of the pion mass will be the main result of the presented work. To exemplify the sensitivity of a few-body observable to the structure of the interaction at short distances, a discrepancy between two incarnations of a next-to-leading-order calculation in the charged 3-helium is presented at the physical pion mass.

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