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HK: Physik der Hadronen und Kerne

HK 12: Theorie

HK 12.7: Vortrag

Freitag, 4. März 2005, 18:15–18:30, TU MA041

A Nucleon in a Tiny Box — •Harald W. Grießhammer — T39, Technischen Universität München, D-85747 Garching

Chiral Perturbation Theory techniques are used to compute the nucleon mass-shift due to finite-volume and temperature effects. We interpolate between the infinite-volume limit and very small volumes (the “є-régime” 1/Λ_χ≪ L∼β≪ 1/m_π as first discussed by Gasser and Leutwyler). This first extension to nucleons can be used to extrapolate lattice results from temporal and spatial sizes smaller than the pion cloud and avoids the numerically costly simulation of Physics well under theoretical control. Based on the two leading orders, we discuss the convergence of the expansion as a function of the lattice size and quark masses. An extraction of the experimentally ill-determined low-energy coefficients c₂, c₃ of the chiral Lagrangean from lattice simulations at small volumes and a “magic” ratio β=1.22262 L is possible. Further observables are commented on.