Cusps in K --> 3 pi decays

The pion mass difference generates a pronounced cusp in K --> 3 pi decays. As has recently been pointed out by Cabibbo and Isidori, an accurate measurement of the cusp may allow one to pin down the S-wave pi pi scattering lengths to high precision. Here, we present and illustrate an effective field theory framework that allows one to determine the structure of this cusp in a straightforward manner. The strictures imposed by analyticity and unitarity are respected automatically.Comment: 14 pages, 3 figures, uses Elsevier styl

The Pion Cloud of the Nucleon: Facts and popular Fantasies

I discuss the concept of the pion cloud surrounding the nucleon and other hadrons - and its limitations.Comment: 9 pp, 3 figs, invited talk, to appear in the proceedings of the workshop ``Shape of Hadrons'' (Athens, Greece, 2006

Some recent developments in chiral perturbation theory

In this talk, I address some recent developments in chiral perturbation theory at unphysical and physical quark masses.Comment: Plenary talk delivered at the 5th International Workshop on Chiral Dynamics, Theory and Experiment (CD 2006), September 18 - 22, 2006, Durham/Chapel Hill, NC, US

Nuclear lattice simulations: Status and perspectives

I review the present status of nuclear lattice simulations. This talk is dedicated to the memory of Gerald E. Brown.Comment: Plenary talk sponsored by The European Physical Journal A -- Hadrons and Nuclei, INPC 2013, Florence, Italy, 8 pages, 3 figures, uses webofc.cl

Quark mass dependence of baryon properties

I discuss the quark mass dependence of various baryon properties derived from chiral perturbation theory. Such representations can eventually be used as chiral extrapolation functions when lattice data at sufficiently small quark masses become available. The quark mass dependence is encoded in loop and contact term contributions, the latter given in terms of low-energy constants. I stress the importance of utilizing phenomenological input to constrain a certain class of low-energy constants and discuss the ensuing theoretical uncertainty for various baryon observables, like the nucleon and the baryon octet masses, the nucleon isovector anomalous magnetic moment and the axial-vector coupling of the nucleon. I stress the role of resonance decoupling and present first results for the delta mass based on an effective field theory in which the nucleon-delta mass splitting is counted as a small parameter. I also discuss briefly the pion mass dependence of the nuclear force as derived from chiral nuclear effective field theory.Comment: 21 pp, PoS style, plenary talk at Lattice 2005, Trinity College, Dublin, Irland, 25th-30th July 200