Guest-Editor Matti Pitkänen's Statement on Steven K. Kauffmann’s Work

Abstract

For 26 years superstrings have been seen as the only game in the town. Besides the well-known problems of M-theory there are also some other clouds in the horizon. For instance, the recently discovered Lamb shift anomaly of muonic hydrogen can be seen as a challenge of either QED or QCD and even of the entire QFT approach underlying M-theory. With inspiration coming from these anomalies Steven Kauffmann discusses in this issue his own proposal about what the return to the roots could mean. Steven Kauffmann’s proposal is to give up Dirac and d’Alembert type equations altogether and return to single particle level. This means that one identifies single particle Hamiltonian as a generalization of the relativistic formula for the energy of charged particle and allows only positive energies so that only the positive square root is allowed. In this approach CP and CPT are not automatic symmetries: C or CP, together with "crossing" of "charge equivalence" symmetry, must be explicitly imposed– the resulting field theory is explicitly non-local in its configuration regime due to the influence of the square root even at the second-quantized level. This could make it easier to understand CP and CPT breaking. The approach has to meet burdensome technical challenges due to the appearance of the square root, and the usual puzzles of massless gauge theories, which are only partially dynamical and quantizable, remain to be fully assimilated into its particular context. Also the construction of counterparts of Feynman diagrams in this framework is a considerable challenge. These problems are discussed in the articles of this issue. I hope that the work of Steven Kauffmann can serve as inspiration for other thinkers.