1993/11/23 by S. Balk, Balk, S., Amon Ilakovac +5
Engineering · Physics and Astronomy · #FOS: Physical sciences #High Energy Physics - Phenomenology (hep-ph) #Particle physics theoretical and experimental studies #Quantum Chromodynamics and Particle Interactions #Superconducting Materials and Applications
paper · pdf · doi:10.48550/arxiv.hep-ph/9311348
openalex publication_date 1993/11/23 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
We point out that there exist two different formulations of the Heavy Quark Effective Theory (HQET). One formulation of HQET was mostly developed at Harvard and involves the use of the equation of motion to eliminate the small components of the heavy quark field. The second formulation, developed in Mainz, involves a series of Foldy-Wouthuysen-type field transformations which diagonalizes the heavy quark Lagrangian. Starting at O(1/mQ2) the two formulations are different in that their effective Lagrangians, their effective currents, and their fields differ. However, when these three differences are properly taken into account, the two alternative formulations lead to identical S-matrix elements. This is demonstrated in an explicit example at O(1/mQ2). We point to an essential difficulty of the Harvard HQET in that the Harvard effective fields are not properly normalized starting at order O(1/mQ2).