N c -insensitivity of QCD 2 A
Year: 2024
Type: article
Abstract: The spectrum of two-dimensional adjoint QCD is surprisingly insensitive to the number of colors N c of its gauge group. It is argued that the cancellation of finite N c terms is rather natural and ultimately a consequence of the singularity structure of the theory. In short, there are no finite N c terms, hence effectively there cannot be any finite N c singular terms, since the former are necessary to guarantee well-behaved principal value integrals. We evaluate and categorize the matrix elements of the theory’s light-cone Hamiltonian to show how terms emerging from finite N c contributions to the anticommutator cancel against contributions from the purely finite N c term of the Hamiltonian. The cancellation is not complete; finite terms survive and modify the spectrum, as is known from numerical work. Additionally we show that several parton-number changing finite N c matrix elements vanish independently of finiteness requirements. In particular, there is only one trace-diagonal finite N c correction. It seems therefore that considering matrix elements rather than individual contributions can provide substantial simplifications when computing the spectrum of a theory with a large symmetry group. Published by the American Physical Society 2024
Author: Uwe Trittmann
Institution: Otterbein University
Language: English
Subfield: Nuclear and High Energy Physics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: hybrid
Funders: Simons Foundation, Ohio State University
OpenAlex ID: W4402861680