Particle Physics Seminar: Effective field theory for pions and a dilatonic meson

Abstract:

Numerical simulations of QCD-like theories which are chirally broken but exhibit a very small beta function reveal a flavor-singlet scalar, or "dilatonic meson," which is much lighter than any other states except pions. We develop a systematic low-energy expansion for the pions and the dilatonic meson, in which the presence of the latter is attributed to an approximate scale symmetry. In order to justify the power counting we invoke the Veneziano limit, in which the number of flavors Nf in the fundamental representation grows in proportion with the number of colors Nc, while the ratio Nf/Nc is kept close to, but below, the critical value where the conformal window is entered.

Seminar Organizer: Prof. Nissan Itzhaki