A solution to the rho-. pi. puzzle: Spontaneously broken symmetries of the quark model

Journal Article · Sun Aug 01 00:00:00 EDT 1976 · Phys. Rev., D; (United States)

DOI:https://doi.org/10.1103/PhysRevD.14.809· OSTI ID:7266774

Caldi, D G; Pagels, H

This article proposes a solution to the long-standing rho-..pi.. puzzle: How can the rho and ..pi.. be members of a quark model U(6) 36 and the ..pi.. be a Nambu-Goldstone boson satisfying partial conservation of the axial-vector current (PCAC) Our solution to the puzzle requires a revision of conventional concepts regarding the vector mesons rho, ..omega.., K*, and phi. Just as the ..pi.. is a Goldstone state, a collective excitation of the Nambu--Jona-Lasinio type, transforming as a member of the (3, 3) + (3, 3) representation of the chiral SU(3) x SU(3) group, so also the rho transforms like (3, 3) + (3, 3) and is also a collective state, a ''dormant'' Goldstone boson that is a true Goldstone boson in the static chiral U(6) x U(6) limit. The static chiral U(6) x U(6) is to be spontaneously broken to static U(6) in the vacuum. Relativisitc effects provide for U(6) breaking and a massive rho. This viewpoint has many consequences. Vector-meson dominance is a consequence of spontaneously broken chiral symmetry: the mechanism that couples the axial-vector current to the ..pi.. couples the vector current to the rho. The transition rate is calculated as ..gamma../sub rho/ /sup -1/ = f/sub pi//m/sub rho/ in rough agreement with experiment. This picture requires soft rho's to decouple. The chiral partner of the rho is not the A/sub 1/ but the B (1235). The experimental absence of the A/sub 1/ is no longer a theoretical embarrassment in this scheme. As the analog of PCAC for the pion we establish a tensor-field identity for the rho meson in which the rho is interpreted as a dormant Goldstone state. The decays delta ..-->.. eta + ..pi.., B ..-->.. ..omega.. + ..pi.., epsilon ..-->.. 2..pi.. are estimated and are found to be in agreement with the observed rates. A static U(6) x U(6) generalization of the ..sigma.. model is presented with the ..pi.., rho, sigma, B in the (6, 6) + (6, 6) representation. The rho emerges as a dormant Goldstone boson in this model. (AIP)

• Research Organization: The Rockefeller University, New York, New York 10021
• OSTI ID: 7266774
• Journal Information: Phys. Rev., D; (United States), Vol. 14:3
• Country of Publication: United States
• Language: English

Related Subjects

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
PIONS
QUARK MODEL
SYMMETRY BREAKING
RHO-765 RESONANCES
PARTICLE PROPERTIES
SYMMETRY GROUPS
CHIRAL SYMMETRY
GOLDSTONE BOSONS
MELOSH TRANSFORMATION
PCAC THEORY
SU-3 GROUPS
U-6 GROUPS
BOSONS
COMPOSITE MODELS
ELEMENTARY PARTICLES
HADRONS
LIE GROUPS
MATHEMATICAL MODELS
MESON RESONANCES
MESONS
PARTICLE MODELS
POSTULATED PARTICLES
PSEUDOSCALAR MESONS
RESONANCE PARTICLES
SU GROUPS
SYMMETRY
U GROUPS
VECTOR MESONS
645303* - High Energy Physics- Particle Invariance Principles & Symmetries- Applications to Strong Interactions- (-1987)