The low lying axial-vector mesons as dynamically generated resonances

Abstract

We make a theoretical study of the s-wave interaction of the nonet of vector mesons with the octet of pseudoscalar mesons starting from a chiral invariant Lagrangian and implementing unitarity in coupled channels. By looking for poles in the unphysical Riemann sheets of the unitarized scattering amplitudes, we get two octets and one singlet of axial-vector dynamically generated resonances. The poles found can be associated to most of the low lying axial-vector resonances quoted in the Particle Data Book: b 1 (1235), h 1 (1170), h 1 (1380), a 1 (1260), f 1 (1285) and two poles to the K 1 (1270) resonance. We evaluate the couplings of the resonances to the V P states and the partial decay widths in order to reinforce the arguments in the discussion.

Axial resonances a 1(1260), b 1(1235) and their decays from the lattice

“…Our lattice result for g a 1 ρπ is also close to the value g phen a 1 ρπ ≈ 0.9 GeV obtained using an Unitarized Effective Field Theory approach [23] (converted to our convention).…”

“…More recently, axial mesons emerged as dynamically generated resonances in the study of scattering between pseudoscalar and vector mesons based on chiral Lagrangians [20][21][22]. Unitarized Chiral Perturbation Theory models render poles related to axial mesons dynamically although these are not present in the original Lagrangian [23]. This approach was used also to determine the dependence of their masses and widths as a function of number of colors (N c ).…”

The possible members of the $$5^1S_0$$ 5 1 S 0 meson nonet

“…The masses of the K (2153) and K (2418) are taken to be 2153 ± 20 MeV and 2418 ± 49 MeV, respectively. The K (1460) mass is taken to be 1460 MeV [55] [56][57][58], which means they might have large hadron-molecular components in their wave functions. If so, both the SHO and RQM wave functions derived from the simple qq picture, would be not appropriate and could lead to the big discrepancies between the experiments and the 3 P 0 model predictions.…”

Different nature of rho and a1

“…[4] and later in Ref. [5]. In these works a coupled-channel treatment of π-ρ and K-K * has been presented.…”

“…The a 1 meson, on the other hand, can be understood as a meson-molecule state [4,5,6,7] mainly formed by the attractive interaction between pion and ρ meson. A key issue here is that the meson-meson interactions are fixed by chiral symmetry breaking.…”