From well-known tensor mesons to yet unknown axial-tensor mesons

Abstract

While the ground-state tensor (J P C = 2 ++ ) mesons a 2 (1320), K * 2 (1430), f 2 (1270), and f ′ 2 (1525) are well known experimentally and form an almost ideal nonet of quark-antiquark states, their chiral partners, the ground-states axial-tensor (J P C = 2 −− ) mesons are poorly settled: only the kaonic member K 2 (1820) of the nonet has been experimentally found, whereas the isovector state ρ 2 and two isoscalar states ω 2 and φ 2 are still missing. Here, we study masses, strong, and radiative decays of tensor and axial-tensor mesons within a chiral model that links them: the established tensor mesons are used to test the model and to determine its parameters, and subsequently various predictions for their chiral partners, the axial-tensor mesons, are obtained. The results are compared to current lattice QCD outcomes as well as to other theoretical approaches and show that the ground-state axial-tensor mesons are expected to be quite broad, the vector-pseudoscalar mode being the most prominent decay mode followed by the tensor-pseudoscalar one. Nonetheless, their experimental finding seems to be possible in ongoing and/or future experiments.