Light scalar mesons as manifestation of spontaneously broken chiral symmetry

Abstract

It is shown that all predictions for the light scalars, based on their four-quark nature, are supported by experiment. The future research program is outlined also. PACS numbers: PACS numbers: 12.39.-x, 13.40.-f, 13.60. Le, 13.75. Lb 1 Introduction OVERTURE Peter Higgs, C. R. Physique 8 (2007) 970-972:" Another example, which comes closer to the kind of symmetry breaking which is of interest in particle physics, is superfluidity. In 1947 Bogoliubov studied Bose condensation of an infinite system of neutral spinless bosons with short-range repulsive two-body interactions. Such a condensate is characterised by a 'macroscopic wave function' (the order parameter) which is complex; its modulus squared is a measure of the observable condensate density, but its argument (which is unobservable) is arbitrary, thus breaking the symmetry of the dynamics under rotations of the boson wave functions in the Argand diagram. The short-range interactions are represented in the second-quantised Hamiltonian by a term proportional to the square of the particle density, that is, to a quartic in the components of the scalar quantum field." See also, N.N. OutlineThe a 0 (980) and f 0 (980) mesons are well-established parts of the proposed light scalar meson nonet [1]. From the beginning, the a 0 (980) and f 0 (980) mesons became one of the central problems of nonperturbative QCD, as they are important for understanding the way chiral symmetry is realized in the low-energy region and, consequently, for understanding confinement. Many experimental and theoretical papers have been devoted to this subject. There is much evidence that supports the four-quark model of light scalar mesons [2,3].