Deformed nucleon, vorticity and proton spin

Abstract

Abstract. In the framework of the proposed by the author Strongly Correlated Quark Model the valence quarks are treated as vortical solitons, and the proton spin arises from the additive sum of the valence quark vorticities. The spin "crisis" is a manifestation of the irrotational character of vortical fields quarks. JINR, Dubna, Russia E-mail: genis@jinr.ruOne the most challenging key questions in hadronic physics is understanding the spin structure of the proton. From non-relativistic quark model we know that the proton spin is composed of spins of constituent quarks additive sum of which gives one half. However, deep inelastic scattering experiments have found out that only ∼ 20% of proton spin is carried out by quark spins. It is natural to describe the proton spin according to the sum rulewhere J q and J g are total angular momenta of quarks and gluons, respectively. There are two important tasks emerging from this sum rule: to separate total angular momenta both quarks and gluons into intrinsic spins and orbital angular momenta and to define observable quantities corresponing them. So, question is: where does the proton spin come from? In this paper we describe the spin of the proton as arising from the hadronic flow circulating around valence quarks. Considerations are performed in the framework of so-called Strongly Correlated Quark Model (SCQM) [1]. The ingredients of the model are the following. Suppose a single quark of definite color embedded in vacuum. Because of its color charge the surrounding vacuum becomes polarized that in turn results in a creation of quark and gluon condensate. The quark, as a defect in vacuum, experiences a pressure from the surrounding vacuum due to the zero point radiation or quantum fluctuations. If we place the corresponding antiquark in the vicinity of the first one their color fields of opposite sign interfere destructively in the overlapped regions eliminating each other, mostly in space between them. This effect leads to decreasing of condensates density in the same regions and overbalancing of the vacuum pressure acting on quark (antiquark) from all directions. As a result the attractive force between quark and antiquark emerges and quark and antiquark start to move towards each other. The density of the remaining condensate around quark (antiquark) is identified with hadronic matter distribution. At maximum displacement in qq− system, that corresponds to small overlapping of polarization fields, hadronic matter distributions have maximum extent and values. The more close quarks come to each other, the more is the destructive interference of their fields in between them, and the less hadronic matter distributions remain around the quarks. In that way quark and antiquark start to oscillate near their center of mass. For such interacting qq− pair located on X axis at distance 2x from each other the total Hamiltonian is