The nucleon form factors of the energy-momentum tensor are studied in the large-N c limit in the framework of the chiral quark-soliton model.

We compute the quark and antiquark transversity distributions in the nucleon at a low normalization point (µ ≈ 600 MeV) in the large-N c limit, where the nucleon can be described as a soliton of an effective chiral theory (chiral quark-soliton model). The flavor-nonsinglet distributions, δu(x)−δd(x) and δū(x)−δd(x), appear in leading order of the 1/N c -expansion, while the flavor-singlet distributions, δu(x) + δd(x) and δū(x) + δd(x), are non-zero only in next-to-leading order. The transversity quark and antiquark distributions are found to be significantly different from the longitudinally polarized distributions ∆u(x)±∆d(x) and ∆ū(x)±∆d(x), respectively, in contrast to the prediction of the naive non-relativistic quark model. We show that this affects the predictions for the spin asymmetries in Drell-Yan pair production in transversely polarized pp and pp collisions.1 It is convenient here to define the light-cone vector components using the 1-rather than the 3direction. With this choice the direction of transverse polarization of the nucleon can be chosen as the 3-direction, which will make the expressions in Subsection 3.3 look more conventional.

We investigate three different axial-vector form factors of the nucleon, G 0 A , G 3 A , G 8 A , within the framework of the SU(3) chiral quark-soliton model, emphasizing their strangeness content. We take into account the rotational 1/N c and linear strange quark (m s ) contributions using the symmetryconserving SU(3) quantization and assuming isospin symmetry. The strange axial-vector form factor is also obtained and they all are discussed in the context of the parity-violating scattering of polarized electrons off the nucleon and its relevance to the strange vector form factors.

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The unpolarized spin-flip isoscalar generalized parton distribution function (E u + E d )(x, ξ, t) is studied in the large-Nc limit at a low normalization point in the framework of the chiral quarksoliton model. This is the first study of generalized parton distribution functions in this model, which appear only at the subleading order in the large-Nc limit. Particular emphasis is put therefore on the demonstration of the theoretical consistency of the approach. The forward limit of (E u + E d )(x, ξ, t) of which only the first moment -the anomalous isoscalar magnetic moment of the nucleon -is known phenomenologically, is computed numerically. Observables sensitive to (E u + E d )(x, ξ, t) are discussed.

We investigate parity-violating electroweak asymmetries in the elastic scattering of polarized electrons off protons within the framework of the chiral quark-soliton model (χQSM). We use as input the former results of the electromagnetic and strange form factors and newly calculated SU(3) axial-vector form factors, all evaluated with the same set of four parameters adjusted several years ago to general mesonic and baryonic properties. Based on this scheme, which yields positive electric and magnetic strange form factors with a µ s = (0.08 − 0.13)µ N , we determine the parity-violating asymmetries of elastic polarized electron-proton scattering. The results are in a good agreement with the data of the A4, HAPPEX, and SAMPLE experiments and reproduce the full Q 2 -range of the G0-data. We also predict the parity-violating asymmetries for the backward G0 experiment.1. The complex structure of the nucleon goes well beyond its simplest description as a collection of three valence quarks moving in some potential. The sea of gluons and qq-pairs that arises in quantum chromodynamics is expected to play an important role even at long distance scales. As the lightest explicitely non-valence quark the strange quark provides an attractive tool to probe the qq-sea, since any strange quark contribution to an observable must be the effect of the sea. Thus the strange quark contribution to the distributions of charge and magnetization in the nucleon has been a very important issue well over decades, since it provides a vital clue in understanding the structure of the nucleon. For recent reviews, see, for example, Refs. [1,2,3,4,5]. Recently, the strangeness content of the nucleon has been studied particularly intensively since parity-violating electron scattering (PVES) has demonstrated to provide an essential tool for probing the sea of ss pairs in the vector channel [6,7]. In fact, various PVES experiments have been already conducted in order to measure the parity-violating asymmetries (PVAs) from which the strange vector form factors can be extracted [8,9,10,11,12,13,14,15,16]. While PVES experiments have direct access to the PVA with relatively good precision, a certain amount of uncertanties arise in the flavor decomposition for the nucleon vector form factors. As a result, the strange vector form factors extracted so far from the data have rather large errors [8,9,10,11,12,13,14,15].The chiral quark-soliton model (χQSM) is an effective quark theory of the instantondegrees of freedom of the QCD vacuum. It results in an effective chiral action for valence and sea quarks both moving in a static self-consistent Goldstone background field [17,18] originating from the spontaneous chiral symmetry breaking of the QCD. It has successfully been applied to mass splittings of hyperons, to electromagnetic and axial-vector form factors [17] of the baryon octet and decuplet and to forward and generalized parton distributions [19,20,21] and has led even to the prediction of the heavily discussed pentaquark baryon Θ + [22]. The present aut...

We calculate the ratios E2/M1 and C2/M1 for the electroproduction of the ∆ (1232) in the region of photon virtuality 0 <−q 2 < 1 GeV 2 . The magnetic dipole amplitude M1 is also presented. The theory used is the chiral quark-soliton model, which is based on the instanton vacuum of the QCD. The calculations are performed in flavours SU(2) and SU(3) taking rotational (1/N c ) corrections into account. The results for the ratios agree qualitatively with the available data, although the magnitude of both ratios seems to underestimate the latest experimental results.

The nucleon form factors of the energy-momentum tensor are studied in the large-N c limit in the framework of the chiral quark-soliton model for model parameters that simulate physical situations in which pions are heavy. This allows for a direct comparison to lattice quantum chromodynamics results.