**Title**

**Summary**

We have used
Chiral Quark-Soliton Model to study the structure and static properties
of light baryons, i.e. those
made of u, d and s quarks, in their fundamental state. This model has
already demonstrated is efficiency by predicting numbers for physical
quantities quite close to experimental values, and requiring only a few
parameters. This is in fact the only model based on the idea of
constituent quark, respecting approximate chiral symmetry of QCD and
Lorentz invariance, and providing in some way an interpolation picture
between Naive Quark Model (no meson

field) and Skyrme Model (no quarks).

The usual approach to this model is to consider that the
(self-consistent) mean chiral field (soliton) binding quarks is slowly
rotating. While this approximation is justified for ordinary baryons, i.e. those that can be described by
three valence quarks only, it becomes questionable for exotic ones, in
particular pentaquarks, i.e.
those that need at least five quarks to be described. These exotic
baryons seems to have, from a theoretical point of view, very unusual
properties, e.g. a very small
decay width. From the experimental point of view, the question is quite
involved and rather fuzzy and no definitive conclusion can be inferred.
That is why it was necessary to check if the theoretical prediction for
such a small width was not an artefact due to theapproximation.

Two years ago, Chiral Quark-Soliton Model has been formulated on the
light cone. This compeltely new approach allows one to study the

model within different approximations. For example, It was possible to
consider exact rotations for
the chiral soliton. In compensation, the contribution coming from the
distortion of Dirac sea due to this chiral soliton can no more be
treated exactly. This contribution is expanded in Fock space, i.e. we have considered wave
functions with explicitly three, five and even seven quarks. Within
this approach, we have studied static properties and structure of light
baryons. For this purpose, we have systematically computed all vector,
axial and tensor charges, and magnetic moments. These quantities
provide us with valuable information concerning the nature and
distribution of effective degrees of freedom within

baryons. They also account for the distribution of angular momentum on
the different degrees of freedom and for the baryon shapes.

The
light-cone approach consists of determining and computing the shape of baryon wave functions. Chiral
Quark-Soltion Model provides
a particularly elegant description since, beside respecting fundamental symmetries of QCD, it
describes collectively all light baryons as collective rotational
excitations of the very same
object: chiral soltion. Once these wave functions are known, the different charges are obtained by
sandwiching the corresponding
current operator between baryon states. Furthermore, the model allows one to split charges into
individual flavor, valence and
non-valence contributions. Numerous result have therefore been obtained. Despite the invoked
approximation of flavor SU(3)
symmetry, many of these results are in excellent agreement with experimental data. Disagreements seem
mainly due to the fact that
flavor SU(3) symmetry is in fact broken in nature. The study of these charges being done systematically,
lots of prediction have been
obtained concerning properties and structure of light baryons which have not been measured hitherto.

Among the conclusions of these
researches, we have confirmed that pseudoscalar mesons and relativity are
essential ingredients to
describe correctly static properties and structure of light baryons. We have also observed some explicit signature indicating the quadrupolar distortion of baryons due to
pseudoscalar mesons. This
signature is directly observable is some transitions, e.g. nucleon-to-Delta photoexcitation, i.e. quadrupolar electric

transition. Pentaquark width has
been estimated to a few MeV,
confirming thus previous estimations. Moreover, a qualitative explanation for such a small width is
proposed and is based on the
fact that on the light cone and in the Drell-Yan-West frame, i.e.
current four-vector has not time component), a

pentaquark cannot decay in the
dominant three-quark nucleon sector. This relation between the weight
associated to the dominant
three-quark nucleon sector and pentaquark width has been tested and confirmed in various approximations.

Finally, let us note that for baryon
wave functions projected on
Fock components to be computed, the spin-flavor part has been computed. Since in the model baryons are
generated by the quantization of rotations of the mean chiral field,
this spin-flavor structure is
uniquely fixed by the soliton symmetry. For the very first time, a spin-flavor wave function
for three, five and seven
quarks has been obtained with Clebsh-Gordan coefficients fixed. The three quark spin-flavor wave function
matches exactly to the
well-known non-relativistic SU(6) one. Fock states with higher number of quarks do not respect SU(6)
symmetry and are required for
a relativistic description. We have observed that these higher Fock contributions improve further the
agreement between theoretical
prediction and experimental knowledge.