References - Bogoliubov Laboratory of Theoretical Physics - JINR

Figure 1: a)[left] μpG p
E /Gp M (hard and dot-dashed lines correspond to variant (I) and (II)); b)[right]
(hard and dot-dashed lines corresponds to variant (II) and (I));
G n E /Gn M
with the standard normalization of the form factors κ1 = 1.53 and κ2 = 0.31. The
size of the parameter m =0.4 was determined by the low t experimental data; the free
parameters a± (a+ -forH and a− -forE) were chosen to reproduce the experimental
data in a wide t region. The q(x) was taken from the MRST2002 global fit [10] with the
scale μ 2 =1GeV 2 . In all our calculations we restrict ourselves, as in other works, only
to the contributions of u and d quarks and the terms in H q and E q .
2 Proton and neutron electromagnetic form factors
The proton Dirac form factor calculated in [7,9] reproduces sufficiently well the behavior
of experimental data not only at high t but also at low t. Our description of the ratio of the
Pauli to the Dirac proton form factors and the ratio of G p
E /Gp M shows (see Fig.1a) that in
our model we can obtain the results of both the methods (Rosenbluth and Polarization)
by changing the slope of E [9]. Based on the model developed for proton the neutron
form factors are calculated too. To do this the isotopic invariance can be used to change
the proton GPDs to neutron GPDs. The calculations of Gn E and GnM (see Fig.1b) show
that the variant which describes the polarization data is in better agreement with the
experimental data that is coincides with our calculations.
3 Transversety asymmetry of the gravitational form
factors
The representation (2)combined with our model (we use here the first variant of parameters
describing the experimental data obtained by the polarization method) allows to
calculate the gravitational form factors of valence quarks and their contribution (being
just their sum) to gravitational form factors of nucleon [8, 9]. Note that nonperturbative
analysis within the framework of the lattice OCD indicates that the net quark contribution
to the anomalous gravimagnetic moment Bu+d(0)is close to zero [11, 12]. Let us
examine the distribution of matter (that is, gravitational charge) in the polarized nucleon.
For that purpose we generalize (4) in a straightforward way and introduce the
119