
VOLUME 113  ISSUE 9 
PAGE 589

Understanding two slopes in the ) differential cross sections
Yu. A. Simonov
National Research Centre "Kurchatov Institute"  ITEP, 117259 Moscow, Russia
Abstract
Recent experiments have discovered two exponents in the pp elastic
differential cross sections with two different slope parameters,
of the order (1620) GeV^{2} and (44.8) GeV^{2} in the
regions GeV^{2} and
GeV^{2}, respectively. We suggest a simple model of the pp
elastic scattering with two types of particle
exchanges: 1) when the exchanged particle transfers the momentum Q
from a quark of the proton p_{1} to one quark in another proton p_{2},
producing the slope B_{1};
2) when the transfer occurs from two quarks in the p_{1} to two quarks in
the p_{2}, giving the exponent with the slope B_{2}. The resulting
amplitude is proportional to
the product of the form factors of two protons, depending on Q, but
with different coefficients in the cases 1) and 2). Using the only
parameter  the proton
charge radius r^{2}_{ch}= 0.93 fm^{2}, one obtains B_{1} = 16 GeV^{2},
B_{2} = 4 GeV^{2} with the strict value of the ratio,
, independent of r_{ch}. These predictions are
surprisingly close to the data both in the pp and in the
differential cross sections. Comparison
to experimental data and theoretical approaches is discussed, together
with possible implications for the future development of the theory.

