Lecturer: Dr. Vladimir Dmitriev
Affiliation: Budker Institute of Nuclear Physics,
Novosibirsk, Russia
Abstract:
In the process $e^+e^- \rightarrow p\bar{p}$,
measured by BABAR (SLAC) and later on by
CMD3 (BINP) collaborations, several
unexpected features have been observed. First,
a very rapid growth of the cross section near
threshold, faster than just s-wave contribution.
Second, a strong energy dependence of the
ratio $|G_E(q^2)/G_M(q^2)|$ of the proton
electromagnetic form factors in a rather narrow
region of energy near threshold. Third, the
energy dependence of the cross section is
rather flat below 200 MeV in c.m. and starts to
fall above this energy. We found that these
effects can be explained by the influence of the
final state interaction between slow moving
nucleon and antinucleon. The final state
interaction can be described by an optical
potential. The imaginary part of the optical
potential describes the process of nucleon-
antinucleon annihilation into pions. Therefore,
there is a contribution to the cross section of
$e^+e^- \rightarrow$ hadrons via production of
virtual $N\bar{N}$ with subsequent annihilation
into mesons. Calculating this contribution one
can obtain some restrictions on the imaginary
part of $N\bar{N}$ optical potential.
Additional details of the upcoming Israeli
Joint Nuclear Physics' Seminars can be
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