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In 2002 we started experiments with the
universal magnetic detector KEDR at the e+e- collider
VEPP-4M in the Budker institute of nuclear physics in Novosibirsk.
The detector designed to operate in a wide energy region accessible to
VEPP-4M, 2E = 2-11 GeV.
Especially interest for research
represent psi and upsilon families with rich physics.
KEDR is one of 2 large detectors, operating now in this region,
in the world. Unlike other experiments, in the KEDR experiment
the precision calibration of energy of beams
by means of the resonant depolarization method (accuracy ~0.001%) and
the method of Compton backscattering (accuracy ~0.003%) is used.
This, in particular, gives us possibility to perform measurements of
masses of elementary particles with high precision.
Until 2018 experiments with the detector were carried out
in the energy region of psi-mesons.
In the experiments we performed the most precise
measurement of masses of J/psi-meson and psi'-meson (2015),
charged D-meson (2010), and, with the
world average accuracy, tau-lepton (2007).
After our experiments the masses of J/psi-meson
and psi'-meson which are the base of the psi-family spectroscopy
entered the top ten most precise measurements of masses of
elementary particles. Precise knowledge of the masses of narrow J/psi-meson
and psi'-meson is also important to the calibration of accelerators and
detectors in this energy region.
Masses of psi(3770)-meson and neutral D-meson were measured
with accuracy, comparable with accuracy of the best experiments.
We also have measured some other parameters listed psi-mesons,
have performed search for narrow resonances and measurement of the quantity R.
Collection of statistics and data processing are in progress.
From 2018 to 2020, the experiments were carried out in the 2E region from
4.6 to 7 GeV in order to accurately measure R. Further plans of the KEDR
experiment include a transition to the energy range of upsilon mesons in
order to measure their masses and lepton widths. In this area, statistics
will also be collected to study two-photon reactions.
In two-photon physics we plan
to carry out new measurements of
two-photon widths
of known C-even resonances, to measure with
high precision the total
cross-section of two-photon hadron
production, and to perform a search
for new states.
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