Radiative Corrections for Pion Polarizability Experiments

We use the semi-analytical program RCFORGV to evaluate radiative corrections to one-photon radiative emission in the high-energy scattering of pions in the Coulomb field of a nucleus with atomic number Z. It is shown that radiative corrections can simulate a pion polarizability effect. The average effect was estimated for pion energies 40-600 GeV. We also study the range of applicability of the equivalent photon approximation in describing one-photon radiative emission.Comment: 11 pages (LaTex), 6 figures, 1 table. No changes in the paper. New submission because old files are corrupted in arXi

Experimental study of the e+e- -> pi0 gamma process in the energy region sqrt(s)=0.60-0.97 GeV

Results of the study of the e+e-->pi0 gamma process with SND detector at VEPP-2M collider in the c.m.s. energy range sqrt(s)=0.60-0.97 GeV are presented. Using 36513 selected events corresponding to a total integrated luminosity of 3.4 pb^-1 the e+e-->pi0 gamma cross section was measured. The energy dependence of the cross section was analyzed in the framework of the vector meson dominance model. The data are well described by a sum of phi,omega,rho0->pi0 gamma decay contributions with measured decay probabilities: Br(omega->pi0 gamma)=(9.34+-0.15+-0.31)% and Br(rho0->pi0 gamma)=(5.15+-1.16+-0.73)*10^-4 . The rho-omega relative interference phase is phi(rho,omega}=(-10.2+-6.5+-2.5) degree

Experimental studies of the nuclear-physical characteristics of the extended uranium target irradiated by relativistic protons, deutrons and ¹²C nuclei

In 2011-2017 in the framework of the international collaboration project “Energy and Transmutation of RAW”, a series of experimental studies on the deep subcritical uranium assembly QUINTA were carried out. The massive uranium target (512 kg of ⁿᵃᵗU) was irradiated with 0.66 GeV proton, deuterons and ¹²C nuclei (1 to 4 AGeV) from the Phasotron and Nuclotron accelerators (JINR, Dubna). The main results of experimental studies carried out with the participation of the Kharkov group of collaboration are presented.У 2011-2017 рр. у рамках Міжнародної колаборації «Енергія і трансмутація РАВ» було проведено серію експериментальних досліджень на глибоко підкритичній урановій збірці «КВІНТА». Масивна уранова мішень (512 кг ⁿᵃᵗU) збірки опромінювалася 0,66 ГеВ протонами, дейтронами і ядрами ¹²С (1…4 ГеВ/нукл.) від прискорювачів Фазотрон і Нуклотрон (ОІЯД, м. Дубна). Наведено основні результати експериментальних досліджень, які було виконано за участю харківської групи колаборації.В 2011-2017 гг. в рамках Международной коллаборации «Энергия и трансмутация РАО» была проведена серия экспериментальных исследований на глубоко подкритической урановой сборке «КВИНТА». Массивная урановая мишень (512 кг ⁿᵃᵗU) сборки облучалась 0,66 ГэВ протонами, дейтронами и ядрами ¹²С (1…4 ГэВ/нукл.) от ускорителей Фазотрон и Нуклотрон (ОИЯИ, г. Дубна). Представлены основные результаты экспериментальных исследований, выполненных при участии харьковской группы коллаборации

Measurement of RudsR_{\text{uds}} and RR between 3.12 and 3.72 GeV at the KEDR detector

Using the KEDR detector at the VEPP-4M $e^+e^-$ collider, we have measured the values of $R_{\text{uds}}$ and $R$ at seven points of the center-of-mass energy between 3.12 and 3.72 GeV. The total achieved accuracy is about or better than $3.3\%$ at most of energy points with a systematic uncertainty of about $2.1\%$. At the moment it is the most accurate measurement of $R(s)$ in this energy range

New precise determination of the \tau lepton mass at KEDR detector

The status of the experiment on the precise $\tau$ lepton mass measurement running at the VEPP-4M collider with the KEDR detector is reported. The mass value is evaluated from the $\tau^+\tau^-$ cross section behaviour around the production threshold. The preliminary result based on 6.7 pb$^{-1}$ of data is $m_{\tau}=1776.80^{+0.25}_{-0.23} \pm 0.15$ MeV. Using 0.8 pb$^{-1}$ of data collected at the $\psi'$ peak the preliminary result is also obtained: $\Gamma_{ee}B_{\tau\tau}(\psi') = 7.2 \pm 2.1$ eV.Comment: 6 pages, 8 figures; The 9th International Workshop on Tau-Lepton Physics, Tau0

Measurement of \Gamma_{ee}(J/\psi)*Br(J/\psi->e^+e^-) and \Gamma_{ee}(J/\psi)*Br(J/\psi->\mu^+\mu^-)

The products of the electron width of the J/\psi meson and the branching fraction of its decays to the lepton pairs were measured using data from the KEDR experiment at the VEPP-4M electron-positron collider. The results are \Gamma_{ee}(J/\psi)*Br(J/\psi->e^+e^-)=(0.3323\pm0.0064\pm0.0048) keV, \Gamma_{ee}(J/\psi)*Br(J/\psi->\mu^+\mu^-)=(0.3318\pm0.0052\pm0.0063) keV. Their combinations \Gamma_{ee}\times(\Gamma_{ee}+\Gamma_{\mu\mu})/\Gamma=(0.6641\pm0.0082\pm0.0100) keV, \Gamma_{ee}/\Gamma_{\mu\mu}=1.002\pm0.021\pm0.013 can be used to improve theaccuracy of the leptonic and full widths and test leptonic universality. Assuming e\mu universality and using the world average value of the lepton branching fraction, we also determine the leptonic \Gamma_{ll}=5.59\pm0.12 keV and total \Gamma=94.1\pm2.7 keV widths of the J/\psi meson.Comment: 7 pages, 6 figure

Search for narrow resonances in e+ e- annihilation between 1.85 and 3.1 GeV with the KEDR Detector

We report results of a search for narrow resonances in e+ e- annihilation at center-of-mass energies between 1.85 and 3.1 GeV performed with the KEDR detector at the VEPP-4M e+ e- collider. The upper limit on the leptonic width of a narrow resonance Gamma(R -> ee) Br(R -> hadr) < 120 eV has been obtained (at 90 % C.L.)

Measurement of main parameters of the \psi(2S) resonance

A high-precision determination of the main parameters of the \psi(2S) resonance has been performed with the KEDR detector at the VEPP-4M e^{+}e^{-} collider in three scans of the \psi(2S) -- \psi(3770) energy range. Fitting the energy dependence of the multihadron cross section in the vicinity of the \psi(2S) we obtained the mass value M = 3686.114 +- 0.007 +- 0.011 ^{+0.002}_{-0.012} MeV and the product of the electron partial width by the branching fraction into hadrons \Gamma_{ee}*B_{h} = 2.233 +- 0.015 +- 0.037 +- 0.020 keV. The third error quoted is an estimate of the model dependence of the result due to assumptions on the interference effects in the cross section of the single-photon e^{+}e^{-} annihilation to hadrons explicitly considered in this work. Implicitly, the same assumptions were employed to obtain the charmonium leptonic width and the absolute branching fractions in many experiments. Using the result presented and the world average values of the electron and hadron branching fractions, one obtains the electron partial width and the total width of the \psi(2S): \Gamma_{ee} =2.282 +- 0.015 +- 0.038 +- 0.021 keV, \Gamma = 296 +- 2 +- 8 +- 3 keV. These results are consistent with and more than two times more precise than any of the previous experiments

Light Front Formalism for Composite Systems and Some of Its Applications in Particle and Relativistic Nuclear Physics

Light front formalism for composite systems is presented. Derivation of equations for bound state and scattering problems are given. Methods of constructing of elastic form factors and scattering amplitudes of composite particles are reviewed. Elastic form factors in the impulse approximation are calculated. Scattering amplitudes for relativistic bound states are constructed. Some model cases for transition amplitudes are considered. Deep inelastic form factors (structure functions) are expressed through light front wave functions. It is shown that taking into account of transverse motion of partons leads to the violation of Bjorken scaling and structure functions become square of transverse momentum dependent. Possible explanation of the EMC-effect is given. Problem of light front relativization of wave functions of lightest nuclei is considered. Scaling properties of deuteron, ${}^3He$ and ${}^4He$ light front wave functions are checked in a rather wide energy range.Comment: Review paper, Submitted to Phys. Rep., 89 pages, 23 figure