On the Parameters of the QCD-Motivated Potential in the Relativistic Independent Quark Model

In the framework of the relativistic independent quark model the parameters of the QCD-motivated static potential and the quark masses are calculated on the basis of the $1^{--}$ meson mass spectra. The value of the confining potential coefficient is found to be ($0.197\pm 0.005) GeV${}^2$. for quark- antiquark interaction independently on their flavours. The dependence of the quasi-Coulombic potential strength on the interaction distance are consistent with the QCD-motivated behaviour. The$q\bar q$-separations are evaluated and the$e^+e^-$ decay widths are estimated with the help of relativistic modification of the Van Royen-Weisskopf formula.Comment: 10 pages, LaTex; added references for the beginning, changed the last paragraph at the end, made a few stylistic correction

Superconducting 63-pole 2 Tesla wiggler for Canadian Light Source

A superconducting 63-pole wiggler with the average period 34 mm designed and fabricated at the Institute of Nuclear Physics in Novosibirsk for Synchrotron Radiation Center (CLS) in Canada is described. The maximum field 2.2 Tesla in the median plane has been achieved. The liquid helium consumption less than 0.03 liters per hour in operating mode has been reached. In January 2005, the wiggler was installed in the storage ring in CLS and now experiments are already underway. The main parameters of the magnet and the cryogenic systems as well as test results are presented.Описан 63-полюсный сверхпроводящий вигглер со средним периодом 34 мм, изготовленный в ИЯФ СО РАН для центра синхротронного излучения CLS в Канаде. Получено максимальное поле в медианной плоскости 2.2 Т. При этом расход жидкого гелия в рабочем режиме менее 0.03 литра в час. Вигглер установлен на накопительное кольцо CLS и ведутся эксперименты с СИ. Приведены основные параметры магнитной и криогенной систем.Описаний 63-полюсний надпровідний вігглер із середнім періодом 34 мм, виготовлений в ІЯФ СО РАН для центра синхротронного випромінювання CLS у Канаді. Отримано максимальне поле в медіанній площині 2.2 Т. При цьому витрата рідкого гелію в робочому режимі менш 0.03 літра в годину. Вігглер установлений на накопичувальне кільце CLS і ведуться експерименти із СІ. Наведено основні параметри магнітної й криогенної систем

Superconducting high-field wigglers and wave length shifters in Budker INP

Several high-field superconducting wigglers (SCW) and wavelength shifters (WLS) are fabricated in the Budker INP for generation of synchrotron radiation. Three-pole WLS with the magnetic field of 7.5 T are installed on LSU‑CAMD and BESSY-II storage rings for shifting the radiation spectrum. WLS with the field of 10.3 T will be used for generation of slow positrons on SPring-8. Creation of a 13-pole 7 T wiggler for the BESSY-II and 45-pole 3.5 T wiggler for ELETTRA now is finished. The main characteristics, design features and synchrotron radiation properties of SCW and WLS created in the Budker INP are presented in this article

Spin Effects in Two Quark System and Mixed States

Based on the numeric solution of a system of coupled channels for vector mesons ($S$- and $D$-waves mixing) and for tensor mesons ($P$- and $F$-waves mixing) mass spectrum and wave functions of a family of vector mesons $q\bar{q}$ in triplet states are obtained. The calculations are performed using a well known Cornell potential with a mixed Lorentz-structure of the confinement term. The spin-dependent part of the potential is taken from the Breit-Fermi approach. The effect of singular terms of potential is considered in the framework of the perturbation theory and by a configuration interaction approach (CIA), modified for a system of coupled equations. It is shown that even a small contribution of the $D$-wave to be very important at the calculation of certain characteristics of the meson states.Comment: 12 pages, LaTe

Events in a Non-Commutative Space-Time

We treat the events determined by a quantum physical state in a noncommutative space-time, generalizing the analogous treatment in the usual Minkowski space-time based on positive-operator-valued measures (POVMs). We consider in detail the model proposed by Snyder in 1947 and calculate the POVMs defined on the real line that describe the measurement of a single coordinate. The approximate joint measurement of all the four space-time coordinates is described in terms of a generalized Wigner function (GWF). We derive lower bounds for the dispersion of the coordinate observables and discuss the covariance of the model under the Poincare' group. The unusual transformation law of the coordinates under space-time translations is interpreted as a failure of the absolute character of the concept of space-time coincidence. The model shows that a minimal length is compatible with Lorents covariance.Comment: 13 pages, revtex. Introductory part shortened and some arguments made more clea