The specificity of searches for W′W^{\prime}, Z′Z^{\prime} and γ′\gamma^{\prime} coming from extra dimensions

We discuss the specificity of searches for hypothetical $W^{\prime}$, $Z^{\prime}$ and $\gamma^{\prime}$ bosons at hadron colliders in single top quark and $\mu^{+}\nu_{\mu}$ production and Drell-Yan processes assuming these particles to be the Kaluza-Klein excitations of the gauge bosons of the Standard Model. In this case any process mediated by $W$ is also mediated by the whole KK tower of its excitations, whereas to the processes mediated by $Z$ and $\gamma$ there is not only a contribution from their KK towers, but also from that of the graviton. The contributions of the towers above $W^{\prime}$, $Z^{\prime}$ and $\gamma^{\prime}$ and above the first excitation of the graviton are included with the help of effective four-fermion Lagrangians. We compute the cross-sections of these processes taking into account the contributions of the Standard Model gauge bosons, of their first KK modes and of the corresponding KK towers and discuss the impact of the interference between them. For pp-collisions at the LHC with the center of mass energy 14 TeV we found specific changes of the distribution tails due to the interference effects. Such a modification of distribution tails is characteristic for the processes mediated by particles coming from extra dimensions and should always be taken into account when looking for them.Comment: 14 pages, 12 figures, LaTeX. References added, figures added, text enlarge

Comparative Study of Multifragmentation of Gold Nuclei Induced by Relativistic Protons, 4^4He, and 12^{12}C

Multiple emission of intermediate-mass fragments has been studied for the collisions of p, $^4$He and $^{12}$C on Au with the $4\pi$ setup FASA. The mean IMF multiplicities (for the events with at least one IMF) are saturating at the value of $2.2\pm0.2$ for the incident energies above 6 GeV. The observed IMF multiplicities cannot be described in a two-stage scenario, a fast cascade followed by a statistical multifragmentation. Agreement with the measured IMF multiplicities is obtained by introducing an intermediate phase and modifying empirically the excitation energies and masses of the remnants. The angular distributions and energy spectra from the p-induced collisions are in agreement with the scenario of ``thermal'' multifragmentation of a hot and diluted target spectator. In the case of $^{12}$C+Au(22.4 GeV) and $^4$He(14.6 GeV)+Au collisions, deviations from a pure thermal break-up are seen in the energy spectra of the emitted fragments, which are harder than those both from model calculations and from the measured ones for p-induced collisions. This difference is attributed to a collective flow.Comment: 33 pages 15 figures, accepted in Nucl. Phys.

ACCURACY EVALUATION FOR THE NON-CONTACT DEFECT AREA MEASUREMENT AT THE COMPLEX-SHAPE SURFACES UNDER VIDEOENDOSCOPIC CONTROL

The problem of non-contact surface defect area measurement at complex-shape objects under videoendoscopic control is considered. Major factors contributing to the measurement uncertainty are analyzed for the first time. The proposed method of accuracy analysis is based on the evaluation of 3D coordinates of surface points from 2D projections under assumption of projective camera model and Mahalanobis distance minimization in the image plane. Expressions for area measurement error caused by sum-of-triangles approximation are obtained analytically for practically important cases of cylindrical and spherical surfaces. It is shown that the magnitude of this error component for a single triangle does not exceed 1% for the real values of parameters of the endoscopic imaging system. Expressions are derived for area measurement uncertainty evaluation on arbitrary shape surfaces, caused by measurement errors of 3D coordinates of individual points with and without a priori information about surface shape. Verification of the obtained expressions with real experiment data showed that area measurement error for a complex figure, given by a set of points, is mainly caused by ignoring the fact that these points belong to the surface. It is proved that the use of a priori information about investigated surface shape, which is often available from the design documentation, in many cases would radically improve the accuracy of surface defects area measurement. The presented results are valid for stereoscopic, shadow and phase methods of video endoscopic measurements and can be effectively used in development of new non-contact measuring endoscopic systems and modernization of existing ones

Applicability of Heavy Ion Beam Probing (HIBP) system for stellarator WEGA

The applicability of the HIBP for stellarator WEGA is described in this article. It is possible to use such diagnostics for local plasma parameters measurement. Calculations of probing Na + beam trajectories were done for WEGA magnetic configuration with B0 = 0.5 T. The trajectory optimization aiming for the maximal plasma observation was done for chosen entrance and exit port combination. The calculation showsthat HIBPallows getting radial profiles of plasma parameters. The detector line of equal entrance angle connects the central area and the edge of the plasma column for beam energy E =30-60 keV. The detector line of equal energy E = 40 keV allowsto obtain series of radial profiles during single shot by changing of the beam entrance angle with the scan of control voltage.У статті описана можливість застосування HIBP діагностики для стеларатора WEGA. Можливе застосування цієї діагностики для локального вимірювання параметрів плазми. Проведені розрахунки траєкторій пучка іонів натрію для магнітної конфігурації WEGA з Bo = 0.5 T. Проведено оптимізацію траєкторій з метою одержання максимально можливої області спостерігання плазми для даної комбінації вхідного та вихідного портів. Розрахунки показують можливість одержання радіальних профілів параметрів плазми за допомогою HIBP діагностики. Детекторна лінія для постійного кута входу торкается центральної області та периферії плазми при енергії пучка E =30-60 keV. Детекторна лінія для постійної енергії E = 40 keV дозволяє одержати серію радіальних профілів за один постріл при зміні вхідного кута за допомогою сканування пучка керуючою напругою.В статье описана возможность применения HIBP диагностики для стелларатора WEGA. Возможно применения этой диагностики для локальных измерений параметров плазмы. Проведены расчеты траекторий пучка ионов натрия для магнитной конфигурации WEGA с Bo = 0.5 T. Проведена оптимизация траекторий с целью получения максимально возможной области наблюдения плазмы при данной комбинации входного и выходного портов. Расчеты показывают возможность получения радиальных профилей параметров плазмы с помощью HIBP диагностики. Детекторная линия для постоянного угла входа касается центральной области и периферии плазмы при энергии пучка E =30-60 keV. Детекторная линия для постоянной энергии E = 40 keV позволяет получить серию радиальных профилей за один разряд при изменении входного угла с помощью сканирования пучка управляющим напряжением