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[en] The impact parameter dependence of the disappearance of transverse flow has been investigated using the Michigan State University 4π Array upgraded with the High Rate Array (HRA). The energy at which collective transverse flow in the reaction plane disappears, called the balance energy (bal), is found to increase approximately linearly as a function of impact parameter. Comparison of our measured values of Ebal(b) shows agreement with predictions of Quantum Molecular Dynamics (QMD) model calculations
[en] We discuss a nonperturbative mechanism for generation of the single-spin asymmetries in hadron interactions. It is based on the chiral quark model combined with unitarity and impact parameter picture and provides explanation for the experimental regularities observed under the measurements of the spin asymmetries.
[en] Galaxies are not isolated systems of stars and gas, ''independent universes'' as believed by astronomers about ten years ago, but galaxies are formed and evolve by interaction with their environment, and in particular with their nearest neighbors. Gravitational interactions produce enormous tides in the disk of spiral galaxies, generate spiral arms and trigger bursts of star formation. Around elliptical galaxies, the collision with a small companion produces a series of waves, or shells. A galaxy interaction leads, in most cases, to the coalescence of the two coliders; therefore all galaxies are not formed just after the Big-Bang, when matter recombines: second generation galaxies are still forming now by galaxy mergers, essentially elliptical galaxies, but also compact dwarfs. Collisions between galaxies could also trigger activity in nuclei for radiogalaxies and quasars
[fr]Les galaxies ne sont pas des systemes isoles d'etoiles et de gaz, des ''mondes a part'' comme les astronomes le pensaient il y a une dizaine d'annees, mais elles se forment et evoluent en interagissant avec leur environnement, et en particulier avec leurs plus proches voisines. Les interactions gravitationnelles produisent des marees gigantesques dans le disque des galaxies spirales, engendrent des bras spiraux et provoquent des sursauts de formations d'etoiles. Autour des galaxies elliptiques, la collision avec un petit compagnon forme une serie de vagues, de coquilles. Une interaction se termine le plus souvent par la coalescence des deux protagonistes; ainsi les galaxies ne se seraient pas toutes formees juste apres le ''Big-Bang'', a la recombinaison de la matiere, mais il se formerait encore aujourd'hui des galaxies elliptiques, et meme des galaxies naines compactes. Les collisions entre galaxies pourraient aussi etre responsables de l'activite des noyaux des radiogalaxies et des quasars
[en] We present the results on a new trigger scheme for the selection of short lived particles. These results were obtained in a test run of the WA82 experiment at the CERN Omega spectrometer. We have measured, for charmed particles, an enrichment factor of ≅ 15 over an interaction trigger. (orig.)
[en] Measurements of illuminance during a solar eclipse are presented. The data are compared to theoretical predictions, based on a geometrical model for obscuration. The model assumes a straight and uniform motion of the sun and moon as well as a spherical shape of both, i.e. it neglects any effects of limb darkening. Furthermore, the sun's disk is assumed to have homogeneous luminosity, i.e. any luminosity variations due to sun spots are neglected. Input parameters are the duration of the eclipse, the duration of totality, the impact parameter, i.e. the distance between the two trajectories of sun and moon, and the sizes of sun and moon. The model applies to all types of eclipses, partial, annular and total
[en] Dependence of mean multiplicity on the transversal momentum transfer is studied. In framework of the model in view, based on possible probabilitic interpretation of the unitarity condition, and assuming a weak correlation between the recoil particle momenta in the intermediate n-particle state, it is shown that mean multiplicity increases linearly with rise of the transversal momentum. Behaviour of the mean multiplicity depending on the impact parameter is also studied
[en] Color fluctuations in hadron–hadron collisions are responsible for the presence of inelastic diffraction and lead to distinctive differences between the Gribov picture of high energy scattering and the low energy Glauber picture. We find that color fluctuations give a larger contribution to the fluctuations of the number of wounded nucleons than the fluctuations of the number of nucleons at a given impact parameter. The two contributions for the impact parameter averaged fluctuations are comparable. As a result, standard procedures for selecting peripheral (central) collisions lead to selection of configurations in the projectile which interact with smaller (larger) than average strength. We suggest that studies of pA collisions with a hard trigger may allow to observe effects of color fluctuations
[en] We study the Wigner distributions for a physical electron, which reveal the multidimensional images of the electron. The physical electron is considered as a composite system of a bare electron and photon. The Wigner distributions for unpolarized, longitudinally polarized and transversely polarized electron are presented in transverse momentum plane as well as in impact-parameter plane. The spin–spin correlations between the bare electron and the physical electron are discussed. We also evaluate all the leading twist generalized transverse momentum distributions (GTMDs) for electron.