Results 1 - 10 of 5821
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[en] We modify the previous quasi-local mass definition. The new definition provides expressions of the quasi-local energy, the quasi-local linear momentum and the quasi-local mass. And they are equal to the ADM expressions at spatial infinity. Moreover, the new quasi-local energy has the positivity property.
[en] A-entropy is investigated with respect to certain semispectral measures in a given state. It is shown that the entropy with respect to an observable describing 'simultaneous' measurement of positron and momentum is greater than the von Neumann entropy. Similar results are obtained for the fuzzy and sharp positions. The continuity properties of this entropy are also examined. (author)
[en] Deep inelastic neutron scattering measurements on normal liquid 4He at 4.25 K have been carried out at eleven densities between 0.125 (saturated vapor pressure) and 0.200 gm/cm3, at a momentum transfer of 23 /angstrom//sup /minus/1/. A sum of two Gaussians is required to characterize the scattering at all densities, even when the broadening due to instrumental resolution and corrections to the impulse approximation are included. The kinetic energy varies from 15.5 K at 0.125 gm/cm3 to 3.27 K at 0.200 gm/cm3. 24 refs., 9 figs., 2 tabs
[en] The influence of electron spectrometer alignment on the momentum resolution of electron-impact ionisation (e,2e) experiments is quantified. We show that for coplanar measurements with circular detector apertures, the azimuthal spectrometer alignment should be determined with an accuracy of ±0.001 rad to optimise the momentum resolution of an (e,2e) apparatus. Using this criterion, we predict an improvement in the (e,2e) momentum resolution of ∼30% near q=0 a.u., where quantum-mechanical scattering models predict a minimum in the triple differential cross-section (TDCS) of atomic p states. This result will assist in determining an upper limit on the effects of second order scattering processes that contribute to small momentum transfers
[en] The Kennard-type uncertainty relation ΔxΔp > ℎ/2 is formulated for a free particle with given momentum < p> inside a box with periodic boundary conditions in the large box limit. Our construction of a free particle state is analogous to that of the Bloch wave in a periodic potential. A simple Robertson-type relation, which minimizes the effect of the box boundary and may be useful in some practical applications, is also presented. (author)
[en] Experiments at the future linear collider project may answer long-standing questions in elementary particle physics and cosmology, such as what the origin of particle mass is, whether the concept of space-time should be extended, and how the universe was created. We present the technology choice, the optimization process, and the expected performance of the inner trackers currently proposed in the large-detector concept for the future linear collider project.
[en] A single component independent cluster model, based on a certain smoothness property of the amplitudes involved, is presented. The KNO (Koba, Nielsen, Olesen) multiplicity distribution function, the momentum distribution of the leading particles and clusters, as well as the relations among them are deduced
[en] In this study, we have calculated energy, energy-flux and momentum of the Goedel-type wormholes, both static and rotating universe model and allowing to travel in time by means of closed timelike curved. It is obtained that energy of the Goedel-type wormholes is different from zero but momentum of the Goedel-type wormholes is zero. In addition to these quantities , we have obtained that the two components of the energy-flux density are zero, the other one is different from zero. Finally, these results have been discussed.