共查询到20条相似文献,搜索用时 0 毫秒
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《Physics letters. [Part B]》1987,199(1):34-36
The gravitational properties of a long, straight superconducting string are discussed. It turns out that a light ray is deflected through an angle which depends on the total energy per unit length whereas the gravitational force on a test particle depends on the electromagnetic energy in the string. 相似文献
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Diego D. Harari
Vladimir D. Skarzhinsky
《Physics letters. [Part B]》1990,240(3-4):322-326We show that many elementary particle physics processes, such as pair production by a high energy photon, that take place in Minkowski space only if a non-uniform external field provides for momentum non-conservation, do occur in the space-time around a straight cosmic string, even though the space is locally flat and there is no local gravitational potential. We exemplify this mechanism through the evaluation of the cross section per unit length of string for the decay of a massless scalar particle into a pair of massive particles. The cross sections for this kind of processes are typically small. Nevertheless, it is interesting to realize how these reactions occur due to topological properties of space, rather than to the action of a local field. 相似文献
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There is shown to be a nonzero effect during the measurement of the time lag in a Michelson interferometer in the earth's gravitational field, for vertical positioning of one of the arms. A formula for calculating the time lag is obtained. The possibility of measuring the interferometer effect with the aid of fiber optics is considered.S. Ordzhonikidze Moscow Aviation Institute. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 3, pp. 95–97, March, 1993. 相似文献
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Primordial gravitational waves (GWs) with frequencies > or approximately equal to 10(-15) Hz contribute to the radiation density of the Universe at the time of decoupling of the cosmic microwave background (CMB). This affects the CMB and matter power spectra in a manner identical to massless neutrinos, unless the initial density perturbation for the GWs is nonadiabatic, as may occur if such GWs are produced during inflation or some post-inflation phase transition. In either case, current observations provide a constraint to the GW amplitude that competes with that from big-bang nucleosynthesis (BBN), although it extends to much lower frequencies (approximately 10(-15) Hz rather than the approximately 10(-10) Hz from BBN): at 95% confidence level, omega(gw)h(2) 相似文献
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We derive the primordial power spectrum of density fluctuations in the framework of quantum cosmology. For this purpose we perform a Born-Oppenheimer approximation to the Wheeler-DeWitt equation for an inflationary universe with a scalar field. In this way, we first recover the scale-invariant power spectrum that is found as an approximation in the simplest inflationary models. We then obtain quantum gravitational corrections to this spectrum and discuss whether they lead to measurable signatures in the cosmic microwave background anisotropy spectrum. The nonobservation so far of such corrections translates into an upper bound on the energy scale of inflation. 相似文献
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O. S. Sazhina M. V. Sazhin V. N. Sementsov 《Journal of Experimental and Theoretical Physics》2008,106(5):878-887
A method of searching for cosmic strings based on an analysis of the cosmic microwave background (CMB) anisotropy is presented. A moving straight cosmic string is shown to generate structures of enhanced and reduced brightness with a distinctive shape. The conditions under which a string can be detected by both CMB anisotropy and gravitational lensing in optical surveys are analyzed. For a relativistic string with a deficit angle of ~1″–2″, the amplitude of the generated anisotropy is shown to be ~15–30 μK. 相似文献
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V. V. Gonyaev 《Russian Physics Journal》1977,20(4):421-424
A simple method is proposed for the measurement of the fundamental kinematic characteristics of a particle falling freely in a stationary gravitational field near an observer whose world line is the trajectory of a group of motions. An expression is obtained for the observable acceleration on the world line of the observer, and some particular cases are considered. In the concluding section the results of a previous paper by the author are reviewed.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 4, pp, 7–13, April, 1977. 相似文献
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《Physics letters. [Part B]》1987,194(1):59-62
We investigate the effect of duality transformations on the geometries of a subclass of two-dimensional non-linear sigma-models. We identify the torsion which appears on dualizing such a model, initially without Wess-Zumino-Witten term, as the field strength of the gauge connection appearing in a Kałuza-Klein interpretation of the initial geometry. We show that duality preserves quantum conformal invariance at order [α′]0, where α′ is the string tension parameter, provided the change induced in the geometry by duality is accompanied by a shift in the dilaton field. We interpret these combined transformations as a symmetry of the order [α′]0 string background field equations. 相似文献
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M. Diakonou K. Farakos G. Koutsoumbas E. Papantonopoulos 《Physics letters. [Part B]》1990,240(3-4):351-355
We derive the quantum constraint algebra for a closed bosonic string moving in a gravitational and dilaton background to first order in '. The hamiltonian approach is used to directly compute the quantum constraint commutators and calculate the c-and q-number anomalies that arise at the quantum level. The requirement that the algebra preserves the conformal invariance leads to the known background field equations. 相似文献
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Emilio Santos 《General Relativity and Gravitation》1993,25(7):717-720
From the equation of continuity, an equation is derived for the change in the spectrum of radiation stationary in a static gravitational field, as measured by local observers in their proper frame. It is shown that an isotropic solution always exists in which the energy density per unit frequency interval is
3 times an arbitrary function of
. 相似文献