| 1. |
- Aerts, Sven, et al.
(författare)
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Two-photon Franson-type experiments and local realism
- 1999
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Ingår i: Physical Review Letters. - : American Physical Society. - 0031-9007 .- 1079-7114. ; 83:15, s. 2872-2876
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Tidskriftsartikel (refereegranskat)abstract
- The two-photon interferometric experiment proposed by J. D. Franson [Phys. Rev. Lett. 62, 2205 (1989)] is often treated as a “Bell test of local realism.” However, it has been suggested that this is incorrect due to the 50% postselection performed even in the ideal gedanken version of the experiment. Here we present a simple local hidden variable model of the experiment that successfully explains the results obtained in usual realizations of the experiment, even with perfect detectors. Furthermore, we also show that there is no such model if the switching of the local phase settings is done at a rate determined by the internal geometry of the interferometers.
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| 2. |
- Alexa, L. C., et al.
(författare)
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Measurements of the Deuteron Elastic Structure Function A(Q2) for 0.7≤Q2≤6.0(GeV/c)2 at Jefferson Laboratory
- 1999
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Ingår i: Physical Review Letters. - 1079-7114. ; 82:7, s. 1374-1378
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Tidskriftsartikel (refereegranskat)abstract
- The deuteron elastic structure function A(Q2) has been extracted in the range 0.7≤Q2≤6.0(GeV/c)2 from cross section measurements of elastic electron-deuteron scattering in coincidence using the Hall A Facility of Jefferson Laboratory. The data are compared to theoretical models, based on the impulse approximation with the inclusion of meson-exchange currents, and to predictions of quark dimensional scaling and perturbative quantum chromodynamics.
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| 3. |
- Amaudruz, P, et al.
(författare)
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Gottfried sum from the ratio F2n/F2p
- 1991
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Ingår i: Physical Review Letters. - : American Physical Society. - 0031-9007 .- 1079-7114. ; 66:21, s. 2712-2715
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Tidskriftsartikel (refereegranskat)abstract
- Experimental results obtained at the CERN Super Proton Synchrotron on the structure-function ratio F2n/F2p in the kinematic range 0.004 < x < 0.8 and 0.4 < Q2 < 190 GeV2, together with the structure function F2d determined from a fit to published data, are used to derive the difference F2p(x) - F2n(x). The value of the Gottfried sum integral (F2p - F2n) dx/x = 0.240 +/- 0.016 is below the quark-parton-model expectation of 1/3.
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| 4. |
- Aniol, K. A., et al.
(författare)
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Measurement of the neutral weak form factors of the proton
- 1999
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Ingår i: Physical Review Letters. - 1079-7114. ; 82:6, s. 1096-1100
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Tidskriftsartikel (refereegranskat)abstract
- We have measured the parity-violating electroweak asymmetry in the elastic scattering of polarized electrons from the proton. The kinematic point [ ⟨θlab⟩=12.3° and ⟨Q2⟩=0.48(GeV/c)2] is chosen to provide sensitivity, at a level that is of theoretical interest, to the strange electric form factor GsE. The result, A=−14.5±2.2ppm, is consistent with the electroweak standard model and no additional contributions from strange quarks. In particular, the measurement implies GsE+0.39GsM=0.023±0.034(stat)±0.022(syst)±0.026(δGnE), where the last uncertainty arises from the estimated uncertainty in the neutron electric form factor.
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| 5. |
- Antoine, P, et al.
(författare)
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Attosecond pulse trains using high-order harmonics
- 1996
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Ingår i: Physical Review Letters. - 1079-7114. ; 77:7, s. 1234-1237
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Tidskriftsartikel (refereegranskat)abstract
- We demonstrate that high-order harmonics generated by an atom in intense laser field form trains of ultrashort pulses corresponding to different trajectories of electrons that tunnel out of the atom and recombine. Propagation in an atomic jet allows us to select one of these trajectories, leading to a train of pulses of extremely short duration.
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| 6. |
- Arber, T. D., et al.
(författare)
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Large Larmor Radius Stability of the Z-pinch
- 1994
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 72, s. 2399-
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Tidskriftsartikel (refereegranskat)abstract
- The linear m=0 stability of the z pinch in the collisionless, large ion Larmor radius regime is examined using the Vlasov fluid model. The results reveal a strong equilibrium dependence. The uniform current density equilibrium shows a reduction in growth rate when the average ion Larmor radius is about one-fifth of the pinch radius. However, finite Larmor radius effects cannot in themselves produce a stabilized z pinch.
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| 7. |
- Arber, T. D., et al.
(författare)
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Linear Stability of the High Temperature, Dense Z-pinch
- 1995
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 74, s. 2698-
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Tidskriftsartikel (refereegranskat)abstract
- Results are presented on the linear stability of the collisionless m=1 mode in a dense Z pinch. It is shown that a reduction in growth rate by a factor of about 10 (when compared to the zero Larmor radius result) is possible by initializing the Z pinch with a sufficiently low line density. With the completion of this work we conclude that linear, large Larmor radius effects cannot stabilize the high temperature, dense Z pinch. Such pinches will always exhibit linear m=0 or m=1 instabilities with growth times comparable to the radial Alfvén transit time.
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| 8. |
- Aryasetiawan, F., et al.
(författare)
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Energy loss spectra and plasmon dispersions in alkali metals : Negative plasmon dispersion in Cs
- 1994
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Ingår i: Physical Review Letters. - : American Physical Society. - 0031-9007 .- 1079-7114. ; 73:12, s. 1679-1682
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Tidskriftsartikel (refereegranskat)abstract
- We present ab initio calculations of the energy loss spectra and plasmon dispersions of the alkali metals Na, K, Rb, and Cs within the random phase approximation, including band structure effects and core electrons as well as local field effects, due to inhomogeneity in the induced charge density. Band structure effects are found to cause a negative dispersion in Cs.
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| 9. |
- Aryasetiawan, F., et al.
(författare)
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Multiple Plasmon Satellites in Na and Al Spectral Functions from Ab Initio Cumulant Expansion
- 1996
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Ingår i: Physical Review Letters. - : American Physical Society. - 0031-9007 .- 1079-7114. ; 77:11, s. 2268-2271
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Tidskriftsartikel (refereegranskat)abstract
- The valence photoemission spectra of alkali metals exhibit multiple plasmon satellite structure. The calculated spectral functions within the GW approximation show only one plasmon satellite at too large binding energy. In this Letter we use the cumulant expansion approach to obtain the spectral functions of Na and Al from ab initio calculations including the effects of band structure. The GW spectral functions are dramatically improved and the positions of the multiple plasmon satellites are in very good agreement with experiment while their intensities cannot be explained from intrinsic effects only.
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| 10. |
- Bellini, M, et al.
(författare)
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Temporal coherence of ultrashort high-order harmonic pulses
- 1998
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Ingår i: Physical Review Letters. - 1079-7114. ; 81:2, s. 297-300
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Tidskriftsartikel (refereegranskat)abstract
- We have studied the temporal coherence of high-order harmonics (up to the 15th order) produced by focusing 100 fs laser pulses into an argon gas jet. We measure the visibility of the interference fringes, produced when two spatially separated harmonic sources interfere in the far field, as a function of the time delay between the two sources. In general, we find long coherence times, comparable to the expected pulse durations of the harmonics. For some of the harmonics, the interference pattern exhibits two regions, with significantly different coherence times. These results are interpreted in terms of different electronic trajectories contributing to harmonic generation. [S0031-9007(98)05569-7].
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