Importance of the direct knockout mechanism in relativistic calculations for (γ,p) reactions

Abstract

Results of relativistic calculations of the direct knockout (DKO) mechanism for the photon induced removal of a proton from a target nucleus over a wide range of energies and nuclei are presented. Spectroscopic factors used in the calculations are fixed from consistent * This work was supported in part by the Natural Sciences and Engineering Research Council of Canada.analyses of the quasifree electron scattering process (e, e ′ p). The results indicate that within the uncertainties of the model, the knockout contributions are generally close to the experimental data for missing momenta below ≈ 500 MeV/c. This is in disagreement with nonrelativistic analyses which often find that the direct knockout contribution can be quite small compared to the data and that meson exchange corrections can be important. The present study suggests that meson exchange current contributions may not be as large when treated in a relativistic framework. We also point out some difficulties we encountered in analyzing the data for a 12 C target at photon energies below 80 MeV.

Mechanically generating entangled photons from the vacuum: A microwave circuit-acoustic resonator analog of the oscillatory Unruh effect

“…Quantum correlated photon pair production can be verified through for example quantum squeezing (so-called "two-mode" squeezing) or quantum entanglement measures (e.g., logarithmic negativity-see Sec. IV) of the n = 1, 2 cavity-detector resonator normal modes [8]. In the remainder of this section, we analyze the two-mode squeezing and briefly discuss how it may be measured.…”

“…One approach to circumventing the extreme relativistic speed requirement is to realize analogue systems [4], which are described by quantum dynamical equations that closely match those for the actual DCE and UE. For example, the accelerating mechanical mirror or photodetector may be replaced by an electromagnetically induced, time changing boundary condition [5][6][7][8] or detector coupling [9,10], such that the quantum electromagnetic field vacuum responds effectively in the same way as in the original DCE and UE.…”

Total and Differential Cross-Sections of 16O(γ,n)3Heα8Be0 Reaction

“…Визнано, що основний внесок дає процес взаємодiї -кванта з нуклонною парою в момент обмiну нуклонiв мезоном. Але цi висновки не збiгаються з розрахунками в релятивiстському наближеннi [5,6]. На прикладi декiлькох ядер було показано, що внесок в ( , )-реакцiю вiд прямого механiзму значно бiльше, нiж у нерелятивiстсько-му наближеннi, i узгоджується з експериментом.…”

Enhanced Dynamic Casimir Effect in Temporally and Spatially Modulated Josephson Transmission Line

“…[10] Various solutions have been theoretically proposed to achieve this rapid modulation of the cavity resonances, for example, by using laser or magnetic field to modulate the reflection property of the semiconductor [11,12] or superconducting [13] mirror, or through non-adiabatic temporal modulation of the light-matter coupling strength [14][15][16] in cavity QED systems, or by using modulation of nonlinear materials, [17] cold matter material, [18] or superconductor circuits [19] to vary the refractive index of the filler inside the cavity. Recently, by using SQUID-based circuits, [19][20][21][22][23][24][25][26] the effective length or refraction property of a cavity was tuned by modulating the effective inductance through a time-varying magnetic flux at very high frequencies (>10 GHz), leading to experimental observation of squeezing signals of DCE in the microwave regime, which verified the theoretical prediction.…”