The European Physical Journal D最新文献

Suitably normalized differential probabilities of one-photon emission in external electromagnetic fields are compared to quantify the transit of nonlinear Compton scattering to linear Compton scattering, described by the Klein–Nishina formula, and to constant-crossed field treatment. The known Klein–Nishina suppression at large energies is further enforced by increasing field intensity. In view of the Ritus–Narozhny conjecture, we demonstrate that different paths in the field intensity versus energy plane toward large values of the quantum nonlinearity parameter (chi ) facilitate significantly different asymptotic dependencies, both in the Klein–Nishina regime and the constant-crossed field regime and in between.

Differential perspective on the Klein-Nishina effect in strong-field QED: showing the smooth transition from the constant-crossed field (CCF) through the infinite plane-wave approximation (IPA) to the linear Klein-Nishina limit, highlighting the asymptotic behavior of the differential cross sections.

Oscillator strengths and cross sections of the valence-shell excitations in trichlorofluoromethane CFCl(_{3}) are of great importance in plasma etching and monitoring the greenhouse effect. In this work, the valence-shell excitations of CFCl(_{3}) have been studied by an angle-resolved electron energy loss spectrometer operated at a collision energy of 1.5 keV with an energy resolution of about 80 meV. Generalized oscillator strengths of the electronically excited states have been determined at an absolute scale by applying the crossed-beam based on the relative flow technique. The behaviors of generalized oscillator strengths of the valence shell excitations of CFCl(_{3}) have been analyzed. By extrapolating the generalized oscillator strengths to the zero limit of squared momentum transfer, the optical oscillator strengths have been obtained. The BE-scaled integral cross sections of the valence-shell excitations of CFCl(_{3}) have been derived from the excitation thresholds to 5000 eV with the help of BE-scaling method. The present oscillator strengths and cross sections supplement the fundamental database of CFCl(_{3}).

Left panel: a schematic diagram of electron energy loss spectrometer. Right panel: the typical electron-energy-loss-spectra of the valence-shell excitations of CFCl(_3) at an incident electron energy of 1500 eV and the scattering angles of (a) 1.5(circ ) and (b) 4.5(circ ). The valence excitations and Rydberg transitions are marked as vertical bars. (c) A 2-dimensional map of the GOS density of CFCl(_3) vs. the energy-loss and squared momentum transfer.

We discuss relativistic and radiative corrections to the energies of quantum cyclotron states. In particular, it is shown analytically that the leading logarithmic radiative (self-energy) correction to the bound-state energy levels of quantum cyclotron states is state independent and must be interpreted as a magnetic field-dependent correction to the electron’s mass in a Penning trap.

Laser ablation of a metallic thorium foil produces cationic thorium clusters Th(_n^+) composed of up to (n=15) atoms as well as oxide clusters Th(_n)O(_m^+). Mass spectra are recorded using a multi-reflection time-of-flight analyzer. Up to (nlesssim 8), the most abundant species for a given cluster size is the Th(_n)O(_{2n-1}^+) configuration. Notably, pure thorium clusters Th(_n^+) become dominant for (n > rsim 9). Production drops sharply after Th(_{13}^+) indicating increased relative stability associated with a “magic number” cluster size.

We revisit constraints on the value of the electric charge of the neutron and the neutrinos as well as on the electric-charge proton–electron difference (e_p+e_e). We consider phenomenological constraints based on laboratory study of the electrical neutrality of would-be neutral subatomic, atomic, and molecular species under assumption of the conservation of the electric charge in the (beta ) decay that relates the values of (e_p+e_e, e_n, e_nu ). Some of constraints published previously utilized an additional assumption (e_nu =0), which we do not. We dismiss a cosmological constraint at the level of (10^{-35},e) utilized by Particle Data Group (PDG) in their Review of particle properties Workman et al. (Particle Data Group) (Prog Theor Exp Phys 2022:083C01, 2022) as a controversial one which makes the laboratory constraints on (e_nu ) dominant. The phenomenological constraints from the available data of laboratory experiments are obtained as (e_p+e_e=(0.2pm 2.6)times 10^{-21},e), (e_n=(-0.4pm 1.1)times 10^{-21},e), and (e_nu =(0.6pm 3.2)times 10^{-21},e). The ones on (e_p+e_e) and (e_n) are at the same level as the related constraints of PDG but somewhat different because of releasing the value of (e_nu ). Our (e_nu ) constraint is several orders of magnitude weaker than the controversial cosmological result dominated in the PDG constraint, but several orders of magnitude stronger than the other individual (e_nu ) constraints considered by PDG. We also consider consistency of the phenomenological constraints and the Standard Model (SM). The SM ignores the mass term of the neutrinos and cannot describe the neutrino oscillations which makes it not a complete theory but a part of it. We demonstrate that the condition of the cancellation of the triangle anomalies within the complete theory does not disagree with the phenomenological constraints since different extensions of the SM may produce different additional contributions to the anomalies. A choice of the extension fixes the way how those contributions are organized. In particular, we consider a minimal extension of the SM, where leptons ((nu ,e)) are treated the same ways as quarks, which sets (e_p+e_e=0) and allows for numerical strengthening the constraint on (e_n) and (e_nu ), which is (e_n=-e_nu =(-0.4pm 1.0)times 10^{-21},e).

Phenomenological constraint on the value of the electric charge of the neutrino

High-energy proton beams are essential for fundamental research and applied physics. The combined acceleration mechanism based on radiation pressure acceleration has made great progress in obtaining high-energy protons. However, Rayleigh–Taylor instability (RTI) is still a potential influencing factor that will limit the quality of high-energy proton beams. Different from the previous suppression and neglect of RTI, this paper introduces a parabolic density plasma channel to accelerate protons by virtue of the characteristics of RTI. Three-dimensional Particle-in-cell simulations reveal that this scheme achieves high-energy protons with cut-off energy of 39 (textrm{GeV}), total charge of 0.97 (textrm{nC}), and the emittance of 1.12 (mathrm{{mm}};mathrm{{mrad}}) in both the y and z directions. There are locally distributed electrons in the parabolic density plasma channel, and the focusing field around them can effectively focus protons. Compared with the uniform density plasma channel, the parabolic density plasma channel can significantly improve the quality of the proton beam, which could offer significant guidance for the generation and application of high-energy proton beams.