Chiral Effects in Elastic Electron-Molecule Collisions

Electron interaction with methane molecule and accurate determination of its elastic cross-section is a demanding task for both experimental and theoretical standpoints and relevant for our better understanding of the processes in Earth’s and Solar outer planet atmospheres, the greenhouse effect or in plasma physics applications like vapor deposition, complex plasma-wall interactions and edge plasma regions of Tokamak. Methane can serve as a test molecule for advancing novel electron-molecule collision theories. We present a combined experimental and theoretical study of the elastic electron differential cross-section from methane molecule, as well as integral and momentum transfer cross-sections in the intermediate energy range (50–300 eV). The experimental setup, based on a crossed beam technique, comprising of an electron gun, a single capillary gas needle and detection system with a channeltron is used in the measurements. The absolute values for cross-sections are obtained by relative-flow method, using argon as a reference. Theoretical results are acquired using two approximations: simple sum of individual atomic cross-sections and the other with molecular effect taken into the account.

Download Full-text

Calculation of charge form factor of elastic electron scattering based on Skyrme force and relativistic eikonal approximation

International Journal of Modern Physics E ◽

10.1142/s0218301319500150 ◽

2019 ◽

Vol 28 (03) ◽

pp. 1950015

Author(s):

Xiaoyong Guo ◽

Zaijun Wang ◽

Tianjing Li ◽

Jian Liu

Keyword(s):

Electron Scattering ◽

Mean Field ◽

Form Factors ◽

Eikonal Approximation ◽

Skyrme Force ◽

Elastic Electron ◽

Elastic Electron Scattering ◽

Charge Form ◽

Relativistic Treatment ◽

Rmf Model

We construct a scheme to calculate the charge form factors for the elastic electron scattering. Our calculation is based on the relativistic eikonal approximation and the Skyrme–Hartree–Fock equation. To perform our calculation and benchmark the results, eight model nuclei with available experimental data: [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], and [Formula: see text] are considered. For the comparison, the charge form factors calculated by the relativistic mean-field (RMF) model are also provided. Parameter set SLy5 is utilized for the Skyrme force, and the set NL3 is applied for the RMF model. It has been confirmed that combining of a nonrelativistic treatment for the target nucleus with a relativistic treatment for the incident electron may work better to reach highly descriptive and predictive results similar to the pure relativistic treatment. The results of this work are also useful for future experiments to test different inputs of densities for a specific nucleus.

Download Full-text

Zilch vortical effect for fermions

Journal of High Energy Physics ◽

10.1007/jhep05(2021)070 ◽

2021 ◽

Vol 2021 (5) ◽

Author(s):

Artem Alexandrov ◽

Pavel Mitkin

Keyword(s):

Kinetic Theory ◽

Spin Polarization ◽

Wigner Function ◽

Microscopic Theory ◽

Chiral Media ◽

Function Formalism ◽

Chiral Effects ◽

Definition Of ◽

Theory Framework ◽

Full Analogy

Abstract We consider the notion of zilch current that was recently discussed in the literature as an alternative helicity measure for photons. Developing this idea, we suggest the generalization of the zilch for the systems of fermions. We start with the definition of the photonic zilch current in chiral kinetic theory framework and work out field-theoretical definition of the fermionic zilch using the Wigner function formalism. This object has similar properties to the photonic zilch and is conserved in the non-interacting theory. We also show that, in full analogy with a case of photons, the fermionic zilch acquires a non-trivial contribution due to the medium rotation - zilch vortical effect (ZVE) for fermions. Combined with a previously studied ZVE for photons, these results form a wider set of chiral effects parameterized by the spin of the particles and the spin of the current. We briefly discuss the origin of the ZVE, its possible relation to the anomalies in the underlying microscopic theory and possible application for studying the spin polarization in chiral media.

Download Full-text