Spin splittings from first-order symmetry-adapted perturbation theory without single-exchange approximation

2019 ◽  
Vol 150 (7) ◽  
pp. 074109 ◽  
Author(s):  
Jonathan M. Waldrop ◽  
Konrad Patkowski
Keyword(s):  
Perturbation Theory ◽  
First Order ◽  
Single Exchange ◽  
Exchange Approximation

scholarly journals Chiral perturbation theory for GR

2020 ◽  
Vol 2020 (9) ◽  
Author(s):  
Kirill Krasnov ◽  
Yuri Shtanov
Keyword(s):  
Perturbation Theory ◽  
Chiral Perturbation ◽  
Perturbative Calculation ◽  
New Formalism ◽  
Yang Mills ◽  
First Order ◽  
Starting Point ◽  
Gauge Fixing ◽  
New Perturbation ◽  
Effective Description

Abstract We describe a new perturbation theory for General Relativity, with the chiral first-order Einstein-Cartan action as the starting point. Our main result is a new gauge-fixing procedure that eliminates the connection-to-connection propagator. All other known first-order formalisms have this propagator non-zero, which significantly increases the combinatorial complexity of any perturbative calculation. In contrast, in the absence of the connection-to-connection propagator, our formalism leads to an effective description in which only the metric (or tetrad) propagates, there are only cubic and quartic vertices, but some vertex legs are special in that they cannot be connected by the propagator. The new formalism is the gravity analog of the well-known and powerful chiral description of Yang-Mills theory.

Note on Interference Effects in Two-Step Reaction Processes

1975 ◽  
Vol 53 (23) ◽  
pp. 2590-2592
Author(s):  
J. Cejpek ◽  
J. Dobeš
Keyword(s):  
Perturbation Theory ◽  
Point Of View ◽  
Order Perturbation ◽  
Interference Effects ◽  
Qualitative Explanation ◽  
First Order ◽  
One Step ◽  
Step Transition ◽  
Reaction Processes ◽  
First Order Perturbation

The reaction processes in which a one-step transition is forbidden are analyzed from the point of view of the first order perturbation theory. The interference between two competing two-step reaction paths is found to be always constructive. A qualitative explanation of the experimentally observed reaction intensities is presented.

scholarly journals Quantum many-body effects on Rydberg excitons in cuprous oxide

2021 ◽  
Author(s):  
D. Semkat ◽  
H. Fehske ◽  
H. Stolz
Keyword(s):  
Perturbation Theory ◽  
Oscillator Strength ◽  
Cuprous Oxide ◽  
Many Body ◽  
Electron Hole ◽  
First Order ◽  
Electron Hole Plasma ◽  
Plasma Line ◽  
Many Body Effects ◽  
First Order Perturbation

AbstractWe investigate quantum many-body effects on Rydberg excitons in cuprous oxide induced by the surrounding electron-hole plasma. Line shifts and widths are calculated by full diagonalisation of the plasma Hamiltonian and compared to results in first order perturbation theory, and the oscillator strength of the exciton lines is analysed.

scholarly journals Mikrowellenspektrum, Struktur, Dipolmoment und internes Hinderungspotential von Dimethyldisulfid

1965 ◽  
Vol 20 (12) ◽  
pp. 1676-1681 ◽  
Author(s):  
D. Sutter ◽  
H. Dreizler ◽  
H. D. Rudolph
Keyword(s):  
Perturbation Theory ◽  
Dipole Moment ◽  
Angular Momentum ◽  
Internal Rotation ◽  
Stark Effect ◽  
Order Perturbation ◽  
Frequency Range ◽  
First Order ◽  
Cross Terms ◽  
Second Order Perturbation Theory

The microwave spectra of CD3 —S —S —CD3 and CH3 —S —S—CH3 have been measured in the frequency range from 5.5 to 34 kmc/sec. From the six rotational constants an r0-structure has been calculated. STARK-effect measurements have been made for the 101 —110 and 202—211 rotational transitions of CH3—S—S—CH3. The dipole moment was calculated to be (1.985±0.01) Debye. An approximate value for the barrier to internal rotation of the two methyl tops is given, V3= (1.6±0.1) kcal. The calculation has been based on triplet splittings of the rotational lines using second order perturbation theory in the torsional wavefunctions and neglecting first order and cross terms in angular momentum.

Feshbach–Villars equation in a κ-Minkowski spacetime

2020 ◽  
Vol 35 (37) ◽  
pp. 2050307
Author(s):  
B. Hamil ◽  
M. Merad
Keyword(s):  
Experimental Data ◽  
Perturbation Theory ◽  
Deformation Parameter ◽  
Order Approximation ◽  
Minkowski Spacetime ◽  
Magnetic Interaction ◽  
Relativistic Limit ◽  
First Order ◽  
Klein Gordon ◽  
First Order Approximation

In this paper, by using the Dirac derivatives the Klein–Gordon (K-G) equation is determined in a [Formula: see text]-Minkowski spacetime. The dispersion relation and the first-order approximation case are deduced. The Feshbach–Villars (FV) equation is derived by applying the new linearization process to the time. We then study the effect of magnetic interaction on energies spectrum in a [Formula: see text]-Minkowski spacetime as an application, as a result we found that the energies spectrum are not symmetrical. We also study the case of hydrogen atom in non-relativistic limit by using perturbation theory. The upper bound of the [Formula: see text]-deformation parameter is evaluate, on the basis of the experimental data for [Formula: see text] transition frequency.

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