On Threshold Resummation S-Factor for a System of Two Relativistic Spinor Particles with Arbitrary Masses

2020 ◽  
Vol 23 (4) ◽  
pp. 449-460
Author(s):  
Yu. D. Chernichenko ◽  
L. P. Kaptari ◽  
O. P. Solovtsova
Keyword(s):  
Composite System ◽  
Hamiltonian Formulation ◽  
Quantum Field ◽  
Quasipotential Approach ◽  
Threshold Resummation ◽  
S Factor ◽  
Configuration Representation ◽  
Relativistic Configuration ◽  
The Difference ◽  
Relativistic Configuration Representation

We present a new threshold resummation S-factor obtained for a composite system of two relativistic spin 1/2 particles of arbitrary masses interacting via a Coulomb-like chromodynamical potential. The analysis is performed in the framework of a relativistic quasipotential approach in the Hamiltonian formulation of the quantum field theory in the relativistic configuration representation. The pseudoscalar, vector, and pseudovector systems are considered. The difference in the behavior of the S-factor for these cases is discussed. A connection between the new and the previously obtained S-factors for spinless particles of arbitrary masses and relativistic spinor particles of equal masses is established.

Form Factor of the Two Fermions Bound State: The Case of Equal Masses and Vector Currentl

2021 ◽  
Vol 24 (2) ◽  
pp. 133-144
Author(s):  
Yu. D. Chernichenko
Keyword(s):  
Field Theory ◽  
Form Factor ◽  
Hamiltonian Formulation ◽  
Three Dimensional ◽  
Vector Current ◽  
Bound State ◽  
Quantum Field ◽  
Quasipotential Approach ◽  
New Form ◽  
Relativistic Particles

New form factor components of two relativistic with equal masses fermions bound state in the case of a vector current are obtained. Consideration is performed within the framework of the relativistic quasipotential approach on the basis of covariant Hamiltonian formulation of quantum field theory by transition to three-dimensional relativistic configurational representation in the case of two relativistic particles with equal masses and spin 1/2.

scholarly journals Extended theoretical transition data in C i–iv

2021 ◽  
Vol 502 (3) ◽  
pp. 3780-3799
Author(s):  
W Li ◽  
A M Amarsi ◽  
A Papoulia ◽  
J Ekman ◽  
P Jönsson
Keyword(s):  
Transition Probabilities ◽  
Energy Levels ◽  
Oscillator Strengths ◽  
Atomic Data ◽  
Internal Validation ◽  
Hartree Fock ◽  
Relativistic Configuration ◽  
The Difference ◽  
The One ◽  
Relative Differences

ABSTRACT Accurate atomic data are essential for opacity calculations and for abundance analyses of the Sun and other stars. The aim of this work is to provide accurate and extensive results of energy levels and transition data for C i–iv. The Multiconfiguration Dirac–Hartree–Fock and relativistic configuration interaction methods were used in this work. To improve the quality of the wavefunctions and reduce the relative differences between length and velocity forms for transition data involving high Rydberg states, alternative computational strategies were employed by imposing restrictions on the electron substitutions when constructing the orbital basis for each atom and ion. Transition data, for example, weighted oscillator strengths and transition probabilities, are given for radiative electric dipole (E1) transitions involving levels up to 1s22s22p6s for C i, up to 1s22s27f for C ii, up to 1s22s7f for C iii, and up to 1s28g for C iv. Using the difference between the transition rates in length and velocity gauges as an internal validation, the average uncertainties of all presented E1 transitions are estimated to be 8.05 per cent, 7.20 per cent, 1.77 per cent, and 0.28 per cent, respectively, for C i–iv. Extensive comparisons with available experimental and theoretical results are performed and good agreement is observed for most of the transitions. In addition, the C i data were employed in a re-analysis of the solar carbon abundance. The new transition data give a line-by-line dispersion similar to the one obtained when using transition data that are typically used in stellar spectroscopic applications today.

scholarly journals Hamiltonian Approach to QCD at Finite Temperature

Universe ◽  
2019 ◽  
Vol 5 (2) ◽  
pp. 40
Author(s):  
Hugo Reinhardt ◽  
Davide Campagnari ◽  
Markus Quandt
Keyword(s):  
Field Theory ◽  
Ground State ◽  
Finite Temperature ◽  
Hamiltonian Formulation ◽  
Spatial Dimension ◽  
Quantum Field ◽  
Hamiltonian Approach ◽  
Inverse Temperature ◽  
Chiral Phase ◽  
Novel Approach

A novel approach to the Hamiltonian formulation of quantum field theory at finite temperature is presented. The temperature is introduced by compactification of a spatial dimension. The whole finite-temperature theory is encoded in the ground state on the spatial manifold S 1 ( L ) × R 2 where L is the length of the compactified dimension which defines the inverse temperature. The approach is then applied to the Hamiltonian formulation of QCD in Coulomb gauge to study the chiral phase transition at finite temperatures.

scholarly journals Threshold resummation S factor in QCD: The case of unequal masses

2010 ◽  
Vol 73 (9) ◽  
pp. 1612-1621 ◽  
Author(s):  
O. P. Solovtsova ◽  
Yu. D. Chernichenko
Keyword(s):  
Threshold Resummation ◽  
S Factor

Theoretical Investigation on Effective Thermal Conductivity of a Disk-Shaped Composite System

2010 ◽  
Author(s):  
Yasushi Koito ◽  
Toshio Tomimura ◽  
Shuichi Torii
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Thermal Resistance ◽  
Effective Thermal Conductivity ◽  
Composite System ◽  
Microsoft Excel ◽  
Resistance Network ◽  
Estimation Equations ◽  
The Difference ◽  
Wiring Board

This paper addresses the methodology to estimate the effective thermal conductivity of the wiring board, where the metal wiring network is very complicated and then the thermal conductivity of the metal wiring is more than 1000 times higher than that of the resign board. Based on the concept of analogy between the electric and the thermal resistance network, two types of estimation equations are derived by dividing the composite system parallel or perpendicular to the heated/cooled surface. When the ratio of higher to lower thermal conductivities is less than 10, the estimated values by these equations agree with each other. However, the difference is clearly found between them when the ratio is larger than 100. The estimated values are moreover compared with the exact solutions, which are obtained by numerical simulation of heat transfer using Microsoft Excel, and then the applicability of the present estimation methodology is discussed. It is found that the thermal resistance network obtained by dividing the composite system perpendicular to the heated/cooled surface is effective to estimate the effective thermal conductivity of the composite system.

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