Migdal Theory Research Articles

Local Strongman and Political Dynasty: Political Economic Analysis of Aang Hamid Suganda in Kuningan Regency, 2003-2018

Political dynasty is the inheritance of political power among members of a family over several generations. This study analyzes how political dynasties were built by local strongmen in Kuningan Regency. Kuningan was chosen as the locus of this study on the grounds that in that region a political dynasty was built without experiencing 'resistance' from the residents, and it still continues today. This study uses a qualitative method with a case study approach and is complemented by the use of Joel S. Migdal's theory about local strongman and local bossism from John T. Sidel. The findings were that Aang Hamid Suganda (AHAS) was a local strongman from among successful entrepreneurs and a cadre of PDIP, the political party that won the election in Kuningan. Support for AHAS soared PDIP's rating in Kuningan, symbiotically with his success as Regent for two consecutive terms. The AHAS political dynasty shows that the successful inheritance of power within a family can be done through the effectiveness of political strategy, the significance of regional development, and the strong social influence created.

Superconducting Energy Gap in Hole-Doped Graphene Beyond the Migdal's Theory

In this work we analyze impact of non-adiabatic effects on the superconducting energy gap in the hole-doped graphene. By using the Eliashberg formalism beyond the Migdal's theorem, we present that the non-adiabatic effects strongly influence the superconducting energy gap in the exemplary boron-doped graphene. In particular, the non-adiabatic effects, as represented by the first order vertex corrections to the electron-phonon interaction, supplement Coulomb depairing correlations and suppress the superconducting state. In summary, the obtained results confirm previous studies on superconductivity in two-dimensional materials and show that the corresponding superconducting phase may be notably affected by the non-adiabatic effects.

Application of an Improved Molière Theory to the Description of the Landau–Pomeranchuk–Migdal Effect

We present exact analytical and numerical results for high-energy Coulomb corrections (CCs) to the parameters of an improved Molière multiple scattering theory over a wide range of the nuclear charge number Z of the target atom and show that the values of these corrections increase up to 40% − 45% for Z = 92. We also report our results of applying this improved Molière multiple scattering theory for calculating CCs to the quantities of the classical Migdal theory of the Landau–Pomeranchuk–Migdal (LPM) effect, and we demonstrate that the improved Migdal LPM effect theory allow one to completely eliminate the discrepancy between the predictions of the LPM effect theory and their measurement at least for high-Z targets. We also obtained analytical and numerical results concerning high-energy CCs to the quantities of the quantum Migdal theory of the LPM effect in the ranges of Z from 6 to 92 and the Molière expansion parameter B from 4.5 to 8.5, and we managed to show that the magnitude of relative CC to the spectral radiation rate reaches −19% in these ranges considered and must be borne in mind, e.g., in the Monte-Carlo analysis of electromagnetic cascade LPM showers in extremely high-energy region.

CONTESTATION BETWEEN STATE AND NONSTATE ACTORS IN ZAKAH MANAGEMENT IN INDONESIA

This paper is aimed to study the contestation between state and civil society in zakah management in Indonesia as a part of socio political dynamic of secularization of zakah as an Islamic economy instrument in Indonesian situation. More specifically, about how the state of Indonesia manages to secularize the zakah as a divine instrument into a country which adopt semi-secular system. The research scrutinizes the contestation between state and civil society in zakah management through the cases and trial observation at Indonesian Constitutional Court (on judicial review the Law No. 23/2011 on Zakat Management) and Supreme Court (judicial review Government Regulation No. 14/2014 on Zakat Management). Some resistances to local ordinances on zakah management in various places in Indonesia are also being studied. The research has shown that the practice of zakah in Indonesia is specific and different from the practices in other Muslim countries. In a predominantly Muslim country, zakah practices in Indonesia are actually a product of Indonesian Muslims’ social, cultural, and political dynamics. The research employs Joel S. Migdal theory on contestation. In these Migdalian’s “junctures” between state forces and social forces, these non-state zakah agencies naturally launch contestation in both forms of struggle and accommodation. These non-state agencies accommodate their survival through modernization of their daily operation to reach more sources of funds and targets as well as launch a legal struggle to annul some disadvantageous parts within the newly arrived secularization of zakah management through the politicization of zakah. In the meeting grounds for state and social forces, the results vacillate - depending on the place and context of the contestation - between what Migdal (1994) calls the state’s appropriation of social forces or symbols and the dominant social forces’ adaptation to the presence of a state’s components. In this set of mutual accommodation strategies, all become possible: co-optation, creation of multiple networks of clients, and corruption.

Application of a Revised Moliere Theory to the Description of the Landau-Pomeranchuk Effect

Using the Coulomb corrections to some important parameters of a revised Moliere multiple scattering theory, we have obtained analytically and numerically the Coulomb corrections to the quantities of the Migdal theory of the Landau-Pomeranchuk (LPM) effect for sufficiently thick targets. We showed that the Coulomb correction to the spectral bremsstrahlung rate of this theory allows completely eliminating the discrepancy between the theory and experiment at leastfor high Z experimental targets.

On the effect of the [formula omitted] in hypernuclear non-mesonic weak decay: A microscopic approach

The non-mesonic weak decay of Λ-hypernuclei is studied within a microscopic diagrammatic approach which includes, for the first time, the effect or the Δ-baryon resonance. We adopt a nuclear matter formalism extended to finite nuclei via the local density approximation, a one-meson exchange weak transition potential, a Bonn nucleon–nucleon strong potential and a ΔN→NN strong potential based on the Landau–Migdal theory. Ground state correlations and final state interactions (FSI), at second order in the baryon–baryon strong interaction, are introduced on the same footing for all the isospin channels of one- and two-nucleon induced decays. Weak decay rates and single and double-coincidence nucleon spectra are predicted for CΛ12 and compared with recent KEK and FINUDA data. The Δ(1232) introduces new FSI-induced decay mechanisms which lead to an improvement when comparing the obtained nucleon spectra with data, while it turns out to have a negligible effect on the decay rates. Discrepancies with experiment remain only for emission spectra involving protons, but are mostly restricted to double-nucleon correlations in the non-back-to-back kinematics.

A general semi-analytic method to simulate discrete bremsstrahlung at very low radiated photon energies by the Monte Carlo method

A computer code for Monte-Carlo simulations in the framework of the GEANT 3 toolkit has been implemented for the description of the discrete bremsstrahlung radiation from high energy electrons crossing thick (semi-infinite) targets. The code is based on the Migdal theory which includes the LPM and dielectric suppression. Validation of the code has been performed by a comparison with the data from the SLAC E-146 experiment. The agreement between simulations and experimental data is generally very good.

Implementation of the LPM effect in the discrete-bremsstrahlung simulation of GEANT 3 and GEANT 4

Experimental data, recently measured at CERN, on the LPM effect have been used to benchmark the description of the discrete bremsstrahlung incorporated into the GEANT 3 and GEANT 4 codes. The limited accuracy of the native versions required a major revision in the framework of the original Migdal theory. The results obtained with the new implementation agree quite satisfactorily with measurements. The stability of the calculations when several parameters are varied has been thoroughly investigated.

Short range correlations and spectral functions in asymmetric nuclear matter

Dynamical correlations in asymmetric infinite nuclear matter are investigated in a transport theoretical approach. Self-energies due to short range correlations and their influence on the nucleon spectral functions are described in an approach accounting for a realistic treatment of mean-field dynamics and a self-consistently derived quasiparticle interaction. Landau–Migdal theory is used to derived the short range interaction from a phenomenological Skyrme energy density functional. The spectral functions in asymmetric nuclear matter are found to follow in their gross features closely the patterns observed previously in symmetric nuclear matter. An interesting sensitivity of dynamical self-energies and spectral functions on the momentum structure of the underlying interactions is found.

Gauge invariance and the κ–gl relation

The connection between the enhancement factor of the photonuclear E1 sum rule and the orbital angular momentum g-factor of a bound nucleon is discussed in the framework of the Landau–Migdal theory for isospin asymmetric nuclear matter, and compared to empirical informations.

The relation between the photonuclear E1 sum rule and the effective orbital g-factor

The connection between the enhancement factor (1+ κ) of the photonuclear E1 sum rule and the orbital angular momentum g-factor ( g ℓ) of a bound nucleon is investigated in the framework of the Landau–Migdal theory for isospin asymmetric nuclear matter. Special emphasis is put on the role of gauge invariance to establish the κ– g ℓ relation. By identifying the physical processes which are taken into account in κ and g ℓ, the validity and limitations of this relation will be discussed. The connections to the collective excitations and to nuclear Compton scattering are also shown.

Landau-Pomeranchuk-Migdal effect for multihundred GeV electrons

Experimental results for the bremsstrahlung energy loss of 149, 207, and 287 GeV electrons in thin Ir, Ta, and Cu targets are presented. For each target and energy, a comparison between simulated values based on the Landau-Pomeranchuk-Migdal (LPM) suppression of incoherent bremsstrahlung is shown. For the electron energies investigated, the LPM effect enters the quantum regime where the recoil imposed on the electron by the emitted photon becomes important. Good agreement between simulations based on Migdal's theory and data from the experiment is found, indicating that the LPM suppression is well understood also in the quantum regime. Results from a comparison between simulations with the ``threshold'' energy ${E}_{\mathrm{LPM}}$ as a free parameter and the data are shown. This analysis reproduces the expected trend as a function of nominal radiation length, but yields values that tend to be low compared to Migdal's theory.

Polaronic behavior in single- and many-electron Holstein model: A new perturbation approach

A new perturbation approach is developed for single- and many-electron Holstein model in one-, two-, and three-dimension. The results show that this approach has a good agreement with the Migdal theory in the adiabatic regime when the coupling is moderate (λ < 1), but with the Lang-Firsov theory in the antiadiabatic regime ( ω/W≫ 1). In the intermediate region, our approach can describe the transition from a large-polaron Fermi-liquid to the small-polaron, and this transition may be discontinuous in adiabatic regime, which means a phase transition appears in many-electron system. In single-electron case, we eliminate the abrupt transition using the degenerate perturbation theory, and the calculated ground state energy and effective mass are successfully compared with those of previous authors. Besides, the method has the advantage of requiring little computational effort.

Influence of the LPM effect and dielectric suppression on particle air showers

An analysis of the influence of the Landau-Migdal-Pomeranchuk (LPM) effect on the development of air showers initiated by astroparticles is presented. The theory of Migdal is studied and compared with other theoretical methods, particularly the Blankenbecler-Drell approach. By means of realistic computer simulations and using algorithms that emulate Migdal's theory, including also the so-called dielectric suppression, we study the behavior of the relevant observables in the case of ultrahigh energy primaries. We find that the LPM effect can significantly modify the development of high energy electromagnetic showers in certain cases.

Feynman path integral method and Landau-Pomeranchuk-Migdal effect for finite targets

A Feynman path integral formalism for treating the suppression of bremsstrahlung radiation of long-wavelength photons, the Landau-Pomeranchuk-Migdal (LPM) effect, in a target of finite thickness with multiple scattering is developed. Taking into account the side effect yields corrections to the Migdal theory. The method is also applied to the treatment of the standard LPM effect in the presence of an external field.

Many-particle effects in nucleus-nucleus collisions

Migdal's theory of finite Fermi systems is applied for the description of nucleus-nucleus collisions at laboratory energies less than a few GeV A . It is taken into account that the pionic degree of freedom softens in nuclear matter. Free paths of nucléon and pion quasiparticles are calculated. Compact formulas are written for pion, nucleon- and photon-production cross sections. In addenda, the main formulas are presented for the NN-interaction amplitude and pion polarization operator in non-equilibrium and heated equilibrium nuclear matter.

Moments and electromagnetic transitions for even-odd nuclei in the Pb region

Migdal's theory of finite Fermi systems has been applied to the calculation of electromagnetic moments and transitions for neighbouring even-odd nuclei of 208Pb. The p-h vertex is deduced from a bare nucleon-nucleon potential in a nuclear matter calculation and transposed to finite nuclei by means of a local density approximation. Comparison with experimental data shows almost the same fair agreement as the semiphenomenological treatment. For the configuration space two main shells above and below the Fermi surface were used.

Meson exchange and the theory of finite fermi systems

The spin-dependent parameters g 0 and g' 0 in Migdal's theory of finite Fermi systems are studied. Assuming their values to be such as to reproduce the M1 states in 208Pb at 7 and 8 MeV, the origin of these (large) values in meson-exchange contributions to the nucleon-nucleon force is studied. Pion exchange contributes little, because of cancellation between matrix elements from the spin-spin and tensor components. The largest, nearly equal, contributions to g 0 and g' 0 come from p-meson exchange. In order to explain the large values needed for g 0 and g' 0, the tensor coupling of the ρ-meson must be substantially larger than the effective ones found in current phenomenological potentials, such as the Reid soft-core and Hamada-Johnston ones. The large value of the coupling needed follows from work analyzing nucleon form factors.

L- andM-shell electron shake-off accompanying alpha decay

The ${L}_{\mathrm{I}}$-, ${L}_{\mathrm{II}}$-, ${L}_{\mathrm{III}}$-, and $M$-shell vacancy distributions accompanying electron shake-off in the $\ensuremath{\alpha}$ decay of $^{210}\mathrm{Po}$ have been measured by $\ensuremath{\alpha}$-x-ray two parameter coincidence techniques. The ionization probabilities and the errors due to our measurements were (5.11\ifmmode\pm\else\textpm\fi{}0.40, 0.62\ifmmode\pm\else\textpm\fi{}0.06, and 1.50\ifmmode\pm\else\textpm\fi{}0.19) \ifmmode\times\else\texttimes\fi{} ${10}^{\ensuremath{-}4}$ for the ${L}_{\mathrm{I}}$, ${L}_{\mathrm{II}}$, and ${L}_{\mathrm{III}}$ subshells, respectively, and (1.8\ifmmode\pm\else\textpm\fi{}0.4) \ifmmode\times\else\texttimes\fi{} ${10}^{\ensuremath{-}2}$ for the $M$ shell. Possible errors in tabulated fluorescence and Coster-Kronig yields could increase the uncertainties to (1.7, 0.5, 0.8) \ifmmode\times\else\texttimes\fi{} ${10}^{\ensuremath{-}4}$ and 0.6 \ifmmode\times\else\texttimes\fi{} ${10}^{\ensuremath{-}2}$, respectively. The energies and peak shapes of the $\ensuremath{\alpha}$ groups in coincidence with $L\ensuremath{\alpha}$, $L\ensuremath{\beta}$, $L\ensuremath{\gamma}$, and $M$ x rays were also measured. The coincident groups were, respectively, 12.6\ifmmode\pm\else\textpm\fi{}1.4, 13.8\ifmmode\pm\else\textpm\fi{}1.4, 17.6\ifmmode\pm\else\textpm\fi{}2.1, and 3.1\ifmmode\pm\else\textpm\fi{}1.0 keV lower in energy than the $^{210}\mathrm{Po}$ ${\ensuremath{\alpha}}_{0}$ peak. Theoretical calculations by Hansen are in closer agreement with the experimental values for the $L$ subshells than Migdal's theory, but discrepancies of about a factor of 2 still exist.RADIOACTIVITY $^{210}\mathrm{Po}$; measured $\ensuremath{\alpha}\ensuremath{-}L$ and $\ensuremath{\alpha}\ensuremath{-}M$ x-ray coin. Deduced ${L}_{\mathrm{I}}$, ${L}_{\mathrm{II}}$, ${L}_{\mathrm{III}}$, $M$ electron shake-off abundances, energy distribution.

An open-shell finite Fermi systems approach to the structure of A = 12 nuclei

An extension of Migdal's theory of finite Fermi systems is specialized to an open-shell calculation of the T = 1 states in 12C. The over-all fit of the low energy excitation spectrum is found to be satisfactory. The rates of the weak transitions 12 B gs →μ− →β− 12 C gs are accurately predicted, yielding a considerable improvement over the closed-shell RPA calculation. Overestimation of the isovector magnetic dipole sum rule strength is observed and discussed.