scholarly journals Classical sub-subleading soft photon and soft graviton theorems in four spacetime dimensions

2020 ◽  
Vol 2020 (12) ◽  
Author(s):  
Biswajit Sahoo
Keyword(s):  
Fourier Transformation ◽  
Soft Photon ◽  
Scattering Process ◽  
Retarded Time ◽  
Long Wavelength ◽  
Macroscopic Objects ◽  
Loop Amplitudes

Abstract Classical soft photon and soft graviton theorems determine long wavelength electromagnetic and gravitational waveforms for a general classical scattering process in terms of the electric charges and asymptotic momenta of the ingoing and outgoing macroscopic objects. Performing Fourier transformation of the electromagnetic and gravitational waveforms in the frequency variable one finds electromagnetic and gravitational waveforms at late and early retarded time. Here extending the formalism developed in [1], we derive sub-subleading electromagnetic and gravitational waveforms which behave like u−2(ln u) at early and late retarded time u in four spacetime dimensions. We also have derived the sub-subleading soft photon theorem analyzing two loop amplitudes in scalar QED. Finally, we conjectured the structure of leading non-analytic contribution to (sub)n-leading classical soft photon and graviton theorems which behave like u−n(ln u)n−1 for early and late retarded time u.

scholarly journals Ward identity for loop level soft photon theorem for massless QED coupled to gravity

2020 ◽  
Vol 2020 (10) ◽  
Author(s):  
Sayali Atul Bhatkar
Keyword(s):  
Long Range ◽  
Conservation Law ◽  
Ward Identity ◽  
Gravitational Force ◽  
Soft Photon ◽  
Loop Level ◽  
New Feature ◽  
Loop Amplitudes

Abstract Motivated by Campiglia and Laddha [1], we show that the Sahoo-Sen soft photon theorem [2] for loop amplitudes is equivalent to an asymptotic conservation law. This asymptotic charge is directly related to the dressing of fields due to long range forces exclusively present in four spacetime dimensions. In presence of gravity, the new feature is that photons also acquire a dressing due to long range gravitational force and this dressing contributes to the asymptotic charge.

Activated Prominences; Mechanisms for Activation and Eruption

1979 ◽  
Vol 44 ◽  
pp. 307-313
Author(s):  
D.S. Spicer
Keyword(s):  
Pressure Gradient ◽  
Density Gradient ◽  
Current Density ◽  
Convective Instability ◽  
Tearing Mode ◽  
Magnetic Shear ◽  
Long Wavelength ◽  
Ideal Mhd ◽  
Gradient Change ◽  
Accelerated Particles

A possible relationship between the hot prominence transition sheath, increased internal turbulent and/or helical motion prior to prominence eruption and the prominence eruption (“disparition brusque”) is discussed. The associated darkening of the filament or brightening of the prominence is interpreted as a change in the prominence’s internal pressure gradient which, if of the correct sign, can lead to short wavelength turbulent convection within the prominence. Associated with such a pressure gradient change may be the alteration of the current density gradient within the prominence. Such a change in the current density gradient may also be due to the relative motion of the neighbouring plages thereby increasing the magnetic shear within the prominence, i.e., steepening the current density gradient. Depending on the magnitude of the current density gradient, i.e., magnetic shear, disruption of the prominence can occur by either a long wavelength ideal MHD helical (“kink”) convective instability and/or a long wavelength resistive helical (“kink”) convective instability (tearing mode). The long wavelength ideal MHD helical instability will lead to helical rotation and thus unwinding due to diamagnetic effects and plasma ejections due to convection. The long wavelength resistive helical instability will lead to both unwinding and plasma ejections, but also to accelerated plasma flow, long wavelength magnetic field filamentation, accelerated particles and long wavelength heating internal to the prominence.

Simulations of high-resolution images of amorphous silicon films

1986 ◽  
Vol 44 ◽  
pp. 544-545
Author(s):  
G. Y. Fan ◽  
J. M. Cowley
Keyword(s):  
Electron Microscope ◽  
High Frequency ◽  
Fourier Transformation ◽  
Amorphous Materials ◽  
Low Frequency ◽  
Chromatic Aberration ◽  
Structure Information ◽  
Frequency Components ◽  
High Resolution Images ◽  
Spatial Frequency Spectrum

It is well known that the structure information on the specimen is not always faithfully transferred through the electron microscope. Firstly, the spatial frequency spectrum is modulated by the transfer function (TF) at the focal plane. Secondly, the spectrum suffers high frequency cut-off by the aperture (or effectively damping terms such as chromatic aberration). While these do not have essential effect on imaging crystal periodicity as long as the low order Bragg spots are inside the aperture, although the contrast may be reversed, they may change the appearance of images of amorphous materials completely. Because the spectrum of amorphous materials is continuous, modulation of it emphasizes some components while weakening others. Especially the cut-off of high frequency components, which contribute to amorphous image just as strongly as low frequency components can have a fundamental effect. This can be illustrated through computer simulation. Imaging of a whitenoise object with an electron microscope without TF limitation gives Fig. 1a, which is obtained by Fourier transformation of a constant amplitude combined with random phases generated by computer.

Quantum fluctuations have been shown to affect macroscopic objects

Nature ◽  
2020 ◽  
Vol 583 (7814) ◽  
pp. 31-32
Author(s):  
Valeria Sequino ◽  
Mateusz Bawaj
Keyword(s):  
Quantum Fluctuations ◽  
Macroscopic Objects

Dectection of early thrombus formation in LVAD by accoustic fast fourier transformation (FFT) analysis. A novel approach for monitoring

2014 ◽  
Vol 62 (S 01) ◽  
Author(s):  
P. von Samson-Himmelstjerna ◽  
A. Meyer ◽  
T. Müller ◽  
N. Zießnitz ◽  
J. Garbade ◽  
...  
Keyword(s):  
Fourier Transformation ◽  
Thrombus Formation ◽  
Fast Fourier Transformation ◽  
Novel Approach ◽  
Fft Analysis

Zur Anwendung der harmonischen Analyse bei der Funktionsszintigraphie des Herzens

1979 ◽  
Vol 18 (04) ◽  
pp. 167-171 ◽  
Author(s):  
R. Knopp ◽  
H.-P. Breuel ◽  
P. Fischer
Keyword(s):  
Fourier Transformation

ZusammenfassungDie nach Gleichverteilung von 99mTc-Serumalbumin szintigraphisch gewonnenen Volumenkurven des linken Ventrikels werden zur Gewinnung aussagefähiger Ergebnisse einer harmonischen Analyse unterzogen. Es ergibt sich hierdurch die Möglichkeit der quantitativen Analyse der Volumenkurve in geschlossener Form. Die Resynthese nach Fourier-Transformation stellt für den vorliegenden Funktionstyp ein gut geeignetes Glättungsverfahren dar, so daß die aus den Volumenkurven berechneten Parameter Ejektionsfraktion, maximale Austreibungs- und Füllungsgeschwindigkeit mit großer Genauigkeit erfaßt werden.

Eliminierung von Organbewegungen in Szintigrammen mit Hilfe eines Filterverfahrens

1973 ◽  
Vol 12 (04) ◽  
pp. 1-11
Author(s):  
P. Schmidlin
Keyword(s):  
Fourier Transformation ◽  
Wird Eine

ZusammenfassungEs wird eine Methode beschrieben, mit deren Hilfe Szintigramme auf Fehler korrigiert werden können, die durch Bewegung oder Atmen des Patienten entstanden sind. Die Methode benutzt keine mechanischen oder elektronischen Zusätze. Die Korrektur umfaßt eine Fourier-Transformation der Originalmessung im Zeitbereich, ein Herausfiltern der Atemfrequenz und eine Rücktransformation. Möglichkeiten und Grenzen der Methode werden diskutiert und ein Beispiel gezeigt.

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