نتایج جستجو برای: photons

تعداد نتایج: 47312  

Journal: :Fortschritte der Physik 2021

The mixing of graviphotons and dark brane photons to the Standard Model hypercharge is analyzed in full generality, weakly-coupled string theory. Both direct as well effective terms that provide after inclusion SM corrections are estimated lowest order. results compared with Effective Field Theory (EFT) couplings, originating a hidden large-N theory coupled where composite. typically subleading...

Journal: :Physical review. D, Particles and fields 1996
Summers

We present a simple method of removing the singularities associated with soft photon emission to all orders in perturbation theory through exponentiation, while keeping a consistent description of hard photon emission. We apply this method to the process e + e ? ! + ? + n where we include both Z 0 and exchange and retain the muon mass dependence. The photonic radiation is allowed to be radiated...

2009
Alessandro Mirizzi Javier Redondo Günter Sigl

Various extensions of the Standard Model predict the existence of hidden photons kinetically mixing with the ordinary photon. This mixing leads to oscillations between photons and hidden photons, analogous to the observed oscillations between different neutrino flavors. In this context, we derive new bounds on the photon-hidden photon mixing parameters using the high precision cosmic microwave ...

Journal: :iranian journal of nuclear medicine 2004
nasrollah jabbari hossein rajabi hassan firoozabadi fereidoon rastgoo nahid yaghoobi

introduction: scatter radiation is one of the major sources of error in nuclear medicine data processing. different methods of scatter correction have been introduced in order to improve the quality of data. however the best method is to avoid recording of scatter photons in acquisition. the only difference between scattered and non-scattered photons is the energy. pulse height analyzer is the ...

Abstract: The intensity of Compton scattered γ-ray photons provide useful information about the electron density distribution of a test sample. Because of photon attenuation, the application of this method is limited to a certain depth of the sample (saturation depth). The saturation depth value depends on the energy and intensity of primary photons and on the material of the sample. In this...

Background: This study aims to investigate radiation beam geometry of Cyberknife beam and change in dosimetric characteristics of six megavoltage (6MV) flattening filter free (FFF) beam after passing through high density cadmium free compensator alloy.Material and Methods: In this experimental study, changes in FFF beam dosimetric characteristics after passing through compensator alloy wa...

2009
F. W. Sun

The indistinguishability of independent single photons is presented by decomposing the single photon pulse into the mixed state of different transform-limited pulses. The entanglement between single photons and outer environment or other photons induces the distribution of the center frequencies of those transform-limited pulses and makes photons distinguishable. Only the single photons with th...

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