Should U(1) long-range forces be associated to electron, muon and/or tau quantum number then their ”fine structure constants” are seen to be bound by nucleosynthesis data to be less than about 1.7× 10. For τ and μ this is the best upper limit up to date. ∗Laboratoire associé au C.N.R.S. — URA D0063. While the rôle of electric charge, weak isospin, and color is completely clarified in the modern...

The H> and V> outputs of a Polarizing Beam Splitter can be combined to restore the original input superposition state, as long as no knowledge is obtained regarding the path taken through the PBS. Using this principle, it should be possible to create entangled photons from the identical H> and V> components of different polarization entangled photons. These “Frankenstein” photons will also be p...

The parton model is very useful to study scattering processes at very high energies. For example, nuclei consist of nucleons, which in turn consist of quarks and gluons, photons consist of lepton pairs, electrons of photons, etc.. Relativistic nuclei have photons as an important constituent at low enough virtuality Q = −q of the photon, due to the coherent action of all charges in the nucleus. ...

Entangling independent photons is not only of fundamental interest but also of crucial importance for quantum-information science. Two-photon interference is a major method for entangling independent identical photons. If two photons are different in color, perfect two-photon coalescence can no longer happen, which makes the entangling of different-color photons difficult to realize. In this Le...

Regenerated high energy emissions from gamma-ray bursts (GRBs) are studied in detail. If the primary emission spectrum extends to TeV range, these very high energy photons will be absorbed by the cosmic infrared background (CIB). The created high energy electron-positron pairs up-scatter not only cosmic microwave background (CMB) photons but also CIB photons, and secondary photons are generated...

Centrifugal pressure of matter spiralling onto black holes, have long been known to produce standing or oscillating shocks. The post-shock disc puffs up in the form of a torus, which intercepts soft photons from the outer Keplerian disc and inverse Comptonizes them to produce hard photons. The post-shock region also produces jets. We study the interaction of both hard photons and soft photons, ...

Introduction: The heavyweight concretes have been widely used for constructing medical or industrial radiation facilities with photon sources. Materials and Methods: In this study, heavy concretes containing galena (PbS) and several borated minerals are proposed as suitable materials against photons. The shielding properties of 21 galena concretes containing seven borated minerals with three m...

Background: High density concrete is extensively used for efficient radiation attenuation in radiotherapy rooms and nuclear reactors. Over the past eight years, some efficient galena-based concrete samples for shielding X or gamma rays was produced. The goal of this study was to produce a novel high density concrete against neutron and photon radiations using tourmaline and galena. Materials an...