There is some experimental evidence that some stars are older than the Universe in General Relativity based cosmology. In TGD based cosmology the paradox has explanation. Photons can be either topologically condensed on background spacetime surface or in ’vapour phase’ that is progate in M + × CP2 as small surfaces. The time for propagation from A to B is in general larger in condensate than in...

We experimentally demonstrate the first quantum system entangled in every degree of freedom (hyper-entangled). Using pairs of photons produced in spontaneous parametric downconversion, we verify entanglement by observing a Bell-type inequality violation in each degree of freedom: polarization, spatial mode and time-energy. We also produce and characterize maximally hyperentangled states and nov...

We present a short review of the concept of photon wave function and the photon wave equation which represents the Schrödinger equation for the photon. Photon wave function puts the photon on the same footing as particles with mass and presents the first quantization formulation for electromagnetic fields. Because the photon has zero rest mass and it always moves with speed of light, the quantu...

The decays of the η meson are reviewed in the framework of Chiral Perturbation Theory. Particular attention is devoted to the electromagnetic channels involving photons, either in the final or intermediate states.

One of the most direct probes of the QGP is the radiation of thermal photons, emerging directly from the thermalized system and providing, in principle, the temperature in its hottest phases [1]. However, photons are largely produced in hadronic decays, as well as in QCD processes, such as annihilation and Compton, that occur before thermalization. Thermally produced photons must be distinguish...

This contribution describes two recent measurements of isolated photons appearing in photoproduction (measured by ZEUS) and deep inelastic scattering (measured by H1) at the ep collider HERA. 1. Introduction Isolated photons with high transverse momentum in the final state are a sensitive probe of the dynamics of the hard sub-process, since they are largely insensitive to hadronisation and frag...

The process of electron-positron pair production by linearly polarized photons is used as a polarimeter to perform mobile measurement of linear photon polarization. In the limit of high photon energies, ω, the distributions of the recoil-electron momentum and azimuthal angle do not depend on the photon energy in the laboratory frame. We calculate the power corrections of order m/ω to the above ...

The description of longitudinal photons is far from trivial, and their phenomenological importance is largely unknown. While the cross section for direct interactions is calculable, an even more important contribution could come from resolved states. In the development of our model for the interactions of (real and) virtual photons, we have modeled resolved longitudinal effects by simple multip...

After a brief review of the production dynamics of prompt single photons in hadron collisions, I summarize a new QCD calculation of the transverse momentum distribution of continuum prompt photon pairs produced by QCD subprocesses, including all-orders soft-gluon resummation valid at next-to-next-to-leading logarithmic accuracy. Resummation is necessary to obtain reliable predictions, as well a...