The spin and flavor symmetries of the heavy quark effective theory are employed to discuss the exclusive cross sections for pair production of heavy mesons in photon-photon collision. The ratios of the exclusive cross sections for heavy mesons are obtained explicitly and the validity of results is discussed.

As Maria Krawczyk remarked in her introductory talk on structure functions [1] , the virtual photon structure provides a unique test of QCD. In this talk I would like to discuss the polarized and unpolarized virtual photon structures. But because of the limitation of the allocated time, I will mainly focus my talk on the polarized virtual photon structure. Recently there has been growing intere...


 Today, the speed of light is one cornerstones modern physics. It maximum limit for transferring information, and plays a very central role in relativity theory. also seems to be same as assumed measured gravity (gravitons and/or gravitational waves). We are not questioning light, we indeed think it that identical ofgravity, but photons lead us second limit, which will term Planck speed. ...

We computed twist-4 part of the photon spin-flip amplitude in deeply virtual Compton scattering on a nucleon in the Wandzura-Wilczek approximation. We found a factorizable contribution, which arises from photon scattering on quarks with non-zero angular momentum along the collision axis. As the genuine twist-2 amplitude arises at the NLO, for moderate virtualities of the hard photon, Q2 ≤ 10 Ge...

Delbrück scattering is an elastic scattering of a photon in the Coulomb field of a nucleus via a virtual electron loop. The contribution of this virtual subprocess to the emission of a photon in the collision of ultra-relativistic nuclei Z1 Z2 → Z1 Z2 γ is considered. We identify the incoming virtual photon as being generated by one of the relativistic nuclei involved in the binary collision an...

We analyze the one-photon mechanism of $e^+e^-$ pair production in collision nonrelativistic nuclei. The contribution electric quadrupole radiation virtual photon to corresponding cross section is found. effect finite nuclear size considered detail. A comparison made with dipole and two-photon mechanism. It shown that dominant a wide range relative velocities. for capture an electron by one nuc...

The earlier history of two–photon physics is reviewed. The term two–photon processes is used now for the reactions in which some system of particles is produced in collision of two photons, either real or virtual. In the study of these processes the principal goal is to describe main features of proper two–photon process separating it from mechanism which responsible for the production of incid...

By utilizing the order rearrangement of the single photon sequence and unitary transformations, a multiparty controlled quantum communication scheme for Carrier Sense Multiple Access with Collision Detection (CSMA/CD) is presented. In this scheme, messages can only be recovered by the receivers with the permission of all controllers. It is shown that the security of messages transmission can be...

We demonstrate a novel method of observing single particle collision events with electrogenerated chemiluminescence (ECL). A single event is characterized by the enhancement of ECL intensity during the collision of an individual platinum nanoparticle (Pt NP) on an indium tin oxide electrode, which catalyzes the oxidation of Ru(bpy)3(2+) and a coreactant, for example, tri- n-propylamine (TPrA), ...

Top quark threshold production in γγ collision in the next-to-leading order. Abstract The total cross section of the top quark-antiquark pair production near threshold in γγ collision is computed analytically up to the next-to-leading order in perturbative and nonrelativistic expansion for general photon helicity. The approximation includes the first order corrections in the strong coupling con...