In constrast to discretized space-time approximations to continuum quantum field theories, discretized velocity space approximations to continuum quantum field theories are investigated. A fourmomentum operator is given in terms of bare fermion-antifermionboson creation and annihilation operators with discrete indices. In continuum quantum field theories the fermion-antifermion creation and ann...

On the basis of phenomenological model of the orthopositronium annihilation ‘isotope anomaly’ in gaseous neon (lifetime spectra, positrons source Na) the realistic estimation of an additinal mode (∼ 0.2%) of the orthopositronium annihilation is received. PACS: 36.10.Dr, 13.90.+i, 06.09.+v In huge volume of the data on lifetime spectra of annihilation in substance of positrons from β-decay Na Na...

In light harvesting complex II (LHCII) of higher plants and green algae, carotenoids (Cars) have an important function to quench chlorophyll (Chl) triplet states and therefore avoid the production of harmful singlet oxygen. The resulting Car triplet states lead to a non-linear self-quenching mechanism called singlet-triplet (S-T) annihilation that strongly depends on the excitation density. In ...

We discuss the possibility to observe the products of dark matter annihilation that was going on in the early Universe. Of all the particles that could be generated by this process we consider only photons, as they are both uncharged and easily detectable. The earlier the Universe was, the higher the dark matter concentration n and the annihilation rate (proportional to n) were. However, the em...

The outcomes of annihilation are known, including some of the intermediary products, and the process can be represented by Feynman diagrams and modelled mathematically. However the mechanisms of annihilation at a deeper fundamental level are unknown. How exactly does matter and antimatter convert into photons? How does mass change into energy? This paper develops an answer by providing a theory...

Large positron annihilation cross sections have been observed for a variety of molecules at various energies below the threshold for positronium formation. These large values are due to vibrational Feshbach resonances VFRs , in which the positron attaches to the molecule while exciting a vibration. This leads to rates of annihilation far greater than those expected for a simple collision. The d...

Kinetic equations are analyzed for thermal degradation of polymers. The governing relations are based on the fragmentation–annihilation concept. Explicit solutions to these equations are derived in two particular cases of interest. For arbitrary values of adjustable parameters, the evolution of the number-average and mass-average molecular weights of polymers is analyzed numerically. Good agree...

We consider an atomic beam reservoir as a source of quantum noise. The atoms are modelled as two-state systems and interact one-at-a-time with the system. The Floquet operators are described in terms of the Fermionic creation, annihilation and number operators associated with the two-state atom. In the limit where the time between interactions goes to zero and the interaction is suitably scaled...

We analyze a two-offspring Branching Annihilating Random Walk (n = 2 BAW) model, with finite annihilation rate. The finite annihilation rate allows for a dynamical phase transition between a vacuum, absorbing state and a non-empty, active steady state. We find numerically that this transition belongs to the same universality class as BAW’s with an even number of offspring, n ≥ 4, and that of ot...

The pair annihilation of straight line defects with strength +/-1/2 in bulk nematic systems is studied numerically, considering a full coupling of orientational degrees of freedom and hydrodynamics. This work is based on the generalization of the Ericksen-Leslie theory to the tensor order parameter as proposed by Qian and Sheng [T. Qian and P. Sheng, Phys. Rev. E 58, 7475 (1998)]. The approach ...