The expansion of operators as ordered power series in the annihilation and creation operators a and a~ is examined. It is found that normally ordered power series exist and converge quite generally, but that for the case of antinormal ordering the required c-number coefficients are infinite for important classes of operators. A parametric ordering convention is introduced according to which nor...

Graph games with an annihilation rule, as introduced by Conway, Fraenkel and Yesha, are studied under the midre play rule for progressively finite graphs that satisfy a condition on the reversibility of non-terminal Sprague-Grundy zeros to Spragu+Grundy ones. Two general theorems on the Spragu+Grundy zeros and ones are given, followed by two theorems characterizing the set of P-positions under ...

A unified picture of nucleon antinucleon annihilation into pions emerges from a classical description of the pion wave produced in annihilation and the subsequent quantization of that wave as a coherent state. When the constraints of energy-momentum and iso-spin conservation are imposed on the coherent state, the pion number distribution and charge ratios are found to be in excellent agreement ...

• A meson creation operator is a suitable linear combination of building blocks (1), yielding well defined quantum numbers with respect to total angular momentum J , parity P and, in the case of identical quark flavors, charge conjugation C (the “spatial structure of the meson” U [angular momentum L, (angular momentum) parity P and (angular momentum) charge conjugation C) and its spin part Γ ha...

We compare results of four public supersymmetric (SUSY) spectrum codes, ISAJET7.71, SOFTSUSY1.9, SPHENO2.2.2 and SUSPECT2.3 to estimate the presentday uncertainty in the calculation of the relic density of dark matter in mSUGRA models. We find that even for mass differences of about 1% the spread in the obtained relic densities can be 10%. In difficult regions of the parameter space, such as la...

A proof is given that an invertible and a unitary operator can be used to reproduce the effect of a q-deformed commutator of annihilation and creation operators. In other words, the original annihilation and creation operators are mapped into new operators, not conjugate to each other, whose standard commutator equals the identity plus a correction proportional to the original number operator. ...

An exploration of dislocation microstructure evolution with different misorientation angles was performed using phase field crystal method (PFC). The microcosmic process grain boundaries under external stress, as well the corresponding energy curve and stress–strain curve, are analyzed. relationship between angle dislocations emission frequency is discussed. Three forms reaction on 6° 10° analy...

The aim of this work is to identify the mechanisms responsible for very large rates and other peculiarities observed in low-energy positron annihilation on molecules. The two mechanisms considered are: (i) Direct annihilation of the incoming positron with one of the molecular electrons. This mechanism dominates for atoms and small molecules. I show that its contribution to the annihilation rate...

By solving the Fokker-Planck equation directly we examine the effects of annihilation, particle escape and injection on the form of a steady-state positron distribution in thermal hydrogen plasmas with kT < mec. The positron fraction considered is small enough, so it does not affect the electron distribution which remains Maxwellian. We show that the escape of positrons in the form of electron-...