13242527
MASS EFFECTS IN THE QUARK–GLUON DECAYS OF HEAVY PARAQUARKONIA
Quark–gluon decays of heavy paraquarkonia are investigated with account of the masses of final quarks. The decay widths and the energy distributions of the final quarks and gluons are calculated in dependence on the relative quark masses. The strong collinear enhancement of the gluon energy distribution at the end of the spectrum is shown to take place in all such decays of ηc and ηb mesons except the decay . The total decay width is shown to have an essential dependence on the final quark masses. The corresponding branching ratios of ηc and ηb mesons are numerically estimated with a good agreement of with experimental data on ηc decays.
125367645
Field-induced axion luminosity of photon gas via a gamma gamma interaction
119416690
MASS SHIFT OF AXION IN MAGNETIC FIELD
A mass-shift of the axion propagating in an external constant homogenious magnetic field is calculated. The contributions via an electron loop and a virtual photon are examined. It is shown that the virtual photon contribution dominates substantially over the electron-loop one. Under the conditions of the early Universe the electron-loop contribution to the massless axion mass-shift is equal to zero while the virtual photon contribution is finite and can be of order of the recent restrictions on the axion mass.
118959729
Axion in an external electromagnetic field
We investigate the effective interaction of a pseudoscalar particle with two photons in an external electromagnetic field in the general case of all external particles being off the mass shell. This interaction is used to study the radiative decay $\stackrel{\ensuremath{\rightarrow}}{a}\ensuremath{\gamma}\ensuremath{\gamma}$ of the axion, a pseudoscalar particle associated with the Peccei-Quinn symmetry, and the crossing channel of photon splitting $\stackrel{\ensuremath{\rightarrow}}{\ensuremath{\gamma}}\ensuremath{\gamma}a$. It is shown that the external field removes the suppression associated with the smallness of the axion mass and so leads to the strong catalysis of these processes. The field-induced axion emission by the photon is analyzed as one more possible source of energy loss by astrophysical objects.