Related papers: How pi0 -> gamma gamma changes with temperature
It is shown that the dependence of negative thermal expansion coefficient of many substances on the temperature contradicts to an important thermodynamic relation. It is supposed that there are oscillations at the Cp(T) and alpha(T) curves…
We study the rho^0 and phi decays into pi^+ pi^- gamma, pi^0 pi^0 gamma and phi into pi^0 eta gamma using a chiral unitary approach to deal with the final state interaction of the M M system. The final state interaction modifies only…
We investigate the gravitational anomaly vertex $\langle TTJ_5\rangle$ (graviton - graviton - axial current) under conditions of finite density and temperature. Through a direct analysis of perturbative contributions, we demonstrate that…
The two photon decay width of the neutral pion is analyzed within the combined framework of Chiral Perturbation Theory and the 1/Nc expansion up to order p^6 and p^4 times 1/Nc in the decay amplitude. The eta' is explicitly included in the…
We present a new contribution to the $K_L\rightarrow \gamma \gamma$ amplitude, which is ${\cal{O}}(p^4)$ within the counting rules of chiral perturbation theory. This direct (non-pole) amplitude, obtained from short-distance $s \rightarrow…
The decay modes $\rho^0 \to 2\pi^+ 2\pi^-$ and $\rho^0 \to 2\pi^0 \pi^+ \pi^-$ are considered in the framework of the low energy effective chiral Lagrangian. The obtained values of the decay widths $\Gamma(\rho^0\to 2 \pi^+ 2 \pi^-)=$ $(16…
We study again the phenomenon of charge fractionalization at finite temperature. Our calculations are done in a framework in which the connection between the induced fermion number and the chiral anomaly is manifest. We find that the…
The conservation of the vector current and the axial anomaly responsible for the $\pi_0 \to \gamma \gamma$ decay amplitude are obtained in leading order within the Taylor-Lagrange formulation of fields considered as operator-valued…
The problem of $\gamma \pi \to \pi \pi$ is studied using the axial anomaly, elastic unitarity, analyticity and crossing symmetry. The solution of the integral equation for this amplitude is given by an iteration procedure.The final solution…
We present a complete analysis of K -> 3 pi gamma decays to O(p^4) in the low-energy expansion of the Standard Model. We employ the notion of "generalized bremsstrahlung" to take full advantage of experimental information on the…
We show that the evolution of magnetic fields in a primordial plasma, filled with Standard Model particles, at temperatures T > 10 MeV is strongly affected by the quantum chiral anomaly -- an effect that has been neglected previously.…
Measurement of the $\gamma 3\pi$ process has revealed a possible conflict with what should be a solid prediction generated by the chiral anomaly. We show that inclusion of appropirate energy-momentum dependence in the matrix element reduces…
We show that the vacuum (zero-point) energy of a low-temperature quantum liquid is a variable property which changes with the state of the system, in notable contrast to the static vacuum energy in solids commonly considered. We further…
1. Introduction: a) motivations, b) status, c) purpose, d) results 2. Kinematics and couplings 3. Decay amplitude (analytic expression): a) tree level, b) one loop 4. Decay width (numerical): a) diphoton energy spectrum [energy cut] 5.…
Radiative corrections to the decay rate of charged fermions caused by the presence of a thermal bath of photons are calculated in the limit when temperatures are below the masses of all charged particles involved. The cancellation of…
A model is described that relates the temperature coefficient of the optical absorption spectrum of pure water to the frequency derivative of that spectrum and two parameters that quantify the dependence of a peak's amplitude and its…
Two closely related topological phenomena are studied at finite density and temperature. These are chiral anomaly and Chern--Simons term. It occurs that the chiral anomaly doesn't depend on density and temperature. Chern-Simons term…
This study shows that the charge disproportionation at the Bi site in BaBiO$_3$ alters as a function of temperature. Decreasing the temperature from 300K down to 160K leads to a significant modification of the density of states…
The form factor for the anomalous process gamma pi^+ -> pi^+ pi^0, which is presently being measured at CEBAF, is calculated in the Schwinger-Dyson approach in conjunction with an impulse approximation. The form factors obtained by us are…
The $\gamma^* \pi^0 \rightarrow \gamma$ form factor, including the extension off the pion mass-shell, is obtained from a generalized impulse approximation within a QCD-based model field theory known to provide an excellent description of…