Related papers: Photon emission from weakly magnetized neutral pio…
We derive novel low--energy theorems for single pion production off nucleons through the isovector axial current. We find that the $k^2$-dependence of the multipole $L_{0+}^{(+)}$ at threshold is given by the nucleon scalar form factor,…
Threshold neutral pion photoproduction on light nuclei is studied in the framework of baryon chiral perturbation theory. We obtain a general formula for the electric dipole amplitude in the special case of neutral pion photoproduction on a…
We calculate the decay of pionium atoms into two photons. The pion polarizability gives rise to a 10% correction to the corresponding decay width for pointlike pions. This opens the possibility to obtain the difference between the electric…
We investigate the production of photons from coherently oscillating, spatially localized clumps of axionic fields (oscillons and axion stars) in the presence of external electromagnetic fields. We delineate different qualitative behaviour…
Previous results from the authors concerning the arising a tiny photon anomalous paramagnetic moment $\mu_{\gamma}$ due to its interaction with a magnetized virtual electron-positron background are complemented and discussed. It is argued…
We study production of photons via the non-equilibrium relaxation of a Disoriented Chiral Condensate with the chiral order parameter having a large initial amplitude along the \pi^0 direction. Assuming the validity of the low energy…
Methods are set forth for determining the hadron electromagnetic structure in the sub-$N\bar{N}$-threshold timelike region of the virtual-photon ``mass'' and for investigating the nucleon weak structure in the spacelike region from…
Light, beyond-the-standard-model particles $X$ in the 1-100 MeV mass range can be produced in nuclear and hadronic reactions but would have to decay electromagnetically. We show that simple and well-understood low-energy hadronic processes…
The differential cross sections and unpolarized spin-density matrix elements for the reaction $\gamma p\to p\omega$ were measured using the CBELSA/TAPS experiment for initial photon energies ranging from the reaction threshold to 2.5 GeV.…
We consider the coupling of the electromagnetic vacuum field with an oscillating perfectly-reflecting mirror in the nonrelativistic approximation. As a consequence of the frequency modulation associated to the motion of the mirror, low…
We compute the neutral pion mass dependence on a magnetic field in the weak field approximation at one-loop order. The calculation is carried out within the linear sigma model coupled to quarks and using Schwinger's proper-time…
The $\gamma n \to \pi^0 n$ differential cross section evaluated for 27 energy bins span the photon-energy range 290-813 MeV (W = 1.195-1.553 GeV) and the pion c.m. polar production angles, ranging from 18 deg to 162 deg, making use of…
Precise total cross-sections and invariant-mass distributions have been measured for photoproduction of pion pairs off the proton producing $p\pi^0\pi^0$ and $n\pi^+\pi^0$ final states from the threshold region up to 800 MeV incident photon…
This paper reports on results from an experiment designed to search for exotic particles interacting with nuclear matter. These particles could be created through the Primakoff coupling between photons and an external magnetic field. Theory…
We derive relative upper bounds on the effective magnetic moment of Dirac neutrinos from comparison of the standard weak and electromagnetic mechanisms of the neutrino luminosity due to the Compton-like photoproduction of neutrino pairs in…
Recent results for the photoproduction of mesons off nuclei are reviewed. These experiments have been performed for two major lines of research related to the properties of the strong interaction. The investigation of nucleon resonances…
We present the first detailed measurement of incoherent photoproduction of neutral pions to a discrete state of a residual nucleus. The $^{12}$C$(\gamma,\pi^{0})^{12}$C$^{*}_{4.4MeV}$ reaction has been studied with the Glasgow photon tagger…
We develop a formalism for the photon emission from the quark-gluon plasma with an external electromagnetic field. We then use it to investigate the effect of magnetic field on the photon emission from the quark-gluon plasma created in $AA$…
We study di-lepton production from a single photon in the presence of a strong constant magnetic field. By the use of the Ritus-basis formalism, we analytically evaluate the photon--to--di-lepton conversion vertex with fully taking into…
Using magnetic white dwarfs as a case study, we show that the emission of sub-MeV bosons from stellar plasmas can be substantially modified in the presence of a magnetic field. In particular, the magnetic field-induced anisotropy and…