相关论文: The Pair Production Spectrum from Photon-Photon An…
Process of lepton pair production by polarized photon on nuclei can be used to measure the degree of linear polarization of high energy photon. The differential cross section and the analyzing power are calculated with taking into account…
We report a measurement of the differential cross section of $\pi^0$ pair production in single-tag two-photon collisions, $\gamma^* \gamma \to \pi^0 \pi^0$, in $e^+ e^-$ scattering. The cross section is measured for $Q^2$ up to 30 GeV$^2$,…
The production of photon pairs in $e^+e^-\rightarrow f \bar f \gamma\gamma$ processes is studied using exact helicity amplitudes at tree level. Total cross sections, including initial state radiation effects, are given. They are presented…
The total cross section for Coulomb photoproduction of neutral pion pairs in the reaction gamma A --> pi0 pi0 A is estimated within the effective chiral lagrangian approach. The amplitude of gamma gamma* --> pi0 pi0 with one off-shell…
This work extends our previous studies of two-photon annihilation into baryon-antibaryon pairs from spin-1/2 octet to spin-3/2 decuplet baryons. Our approach is based on perturbative QCD and treats baryons as quark-diquark systems. Using…
The new approach is developed for study of electron-positron pair production by a photon in oriented single crystal. It permits indivisible consideration of both coherent and incoherent mechanisms of pair creation and includes the action of…
We describe the process $\gamma N \to \gamma\,\rho N'$ in the generalized Bjorken regime where the $\gamma\,\rho $ pair has a large invariant mass. In the collinear QCD factorization framework, the amplitude gives access to both chiral-even…
We consider the electron-positron pair creation by a photon in an external constant electric field. The presented treatment is based on a purely quasiclassical calculation of the imaginary part of the on-shell photon polarization operator.…
We discuss the pair production of charginos in collisions of polarized photons $\gamma\gamma \to \tilde{\chi}_i^+ \tilde{\chi}_i^-$, ($i=1,2$) and the subsequent leptonic decay of the lighter chargino $\tilde{\chi}_1^+ \to \tilde{\chi}_1^0…
With a special choice of gauge the operator of the Klein-Fock-Gordon equation in homogeneous electric field respects boost symmetry. Using this symmetry we obtain solutions for the scalar massive field equation in such a background (boost…
A detailed analysis of electron-positron pair creation induced by a spatially nonuniform and static electric field from vacuum is presented. A typical example is provided by the Sauter potential. For this potential, we derive the analytic…
We present some comments on Schwinger's calculation of electron-positron production in a prescribed constant electric field. The range of validity of 2 Im \mathcal{L}^(1)(E) is discussed thoroughly and limiting cases are provided.
We consider the electron-positron pair production by a photon in Coulomb field near threshold. We obtain the analytical results for the particle energy spectrum and angular distribution exactly in the parameter $Ze^2/\hbar v$. We show that…
We report on the realization of a liquid-filled optical microcavity and demonstrate photon-pair generation by spontaneous four-wave mixing. The bandwidth of the emitted photons is $\sim 300$ MHz and we demonstrate tuning of the emission…
Prolific electron-positron pair production is possible at laser intensities approaching 10^{24} W/cm^2 at a wavelength of 1 micron. An analysis of electron trajectories and interactions at the nodes (B=0) of two counter-propagating,…
We calculate total and differential production rates of D* mesons in two-photon collisions at LEP2. We include full next-to-leading order QCD corrections, and perform an extensive study of the sensitivity of our predictions to variations of…
We compute the photon emission rate of an equilibrated, hot QCD plasma at zero chemical potential, to leading order in both alpha_{EM} and the QCD coupling g_s(T). This requires inclusion of near-collinear bremsstrahlung and inelastic pair…
Coherent pion photoproduction, $d(\gamma,\pi^0)d$, is calculated in a coupled channels approach in momentum space using an elementary production operator that includes Born terms, vector meson exchange and $M1/E2$ $\Delta$-resonance…
A new channel of direct photon production from a quark gluon plasma (QGP) is explored. This process appears at Next-to-Leading-Order in the presence of a charge asymmetry in the heated matter and may be effectively described as the…
We study electron-positron pair production within two counter-propagating, circularly polarized electromagnetic fields through the Wigner formalism. We numerically generate high-resolution momentum maps to perform a detailed spectroscopic…