相关论文: Enhanced photon production rate on the light--cone
The process of large-angle high energy electron-positron scattering with emission of one hard photon almost collinear to one of the charged particles momenta is considered. The differential cross section with radiative corrections due to…
The present theoretical knowledge about photons and hard photoproduction processes, i.e. the production of jets, light and heavy hadrons, quarkonia, and prompt photons in photon-photon and photon-hadron collisions, is reviewed. Virtual and…
Exclusive diffractive photoproduction of heavy vector mesons (V=phi, J/psi and Upsilon) at HERA is studied in a model employing a dipole Pomeron exchange (P) with an inelastic gamma-P-V vertex. The model is fitted to the data on dsigma/dt,…
Effective photon-photon luminosities are calculated for various realistic hadron collider scenarios. The main characteristics of photon-photon processes at relativistic heavy-ion colliders are established and compared to the corresponding…
Effective photon-photon luminosities are calculated for various realistic hadron collider scenarios. The main characteristics of photon-photon processes at relativistic heavy-ion colliders are established and compared to the corresponding…
This talk reviews the status of QCD calculations of photon and dilepton production rates in a Quark-Gluon plasma. Theses rates are known to order ${\cal O}(\alpha_s)$. Their calculations involve various resummations to account for well…
The exclusive reaction $\gamma p \to p \pi^+ \pi^-$ was studied in the photon energy range 3.0 - 3.8 GeV and momentum transfer range $0.4<-t<1.0$ GeV$^2$. Data were collected with the CLAS detector at the Thomas Jefferson National…
A consistent factorization theorem is presented in the framework of effective field theories. Conventional factorization suffers from infrared divergences in the soft and collinear parts. We present a factorization theorem in which the…
We reanalyze the WA98 single photon data at CERN SPS by incorporating several recent developments in the study of prompt and thermal photon production from relativistic heavy ion collisions. Isospin and shadowing corrected NLO pQCD, along…
Current light-cone wave functions for the nucleon are unsatisfactory since they are in conflict with the data of the nucleon's Dirac form factor at large momentum transfer. Therefore, we attempt a determination of a new wave function…
We re-examine observables with rapidity divergences in the context of a formulation of Soft-Collinear Effective Theory in which infrared degrees of freedom are not explicitly separated into modes. We consider the Sudakov form factor with a…
We present a parametric estimate of photon production at early times in heavy-ion collisions based on a consistent weak coupling thermalization scenario. We quantify the contribution of the off-equilibrium Glasma phase relative to that of a…
We give a brief account of recent theoretical developments in prompt photon production.
In this article, we investigate the contribution of the higher-twist Feynman diagrams to the large-$p_T$ inclusive single meson production cross section in photon-photon collisions and present the general formulas for the higher-twist…
Dark photons, a generic class of light gauge bosons that interact with the Standard Model (SM) exclusively through kinetic mixing, arise naturally in many gauge extensions of the SM. Motivated by these theoretical considerations, we present…
We investigate threshold pion photoproduction in the framework of heavy baryon chiral perturbation theory. We give the expansion of the electric dipole amplitude $E_{0+}$ to three orders in $\mu$, the ratio of the pion to nucleon mass, and…
In this work we propose a new mechanism for photoproduction inside a neutron star based on Parametric Resonance phenomenon as firstly applied to Inflationary Cosmology. Our assumptions are based on the pion condensation model by Harrington…
We compute the production rate of lepton pair by static photons at finite temperature at two-loop order. We treat the infrared region of the gluon phase space carefully by using a hard thermal loop gluon propagator. The result is free of…
Helicity amplitudes and differential cross section of high-energy $e^+e^-$ photoproduction accompanied by bremsstrahlung in the electric field of a heavy atom are derived. The results are exact in the nuclear charge number and obtained in…
Positron beams, both polarized and non-polarized, low and high energy have a wide range of applications and many methods can be used to produce them. In this paper we analyse the two main methods used to produce positrons for accelerator…