Related papers: Higher Twist Effects in Photon-Photon Collisions
We study the posibility of large isospin fluctuations in high-energy heavy-ion collisions by assuming that pions are produced semiclassically both directly and in pairs through the isovector channel. The leading-particle effect and the…
We compute the pion inclusive momentum distribution in heavy-ion collisions at AGS energies, assuming thermal equilibrium and accounting for density and expansion effects at the time of decoupling. We compare to data on mid rapidity charged…
We calculate the centrality dependence of direct photons produced in Au+Au collisions at sqrt{s}=200GeV and their transverse momentum spectra within the Parton-Hadron-String Dynamics (PHSD) transport approach. As sources for 'direct'…
The pion electromagnetic form factor is calculated within the QCD light-cone sum rule method and using a renormalon model for the higher twist distribution amplitudes (DAs). The theoretical predictions are compared with the experimental…
The methods allowing to extract the coherent component of pion emission conditioned by the formation of a quasi-classical pion source in heavy ion collisions are suggested. They exploit a nontrivial modification of the quantum statistical…
We reanalyze the $\gamma\gamma^{*} \to \pi^{0}$ transition form factor $F_{\pi\gamma}(Q^2)$ within the QCD light-cone sum rules method with the twist-4 accuracy. In computations the pion leading twist distribution amplitude (DA) with two…
Transverse momentum spectra of negative and positive pions produced at mid-(pseudo)rapidity in inelastic or non-single-diffractive proton-proton collisions over a center-of-mass energy, $\sqrt{s}$, range from a few GeV to above 10 TeV are…
Within the collinear twist-3 framework, we analyze the double-spin asymmetry in collisions between longitudinally polarized nucleons and transversely polarized nucleons with focus on hadron and jet production. As was the case in direct…
Within the framework of a thermal model with its parameters fitted to the results from an isospin-dependent Boltzmann-Uehling-Uhlenbeck (IBUU) transport model, we study the pion in-medium effect on the charged-pion ratio in heavy-ion…
We study the electromagnetic and meson-photon transition form factors (TFF) of light pseudoscalar mesons from the perturbative QCD (pQCD) approach. To comprehensively account for both the longitudinal and transverse nonperturbative dynamics…
We calculate the "naive non-abelianization" (NNA) contributions of the higher-twist Feynman diagrams to the large-$p_T$ inclusive pion production cross section in proton-proton collisions in the case of the running coupling and frozen…
Meson--photon--photon transition form factors for S-, P-, and D-wave states are calculated, the meson being treated as a non-relativistic heavy-quark--antiquark pair. The full dependence on both photon virtualities is included.…
The cross sections for the production of two-pions in ultraperipheral ultrarelativistic heavy ion collisions, calculated in the impact parameter Equivalent Photon Approximation (EPA), are presented. Differential distributions in impact…
We calculate the QCD moments of the pion structure function using Drell-Yan data on the quark distributions in the pion and a phenomenological model for the resonance region. The extracted higher twist corrections are found to be larger…
The invariant differential cross sections for inclusive $\pi^{0}$ and $\eta$ mesons at midrapidity were measured in pp collisions at $\sqrt{s}=2.76$ TeV for transverse momenta $0.4<p_{\rm T}<40$ GeV/$c$ and $0.6<p_{\rm T}<20$ GeV/$c$,…
Dilepton spectra from the decay of phi mesons produced in heavy-ion collisions at SIS/GSI energies ($\sim 2$ GeV/nucleon) are studied in the relativistic transport model. We include phi mesons produced from baryon-baryon, pion-baryon, and…
The electromagnetic pion production reactions are investigated within the dynamical coupled-channels model developed in {\bf Physics Reports, 439, 193 (2007)}. The meson-baryon channels included in this study are $\gamma N$, $\pi N$, $\eta…
We discuss the photon to meson transition form factor for virtual photons, which can be measured in e+ e- collisions. We demonstrate that this form factor is independent of the shape of the meson distribution amplitude over a wide…
We calculate the cross section and transverse-momentum ($P_{\bot}$) distribution of the Breit-Wheeler process in relativistic heavy-ion collisions and their dependence on collision impact parameter ($b$). To accomplish this, the Equivalent…
We recently presented a method of analyzing invariant-mass spectra of kaon pairs resulting from decay of $\phi$ mesons produced in high-energy heavy-ion collisions. It can be used to extract the shifts in the mass and the width ($\Delta M$…