Related papers: Instantons in Lepton Pair Production
In this article, we have explored the very important quantity of lepton pair production from a hot and dense QCD medium in presence of an arbitrary external magnetic field for simultaneous nonzero values of both the parallel (along the…
The new approach to the lepton pair production in the Coulomb field of two highly relativistic nuclei was developed.Solving the operator equation for lepton scattering in arbitrary Coulomb field, we obtain the amplitudes for lepton…
The instanton vacuum picture is used to study hadronic matrix elements of the twist-3 (dimension-4, spin-1) QCD operators measuring the quark spin density and spin-orbit correlations. The QCD operators are converted to effective operators…
The breaking of the Lam-Tung relation in the Drell-Yan process at the LHC exhibits a long-standing tension with the Standard Model (SM) prediction at $\mathcal{O}(\alpha_s^3)$ accuracy. This tension could be explained by weak dipole…
The role of the QCD vacuum effects in high energy diffractive quark-quark and quark-antiquark scattering is studied with the Instanton Liquid Model. The special attention is given to the problem of formation of the soft Pomeron. We show…
Reformulating the instantons in a complex plane for tunneling or transmitting states, we calculate the pair-production rate of charged fermions in a spatially localized electric field, illustrated by the Sauter electric field E_0 sech^2…
The differential cross section for the dilepton production is calculated including Fermi motion of hadron constituents as well as emission from the ladders in the formalism of unintegrated parton distributions. We use unintegrated parton…
We show that lepton-pair production in Virtual Compton Scattering offers, through interference with the well-known Bethe-Heitler process, a sensitive probe to learn the longitudinal response of resonances and the electromagnetic nucleon…
We consider the production of a lepton-antilepton pair by real photons off a hadronic target. The interference of one and two photon exchange amplitudes leads to a charge asymmetry term that may be calculated explicitly in the large-t limit…
Electron-positron pair production is considered in the relativistic collision of a nucleus and an anti-nucleus, in which both leptons are created in bound states of the corresponding nucleus-lepton system. Compared to free and bound-free…
We investigate the $P_T$-broadening effects in dilepton production through photon-photon scattering in heavy ion collisions. The QED multiple interaction effects with the medium is found to be consistent with a recent observation of low…
We study the transverse momentum distribution for a $pair$ of heavy quarks produced in hadron-hadron interactions. Predictions for the large transverse momentum region are based on exact order $\alpha_s^3$ QCD perturbation theory. For the…
We discuss the angular distribution of the lepton pair in the Drell-Yan process, hadron+hadron -> \gamma^* X -> l^+ l^- X. This process gives information on the spin-density matrix \rho^{(q,\bar{q})} of the annihilating quark-antiquark pair…
We investigate the angular distribution of the lepton pair in the process $p \bar{p} \rightarrow \gamma^{\ast} + X \rightarrow \ell^+\ell^- + X$, where the virtual photon is produced at high transverse momentum. The angular distribution of…
Central production of lepton-lepton pairs ($e^+e^-$ and $\mu^+\mu^-$) and heavy quark composite states (charmonia and bottomonia) in diffractive proton collisions (proton momenta transferred ${|\bf q_\perp}|\sim m/\ln s$) are studied at…
Gluon two- and three-point Green Functions computed in Landau gauge from the lattice show the existence of power corrections to the purely perturbative expressions, that can be explained through an Operator Product Expansion as the…
Recently, significant enhancements of $e^{+} e^{-}$ pair production at very low transverse momentum ($p_{T} < 0.15$ GeV/c) were observed by the STAR collaboration in peripheral hadronic A+A collisions. This excesses can not be described by…
The production of jet pairs with small transverse momentum and large relative rapidity in high energy hadron-hadron collisions is studied. The rise of the parton-level cross section with increasing rapidity gap is a fundamental prediction…
Instanton effects on the Euclidean correlation function of two Wilson loops at an angle $\theta$, relevant to soft high-energy dipole-dipole scattering, are calculated in the Instanton Liquid Model and compared with the existing lattice…
We investigate several ingredients for a theory of multiple hard scattering in hadron-hadron collisions. Issues discussed include the space-time structure of multiple interactions, their power behavior, spin and color correlations,…