Related papers: Pionic transparency in semi-exclusive electroprodu…
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…
A process of Central Exclusive $\pi^+\pi^-$ production in proton-proton collisions and its theoretical description is presented. A possibility of its measurement, during the special low luminosity LHC runs, with the help of the ATLAS…
Ongoing experiments at JLAB investigate the nuclear transparency in exclusive rho0(770) electroproduction off nuclei. In this work we present transport model predictions for the attenuation of rho0s in nuclei and for color transparency (CT)…
We investigate hard exclusive reactions on the nucleon with soft pion emission. A parametrization of corresponding hadronic matrix elements in terms of parton distributions for final pion-nucleon state is provided. These distributions are…
We present a new calculation of axion-like particle (ALP) production in the semi-exclusive photon-initiated (PI) channel, that is either with intact outgoing protons or rapidity gaps present in the final state, and with no colour flow…
A review of our works providing a theoretical description of incoherent pion photoproduction on the deuteron is presented. The existing $\gamma d\to\pi NN$ data are analysed, especially those obtained more recently by the CLAS Collaboration…
Measurements of the double-differential $\pi^{\pm}$ production cross-section in the range of momentum $0.5 \GeVc \leq p \le 8.0 \GeVc$ and angle $0.025 \rad \leq \theta \le 0.25 \rad$ in interactions of charged pions on beryllium, carbon,…
A significant excess of J/$\psi$ yield at very low transverse momentum ($p_T < 0.3$ GeV/c) was observed by the ALICE and STAR collaborations in peripheral A+A collisions, which points to evidence of coherent photoproduction of J/$\psi$ in…
We calculate quasi-exclusive scattering of a virtual photon and a proton or pion in nuclear targets. This is the first complete calculation of ``color transparency" and "nuclear filtering " in perturbative QCD. The calculation includes full…
The $\eta N$ final state is isospin-selective and thus provides access to the spectrum of excited nucleons without being affected by excited $\Delta$ states. To this end, the world database on eta photoproduction off the proton up to a…
We report the first experimental measurements of the nine 1-fold differential cross sections for the $\gamma p \to \pi^+\pi^-p$ reaction, obtained with the CLAS detector at Jefferson Laboratory. The measurements cover the invariant mass…
The electric ${\alpha}_{\pi}$ and magnetic $\beta_{\pi}$ charged pion Compton polarizabilities are of fundamental interest in the low-energy sector of quantum chromodynamics (QCD).They are directly linked to the phenomenon of spontaneously…
As one of the predictions of perturbative QCD, the effect of color transparency has been the focus of attention in the community studying modifications of hadrons in nuclear medium for several decades. The search for this effect in…
Photoproduction of $\pi^{0}\pi^{0}$ and $\pi^{0}\pi^{\pm}$ pairs from nuclei has been measured over a wide mass range ($^2$H, $^{7}$Li, $^{12}$C, $^{40}$Ca, and $^{\rm nat}$Pb) for photon energies from threshold to 600 MeV. The experiments…
Background: Energetic quarks in nuclear DIS propagate through the nuclear medium. Processes that are believed to occur inside nuclei include quark energy loss through medium-stimulated gluon bremsstrahlung and intra-nuclear interactions of…
We use QCD to compute the cross section for coherent production of a di-jet (treated as a $q\bar q$ moving at high relative transverse momentum,$\kappa_t $). In the target rest frame,the space-time evolution of this reaction is dominated by…
QCD-based scaling arguments predict the predominance of longitudinal over transverse electroproduction of pions by terms $\propto Q^2$. However, data from JLAB, Cornell and DESY, covering a wide kinematical range $1 < Q^2 < 11\, {\rm…
The charged and neutral pion photoproduction reactions are investigated in a dynamical coupled-channels approach based on the formulation of Haberzettl, Huang, and Nakayama [Phys. Rev. C 83, 065502 (2011)]. The hadronic final-state…
We study the hard exclusive production of two pions in the virtual photon fragmentation region with various invariant masses including the resonance region. The amplitude is expressed in terms of two-pion light cone distribution amplitudes…
In the present paper we investigate pi0 pi0 and pi(+/-)pi0 photoproduction off complex nuclei at incident beam energies of 400-460 MeV. Simulations of two pion photoproduction on protons and nuclei are performed by means of a semi-classical…